Podcast
Questions and Answers
Which classes of vertebrates are generally considered fish?
Which classes of vertebrates are generally considered fish?
What percentage of known fish species are found in marine environments?
What percentage of known fish species are found in marine environments?
What is the smallest unit in the hierarchical classification of organisms?
What is the smallest unit in the hierarchical classification of organisms?
Which environment hosts the highest number of fish species according to the document?
Which environment hosts the highest number of fish species according to the document?
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In binominal nomenclature, how is the genus name presented?
In binominal nomenclature, how is the genus name presented?
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How many species are estimated to inhabit the cold polar waters?
How many species are estimated to inhabit the cold polar waters?
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Which of the following is true regarding fish species distribution?
Which of the following is true regarding fish species distribution?
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What is the proper classification hierarchy from species to kingdom?
What is the proper classification hierarchy from species to kingdom?
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What is the primary reason scientific names should be used in publications?
What is the primary reason scientific names should be used in publications?
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Which group of fish is classified as having a high urea content in muscle?
Which group of fish is classified as having a high urea content in muscle?
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What distinguishes demersal fish from pelagic fish?
What distinguishes demersal fish from pelagic fish?
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How do fish muscle cells differ from those of terrestrial mammals?
How do fish muscle cells differ from those of terrestrial mammals?
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What is the role of the myocommata in fish anatomy?
What is the role of the myocommata in fish anatomy?
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Which factor causes dark muscle to be more prevalent in pelagic fish?
Which factor causes dark muscle to be more prevalent in pelagic fish?
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What type of muscle tissue is predominant in most fish?
What type of muscle tissue is predominant in most fish?
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Why is the presence of lipids significant in the muscle tissue of fish?
Why is the presence of lipids significant in the muscle tissue of fish?
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Which pigment is responsible for the reddish color in salmon and sea trout?
Which pigment is responsible for the reddish color in salmon and sea trout?
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Which classification group contains jawless fish?
Which classification group contains jawless fish?
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What anatomical feature runs the full length between two myocommata in fish?
What anatomical feature runs the full length between two myocommata in fish?
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What is the distinctive characteristic of bony fish muscles compared to cartilaginous fish muscles?
What is the distinctive characteristic of bony fish muscles compared to cartilaginous fish muscles?
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Which statement about false ribs in fish is true?
Which statement about false ribs in fish is true?
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Where do the longest muscle cells in cod typically occur?
Where do the longest muscle cells in cod typically occur?
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What is the recommended bleeding period for fish before they are gutted?
What is the recommended bleeding period for fish before they are gutted?
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What complication arises from the two-step procedure of bleeding followed by gutting?
What complication arises from the two-step procedure of bleeding followed by gutting?
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Which factor is most critical for achieving the best bleeding results in fish?
Which factor is most critical for achieving the best bleeding results in fish?
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What did Huss and Asenjo find about the cutting method for optimal bleeding?
What did Huss and Asenjo find about the cutting method for optimal bleeding?
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Which organs in fish are recognized as major foodstuffs?
Which organs in fish are recognized as major foodstuffs?
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What changes occur in cod muscle prior to spawning?
What changes occur in cod muscle prior to spawning?
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At what stage do most fish become sexually mature?
At what stage do most fish become sexually mature?
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Which fish species is known to only migrate once before degenerating and dying?
Which fish species is known to only migrate once before degenerating and dying?
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What happens to the lipid content during migration in Pacific salmon?
What happens to the lipid content during migration in Pacific salmon?
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How does the growth process affect muscle cells in fish?
How does the growth process affect muscle cells in fish?
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Which of the following statements relates to the weight of a fish prior to spawning?
Which of the following statements relates to the weight of a fish prior to spawning?
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What is a secondary effect of rough handling of fish during capture?
What is a secondary effect of rough handling of fish during capture?
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What occurs to fish reserves during gonadal development?
What occurs to fish reserves during gonadal development?
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What is the lifespan of North Sea cod in relation to spawning?
What is the lifespan of North Sea cod in relation to spawning?
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What is one key attribute of the fish heart's design?
What is one key attribute of the fish heart's design?
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What is the primary reason for including astaxanthin in fish feed during aquaculture?
What is the primary reason for including astaxanthin in fish feed during aquaculture?
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What is the role of Ca++ in muscle contraction according to physiological processes described?
What is the role of Ca++ in muscle contraction according to physiological processes described?
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Why do salmonids living in waters with little carotenoid exhibit less red muscle color?
Why do salmonids living in waters with little carotenoid exhibit less red muscle color?
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What is a major difference between light muscle and dark muscle in fish?
What is a major difference between light muscle and dark muscle in fish?
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What happens to muscle fibers when ATP levels reach a minimum post-mortem?
What happens to muscle fibers when ATP levels reach a minimum post-mortem?
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How does the cardiovascular system of fish differ from that of mammals?
How does the cardiovascular system of fish differ from that of mammals?
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What occurs during blood circulation in a fish after blood passes through the gills?
What occurs during blood circulation in a fish after blood passes through the gills?
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How does the blood volume distribution in fish relate to muscle tissue?
How does the blood volume distribution in fish relate to muscle tissue?
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What physiological function primarily prevents counterflow of blood in fish veins?
What physiological function primarily prevents counterflow of blood in fish veins?
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What is the consequence of inadequate carotenoid ingestion in fish from low-carotenoid waters?
What is the consequence of inadequate carotenoid ingestion in fish from low-carotenoid waters?
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Why is muscle contraction important for blood circulation in fish?
Why is muscle contraction important for blood circulation in fish?
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What happens to lactic acid produced in light muscle during anaerobic metabolism?
What happens to lactic acid produced in light muscle during anaerobic metabolism?
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What physiological change occurs in fish muscle at spawning time?
What physiological change occurs in fish muscle at spawning time?
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What is the effect of post-mortem conditions on the ATP levels in fish muscle?
What is the effect of post-mortem conditions on the ATP levels in fish muscle?
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What occurs to fish muscle immediately after death?
What occurs to fish muscle immediately after death?
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How does high temperature affect rigor mortis in cod?
How does high temperature affect rigor mortis in cod?
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Which factor does NOT affect the rate of onset and resolution of rigor mortis in fish?
Which factor does NOT affect the rate of onset and resolution of rigor mortis in fish?
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What is the typical duration of rigor mortis after it begins?
What is the typical duration of rigor mortis after it begins?
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What phenomenon may occur due to strong rigor tensions in fish?
What phenomenon may occur due to strong rigor tensions in fish?
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What effect does cooler storage temperature have on the onset of rigor mortis in some tropical fish species?
What effect does cooler storage temperature have on the onset of rigor mortis in some tropical fish species?
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Which of the following statements is true regarding sensory changes in fish during storage?
Which of the following statements is true regarding sensory changes in fish during storage?
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Why is it generally accepted that the onset and duration of rigor mortis occur more rapidly at higher temperatures?
Why is it generally accepted that the onset and duration of rigor mortis occur more rapidly at higher temperatures?
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What is the primary factor that differentiates firm and elastic flesh from soft flesh in fish?
What is the primary factor that differentiates firm and elastic flesh from soft flesh in fish?
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What happens to the pH of cod muscle post-mortem as anaerobic glycolysis occurs?
What happens to the pH of cod muscle post-mortem as anaerobic glycolysis occurs?
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What visual characteristics indicate a fresh fish's eyes?
What visual characteristics indicate a fresh fish's eyes?
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How do enzymatic changes in fish affect freshness compared to bacterial spoilage?
How do enzymatic changes in fish affect freshness compared to bacterial spoilage?
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What is indicated by a yellowish color in the gills of fish?
What is indicated by a yellowish color in the gills of fish?
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In what condition is the flesh of fish described as velvety or waxy?
In what condition is the flesh of fish described as velvety or waxy?
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What is the consequence of oxygen deprivation in fish muscle immediately post-mortem?
What is the consequence of oxygen deprivation in fish muscle immediately post-mortem?
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What does a score lower than 4 signify on the sensory evaluation scale for fish?
What does a score lower than 4 signify on the sensory evaluation scale for fish?
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What type of respiration is primarily responsible for ATP production after a fish dies?
What type of respiration is primarily responsible for ATP production after a fish dies?
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What indicates that the kidneys and organ residues in fish have started to spoil?
What indicates that the kidneys and organ residues in fish have started to spoil?
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Which sensory characteristic should be present in the gills of fresh fish?
Which sensory characteristic should be present in the gills of fresh fish?
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Which of the following best describes the flesh condition when it sticks to the peritoneum?
Which of the following best describes the flesh condition when it sticks to the peritoneum?
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What end-products are generated from anaerobic metabolism during fish post-mortem?
What end-products are generated from anaerobic metabolism during fish post-mortem?
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Which factor strongly influences the degradation rate of chilled fish compared to ambient conditions?
Which factor strongly influences the degradation rate of chilled fish compared to ambient conditions?
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What is the effect of stunning and killing fish by hypothermia on the onset of rigor mortis?
What is the effect of stunning and killing fish by hypothermia on the onset of rigor mortis?
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What occurs to muscle fibers after ATP levels fall post-mortem?
What occurs to muscle fibers after ATP levels fall post-mortem?
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How does the texture of fish change when cooked post-rigor compared to pre-rigor?
How does the texture of fish change when cooked post-rigor compared to pre-rigor?
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What is the expected change in length of dark muscle when cooked pre-rigor?
What is the expected change in length of dark muscle when cooked pre-rigor?
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Which phase characterizes the very fresh fish with a sweet taste after catching?
Which phase characterizes the very fresh fish with a sweet taste after catching?
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What impact does rough handling of fish during capture have on fileting yield?
What impact does rough handling of fish during capture have on fileting yield?
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How does the state of glycogen reserves affect the onset of rigor mortis in fish?
How does the state of glycogen reserves affect the onset of rigor mortis in fish?
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Which of the following factors primarily affects the sensory evaluation of raw fish?
Which of the following factors primarily affects the sensory evaluation of raw fish?
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What happens to fish fillets if they are frozen pre-rigor and then thawed at low temperatures?
What happens to fish fillets if they are frozen pre-rigor and then thawed at low temperatures?
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What occurs during Phase 3 of fish spoilage?
What occurs during Phase 3 of fish spoilage?
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Which species demonstrates the shortest time from death to onset of rigor when stressed?
Which species demonstrates the shortest time from death to onset of rigor when stressed?
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What is a characteristic change in fish that is very fresh when compared to stored fish?
What is a characteristic change in fish that is very fresh when compared to stored fish?
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What does the term 'post-rigor' refer to in the quality of fish?
What does the term 'post-rigor' refer to in the quality of fish?
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When evaluating cooked fish, which phase indicates the first signs of spoilage?
When evaluating cooked fish, which phase indicates the first signs of spoilage?
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What is the typical pH range observed for large mackerel during rigor mortis?
What is the typical pH range observed for large mackerel during rigor mortis?
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How does stored glycogen in fish generally compare to that in mammals?
How does stored glycogen in fish generally compare to that in mammals?
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What effect does pre-capture stress have on the pH levels of fish muscle?
What effect does pre-capture stress have on the pH levels of fish muscle?
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What is indicated by a high 'K' value in the context of fish freshness?
What is indicated by a high 'K' value in the context of fish freshness?
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What is the role of ATP in muscle contraction?
What is the role of ATP in muscle contraction?
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Why are fish in rigor mortis unsuitable for processing?
Why are fish in rigor mortis unsuitable for processing?
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What does the breakdown of ATP in post-mortem fish muscle indicate?
What does the breakdown of ATP in post-mortem fish muscle indicate?
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Which nucleotide is associated with the desirable fresh fish flavor?
Which nucleotide is associated with the desirable fresh fish flavor?
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What happens to the water-holding capacity of fish muscle as post-mortem pH drops?
What happens to the water-holding capacity of fish muscle as post-mortem pH drops?
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According to the autolytic changes after death, which compound is one of the first to degrade?
According to the autolytic changes after death, which compound is one of the first to degrade?
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What does the term 'rigor mortis' refer to in fish muscle?
What does the term 'rigor mortis' refer to in fish muscle?
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What is a consequence of muscle tissue being in rigor mortis during processing?
What is a consequence of muscle tissue being in rigor mortis during processing?
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Which factor does NOT affect the levels of stored glycogen in fish before death?
Which factor does NOT affect the levels of stored glycogen in fish before death?
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What occurs during the resolution of rigor in fish muscle?
What occurs during the resolution of rigor in fish muscle?
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What is the role of the TMAO-ase enzyme in fish?
What is the role of the TMAO-ase enzyme in fish?
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What can minimize the production of formaldehyde during frozen storage of fish?
What can minimize the production of formaldehyde during frozen storage of fish?
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Which organ in gadoid fishes is primarily associated with the presence of TMAO demethylase?
Which organ in gadoid fishes is primarily associated with the presence of TMAO demethylase?
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What impact does rough handling of fish during capture have on their quality?
What impact does rough handling of fish during capture have on their quality?
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The softening of tissue due to collagenases is primarily associated with which factor?
The softening of tissue due to collagenases is primarily associated with which factor?
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Which of the following statements about the production of formaldehyde in fish is accurate?
Which of the following statements about the production of formaldehyde in fish is accurate?
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What is one critical factor in preventing 'gaping' of fish fillets during storage?
What is one critical factor in preventing 'gaping' of fish fillets during storage?
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In terms of muscle activity, how does dark muscle differ from white muscle in gadoid fish?
In terms of muscle activity, how does dark muscle differ from white muscle in gadoid fish?
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What is a recommended practice to minimize the toughening of hake muscle during frozen storage?
What is a recommended practice to minimize the toughening of hake muscle during frozen storage?
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Which enzyme class is responsible for the softening of connective tissues in fish?
Which enzyme class is responsible for the softening of connective tissues in fish?
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What is indicated by the equal rates of formation and breakdown of IMP in sterile and non-sterile cod tissue?
What is indicated by the equal rates of formation and breakdown of IMP in sterile and non-sterile cod tissue?
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What effect does physical handling have on autolytic changes in chilled fish?
What effect does physical handling have on autolytic changes in chilled fish?
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What role does bacterial nucleoside phosphorylase play in refrigerated cod?
What role does bacterial nucleoside phosphorylase play in refrigerated cod?
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Which enzyme is primarily responsible for the degradation of ATP through to inosine?
Which enzyme is primarily responsible for the degradation of ATP through to inosine?
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What is a consequence of the autolysis of fish muscle tissue?
What is a consequence of the autolysis of fish muscle tissue?
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Which factors primarily influence belly-bursting in herring?
Which factors primarily influence belly-bursting in herring?
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What characteristic is associated with the cathepsins found in fish tissues?
What characteristic is associated with the cathepsins found in fish tissues?
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What is the effect of autolytic proteolysis on pelagic fish during the summer months?
What is the effect of autolytic proteolysis on pelagic fish during the summer months?
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Which of the following is NOT a factor in the rates of nucleotide degradation among different fish species?
Which of the following is NOT a factor in the rates of nucleotide degradation among different fish species?
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Which proteolytic enzymes have been investigated for their role in fish tissue breakdown?
Which proteolytic enzymes have been investigated for their role in fish tissue breakdown?
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Which process can inhibit proteolysis in fish muscle tissue?
Which process can inhibit proteolysis in fish muscle tissue?
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What pH range do cathepsin D enzymes predominantly exhibit activity?
What pH range do cathepsin D enzymes predominantly exhibit activity?
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What was a significant finding related to nucleotide breakdown rates in bulk-stored herring for fishmeal?
What was a significant finding related to nucleotide breakdown rates in bulk-stored herring for fishmeal?
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Why is it important to store iced fish in boxes that are not deeper than 30 cm?
Why is it important to store iced fish in boxes that are not deeper than 30 cm?
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Which statement is true regarding the activity of cathepsins in fish tissues?
Which statement is true regarding the activity of cathepsins in fish tissues?
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What is the primary reason cathepsin L is implicated in the softening of salmon muscle during spawning?
What is the primary reason cathepsin L is implicated in the softening of salmon muscle during spawning?
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Why is it unlikely that Reddi's enzyme was active in salted fish products?
Why is it unlikely that Reddi's enzyme was active in salted fish products?
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How does freezing and thawing affect autolytic enzyme activity in fish muscles?
How does freezing and thawing affect autolytic enzyme activity in fish muscles?
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Which enzymes are primarily responsible for the post mortem autolysis of meat?
Which enzymes are primarily responsible for the post mortem autolysis of meat?
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What effect does cathepsin L activity have on muscle texture during the fermentation process of fish products?
What effect does cathepsin L activity have on muscle texture during the fermentation process of fish products?
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Which type of collagen has been linked to the gaping or breakdown of myotomes during long-term storage of fish?
Which type of collagen has been linked to the gaping or breakdown of myotomes during long-term storage of fish?
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How does calpain activity in fish compare to that in mammalian muscle?
How does calpain activity in fish compare to that in mammalian muscle?
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What is the significance of calcium in the activity of calpains?
What is the significance of calcium in the activity of calpains?
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Which statement accurately describes the role of collagenases in fish?
Which statement accurately describes the role of collagenases in fish?
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What happens to tropical fish species in terms of calpain autolysis compared to those adapted to colder environments?
What happens to tropical fish species in terms of calpain autolysis compared to those adapted to colder environments?
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Which major consequence does high calpain activity have on the quality of fish muscle?
Which major consequence does high calpain activity have on the quality of fish muscle?
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What is a significant factor influencing calpain activity in fish species?
What is a significant factor influencing calpain activity in fish species?
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What is one of the attributes of proteolytic enzymes in parasitized Pacific hake muscle?
What is one of the attributes of proteolytic enzymes in parasitized Pacific hake muscle?
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What notable difference exists between myosins in fish and mammals concerning calpain action?
What notable difference exists between myosins in fish and mammals concerning calpain action?
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What is the first sensory change in fish during storage?
What is the first sensory change in fish during storage?
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What condition does fish undergo immediately after death?
What condition does fish undergo immediately after death?
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How does high temperature affect the onset of rigor mortis in cod?
How does high temperature affect the onset of rigor mortis in cod?
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Which factor does NOT affect the rate of onset and resolution of rigor mortis?
Which factor does NOT affect the rate of onset and resolution of rigor mortis?
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What physiological change occurs in the fish muscle after rigor mortis resolves?
What physiological change occurs in the fish muscle after rigor mortis resolves?
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What is the relationship between temperature and the onset of rigor mortis in certain tropical fish?
What is the relationship between temperature and the onset of rigor mortis in certain tropical fish?
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What can be a consequence of strong rigor tensions in fish?
What can be a consequence of strong rigor tensions in fish?
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What does the onset of rigor mortis depend on in carp, according to research?
What does the onset of rigor mortis depend on in carp, according to research?
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What effect does stress have on the onset of rigor mortis in fish?
What effect does stress have on the onset of rigor mortis in fish?
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How does the method of stunning affect rigor mortis in fish?
How does the method of stunning affect rigor mortis in fish?
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What happens to muscle contraction when fish are filleted pre-rigor?
What happens to muscle contraction when fish are filleted pre-rigor?
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Which of the following best describes the texture of fish cooked post-rigor?
Which of the following best describes the texture of fish cooked post-rigor?
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What does the onset time of rigor mortis depend on?
What does the onset time of rigor mortis depend on?
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What phase indicates the fish has become spoiled and putrid?
What phase indicates the fish has become spoiled and putrid?
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What is the effect of cooking fish in rigor compared to cooking pre-rigor?
What is the effect of cooking fish in rigor compared to cooking pre-rigor?
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During which phase does the fish begin to lose its characteristic odour and taste?
During which phase does the fish begin to lose its characteristic odour and taste?
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What is the maximum shrinkage of dark muscle according to the content?
What is the maximum shrinkage of dark muscle according to the content?
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What happens during the cooking of fillets removed pre-rigor?
What happens during the cooking of fillets removed pre-rigor?
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What condition indicates a fish is in a ‘1’ state for flesh inspection based on its surface characteristics?
What condition indicates a fish is in a ‘1’ state for flesh inspection based on its surface characteristics?
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Which of the following statements about the appearance of fish before and after storage is true?
Which of the following statements about the appearance of fish before and after storage is true?
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In the context of fish freshness, which gill condition would indicate a decline in quality?
In the context of fish freshness, which gill condition would indicate a decline in quality?
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Which assessment method should be conducted to determine the quality of chilled fish during storage?
Which assessment method should be conducted to determine the quality of chilled fish during storage?
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Which aspect of the fish's visual inspection should be evaluated first for overall quality assessment?
Which aspect of the fish's visual inspection should be evaluated first for overall quality assessment?
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Which of the following factors is NOT relevant when assessing the condition of the fish's flesh?
Which of the following factors is NOT relevant when assessing the condition of the fish's flesh?
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What is the correct pH range of cod muscle during post mortem changes?
What is the correct pH range of cod muscle during post mortem changes?
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What physiological change occurs in fish muscle tissue shortly after death?
What physiological change occurs in fish muscle tissue shortly after death?
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Which of the following is a characteristic of autolytic changes in fish spoilage?
Which of the following is a characteristic of autolytic changes in fish spoilage?
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How does internal energy production in fish muscles occur after death?
How does internal energy production in fish muscles occur after death?
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Which of the following pathways is NOT involved in ATP production in post mortem fish muscle?
Which of the following pathways is NOT involved in ATP production in post mortem fish muscle?
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What happens to the freshness indicators of fish when they fall below a sensory evaluation score of 4?
What happens to the freshness indicators of fish when they fall below a sensory evaluation score of 4?
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What characteristic is used to describe a ‘1’ state in the eye inspection of fish?
What characteristic is used to describe a ‘1’ state in the eye inspection of fish?
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What is the significance of the bright red color of the kidneys and other organs in fish?
What is the significance of the bright red color of the kidneys and other organs in fish?
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What effect does rigorous post mortem handling have on fish tissue?
What effect does rigorous post mortem handling have on fish tissue?
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What is the primary enzyme responsible for autolysis in salmon muscle during spawning?
What is the primary enzyme responsible for autolysis in salmon muscle during spawning?
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How does sodium chloride (NaCl) affect enzyme activity in the context of fish muscle?
How does sodium chloride (NaCl) affect enzyme activity in the context of fish muscle?
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Which statement best describes the relationship between cathepsin L activity and the texture of fish muscle?
Which statement best describes the relationship between cathepsin L activity and the texture of fish muscle?
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What role do calpains play in the texture changes of fish muscle?
What role do calpains play in the texture changes of fish muscle?
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Which factor is most likely to enhance autolytic activity in fish muscle during storage?
Which factor is most likely to enhance autolytic activity in fish muscle during storage?
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What is the effect of high temperature on connective tissue in fish muscle?
What is the effect of high temperature on connective tissue in fish muscle?
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What distinguishes fish calpains from mammalian calpains?
What distinguishes fish calpains from mammalian calpains?
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Which enzyme is implicated in the jelly-like softening of flounder muscle?
Which enzyme is implicated in the jelly-like softening of flounder muscle?
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What is a primary characteristic of the degradation process mediated by collagenases in fish muscle?
What is a primary characteristic of the degradation process mediated by collagenases in fish muscle?
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What are the primary conditions that activate calpains in fish?
What are the primary conditions that activate calpains in fish?
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What is the effect of the presence of catheptic enzymes on fermented fish products?
What is the effect of the presence of catheptic enzymes on fermented fish products?
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In terms of fish autolysis, how do myofibrillar proteins contribute to muscle texture?
In terms of fish autolysis, how do myofibrillar proteins contribute to muscle texture?
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What role does the degradation of type V collagen play in the texture of fish muscle?
What role does the degradation of type V collagen play in the texture of fish muscle?
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What is the primary enzyme responsible for the toughening of frozen gadoid fish?
What is the primary enzyme responsible for the toughening of frozen gadoid fish?
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Which factor significantly accelerates the breakdown of fish flavor due to nucleotide degradation?
Which factor significantly accelerates the breakdown of fish flavor due to nucleotide degradation?
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How can toughening of frozen fish muscle be minimized during storage?
How can toughening of frozen fish muscle be minimized during storage?
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What change occurs in chilled prawns due to collagenase enzymes?
What change occurs in chilled prawns due to collagenase enzymes?
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What is the byproduct of TMAO breakdown that poses a greater commercial significance?
What is the byproduct of TMAO breakdown that poses a greater commercial significance?
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In which tissue is TMAO demethylase most commonly found?
In which tissue is TMAO demethylase most commonly found?
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What condition leads to high levels of formaldehyde production in frozen fish storage?
What condition leads to high levels of formaldehyde production in frozen fish storage?
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What is a consequence of the physical disruption of muscle cells in fish?
What is a consequence of the physical disruption of muscle cells in fish?
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How does dark muscle differ from white muscle in terms of TMAO demethylase activity?
How does dark muscle differ from white muscle in terms of TMAO demethylase activity?
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Which of the following is NOT a factor involved in autolytic changes affecting fish edibility?
Which of the following is NOT a factor involved in autolytic changes affecting fish edibility?
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What is the main factor that influences the ultimate post mortem pH in fish?
What is the main factor that influences the ultimate post mortem pH in fish?
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Which fish species is noted for having particularly low ultimate rigor pH levels?
Which fish species is noted for having particularly low ultimate rigor pH levels?
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What happens to the muscle protein's water-holding capacity as post mortem pH decreases?
What happens to the muscle protein's water-holding capacity as post mortem pH decreases?
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What happens to fish muscle as rigor mortis sets in?
What happens to fish muscle as rigor mortis sets in?
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What is associated with the undesirable texture of fish muscle when the pH is low?
What is associated with the undesirable texture of fish muscle when the pH is low?
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How does bleeding fish affect lactic acid production post mortem?
How does bleeding fish affect lactic acid production post mortem?
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What is the consequence of a fish being stressed prior to capture in terms of its pH level?
What is the consequence of a fish being stressed prior to capture in terms of its pH level?
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Which nucleotide catabolite is primarily associated with the desirable flavor of fresh fish?
Which nucleotide catabolite is primarily associated with the desirable flavor of fresh fish?
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What aspect of nucleotide degradation is considered unreliable for measuring fish freshness?
What aspect of nucleotide degradation is considered unreliable for measuring fish freshness?
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What is the primary role of ATP in muscle contractions?
What is the primary role of ATP in muscle contractions?
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Which change is NOT typically observed in fish muscle during autolysis?
Which change is NOT typically observed in fish muscle during autolysis?
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What enzyme is primarily involved in muscle contraction and is affected during rigor mortis?
What enzyme is primarily involved in muscle contraction and is affected during rigor mortis?
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What can significantly affect the physical properties of fish muscle post mortem?
What can significantly affect the physical properties of fish muscle post mortem?
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Which enzyme is primarily responsible for the conversion of Iino to Hx in non-sterile cod samples?
Which enzyme is primarily responsible for the conversion of Iino to Hx in non-sterile cod samples?
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What is the main consequence of physical handling on chilled fish?
What is the main consequence of physical handling on chilled fish?
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What effect do autolytic processes have on fish used for fishmeal production?
What effect do autolytic processes have on fish used for fishmeal production?
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What is a notable consequence of belly-bursting in pelagic fish species?
What is a notable consequence of belly-bursting in pelagic fish species?
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Which factor was found to influence belly-bursting in herring the most?
Which factor was found to influence belly-bursting in herring the most?
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What is the primary role of cathepsins in fish tissue?
What is the primary role of cathepsins in fish tissue?
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What impact does autolysis have on the nutritional value of fish?
What impact does autolysis have on the nutritional value of fish?
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What is one method that has been shown to inhibit proteolysis in fish?
What is one method that has been shown to inhibit proteolysis in fish?
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How does the activity of proteolytic enzymes change after physical abuse to fish?
How does the activity of proteolytic enzymes change after physical abuse to fish?
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How does the degradation of nucleotide catabolites differ between sterile and non-sterile cod fillets?
How does the degradation of nucleotide catabolites differ between sterile and non-sterile cod fillets?
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What is a key reason to avoid stacking fish boxes too deeply?
What is a key reason to avoid stacking fish boxes too deeply?
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What pH range is cathepsin D believed to be active in?
What pH range is cathepsin D believed to be active in?
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What describes the compartmentalization of autolytic enzymes in fish tissues?
What describes the compartmentalization of autolytic enzymes in fish tissues?
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What was a significant finding in the study carried out by Surette et al. (1990)?
What was a significant finding in the study carried out by Surette et al. (1990)?
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What is significantly impacted by temperature changes in the range of 0 to 25°C?
What is significantly impacted by temperature changes in the range of 0 to 25°C?
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Which temperature condition results in minimal growth for many bacteria?
Which temperature condition results in minimal growth for many bacteria?
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What is the primary reason for extending the shelf life of fish products?
What is the primary reason for extending the shelf life of fish products?
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What is the impact of storing fresh fish in ice at 0°C?
What is the impact of storing fresh fish in ice at 0°C?
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What does the relative rate of spoilage (RRS) depict with regard to fish storage?
What does the relative rate of spoilage (RRS) depict with regard to fish storage?
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At which temperature do many bacteria begin to have significantly reduced growth rates?
At which temperature do many bacteria begin to have significantly reduced growth rates?
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Why do psychrotrophic organisms show slow growth at low temperatures?
Why do psychrotrophic organisms show slow growth at low temperatures?
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In industrialized countries, how is fresh fish typically preserved at low temperatures?
In industrialized countries, how is fresh fish typically preserved at low temperatures?
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What effect does temperature have on the relative rate of spoilage (RRS) of seafood products?
What effect does temperature have on the relative rate of spoilage (RRS) of seafood products?
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Which microflora are primarily responsible for seafood spoilage at low temperatures (0-5°C)?
Which microflora are primarily responsible for seafood spoilage at low temperatures (0-5°C)?
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Which spoilage model is suggested by Ratkowsky et al. for sub-optimal temperatures?
Which spoilage model is suggested by Ratkowsky et al. for sub-optimal temperatures?
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What is the predicted relative rate of spoilage (RRS) for typical tropical fish stored at 25°C compared to 0°C?
What is the predicted relative rate of spoilage (RRS) for typical tropical fish stored at 25°C compared to 0°C?
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What is the effect of temperature history in fish storage as indicated by temperature loggers?
What is the effect of temperature history in fish storage as indicated by temperature loggers?
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What happens to the RRS of packed fresh fish and superchilled fresh fish products?
What happens to the RRS of packed fresh fish and superchilled fresh fish products?
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Why was the Arrhenius Equation deemed inaccurate for predicting spoilage rates?
Why was the Arrhenius Equation deemed inaccurate for predicting spoilage rates?
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Which temperature range hosts the highest variety of spoilage species for fish?
Which temperature range hosts the highest variety of spoilage species for fish?
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What cumulative effect does temperature have on seafood effectively predicted by spoilage models?
What cumulative effect does temperature have on seafood effectively predicted by spoilage models?
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What is the theoretical minimum temperature for growth of psychrotrophic bacteria according to research?
What is the theoretical minimum temperature for growth of psychrotrophic bacteria according to research?
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Which factor limits the practical usage of electronic time/temperature function integrators for predicting RRS?
Which factor limits the practical usage of electronic time/temperature function integrators for predicting RRS?
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Which of the following spoilage models incorporates a relative rate concept?
Which of the following spoilage models incorporates a relative rate concept?
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Which organism primarily causes spoilage at elevated temperatures (15-30°C)?
Which organism primarily causes spoilage at elevated temperatures (15-30°C)?
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What negative effect has been observed with superchilling certain fish species?
What negative effect has been observed with superchilling certain fish species?
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How does the temperature affect the percentage of frozen water in superchilled fish?
How does the temperature affect the percentage of frozen water in superchilled fish?
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What conclusion can be drawn about the importance of hygiene during onboard handling of fish?
What conclusion can be drawn about the importance of hygiene during onboard handling of fish?
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What was observed regarding the organoleptic quality of fish after different handling procedures?
What was observed regarding the organoleptic quality of fish after different handling procedures?
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What factor significantly affects the shelf life of superchilled shrimp compared to cod?
What factor significantly affects the shelf life of superchilled shrimp compared to cod?
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Which storage temperature led to increased drip loss in superchilled cod?
Which storage temperature led to increased drip loss in superchilled cod?
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What has been suggested regarding the construction of fish boxes for chilling purposes?
What has been suggested regarding the construction of fish boxes for chilling purposes?
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Which method has been considered for prolonging storage life by reducing bacterial counts?
Which method has been considered for prolonging storage life by reducing bacterial counts?
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What relationship was established between bacterial contamination and fish storage life?
What relationship was established between bacterial contamination and fish storage life?
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What effect does lowering the pH have on muscle proteins in fish?
What effect does lowering the pH have on muscle proteins in fish?
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What was the observed impact of the superchilling technique on mackerel storage at -3°C?
What was the observed impact of the superchilling technique on mackerel storage at -3°C?
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What is the primary impact of temperature on the shelf life of fish products?
What is the primary impact of temperature on the shelf life of fish products?
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Which of the following statements is true regarding the effects of RSW storage?
Which of the following statements is true regarding the effects of RSW storage?
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Which fish products are noted as having increased drip loss when stored in high CO2 concentrations?
Which fish products are noted as having increased drip loss when stored in high CO2 concentrations?
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What is a significant negative effect of storing fish in 100% CO2?
What is a significant negative effect of storing fish in 100% CO2?
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Why is it challenging to unload fish when heat exchanges are used on vessels?
Why is it challenging to unload fish when heat exchanges are used on vessels?
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Which factor does NOT influence the rate of spoilage in fish?
Which factor does NOT influence the rate of spoilage in fish?
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How does the demerit point system relate to fish quality assessment?
How does the demerit point system relate to fish quality assessment?
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What is a consequence of the ice crystals formed during superchilling in fish?
What is a consequence of the ice crystals formed during superchilling in fish?
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How does the addition of CO2 to refrigerated seawater (RSW) influence the shelf life of pink shrimps?
How does the addition of CO2 to refrigerated seawater (RSW) influence the shelf life of pink shrimps?
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What has research indicated about the sensory quality of fish stored using superchilling methods?
What has research indicated about the sensory quality of fish stored using superchilling methods?
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What is the effect of exposure to high temperatures before chilling on white-fleshed fish?
What is the effect of exposure to high temperatures before chilling on white-fleshed fish?
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What is a common problem associated with CO2 in RSW systems?
What is a common problem associated with CO2 in RSW systems?
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What is superchilling in fish storage?
What is superchilling in fish storage?
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Which of the following bacteria is noted to exhibit increased toxin production in anaerobic conditions?
Which of the following bacteria is noted to exhibit increased toxin production in anaerobic conditions?
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Which equation is used to determine the shelf life of fish at different temperatures based on initial quality?
Which equation is used to determine the shelf life of fish at different temperatures based on initial quality?
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What happens to fish that are not gutted before storage?
What happens to fish that are not gutted before storage?
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What impact does CO2 have on the color of fish stored in high concentrations?
What impact does CO2 have on the color of fish stored in high concentrations?
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What is a common effect of lipid oxidation in fish?
What is a common effect of lipid oxidation in fish?
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What was the suggestion made by Spencer and Baines regarding fish spoilage?
What was the suggestion made by Spencer and Baines regarding fish spoilage?
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How does the production of TMA in fish products during MAP compare to traditional storage methods?
How does the production of TMA in fish products during MAP compare to traditional storage methods?
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What role does the Frigido-system serve in fish storage?
What role does the Frigido-system serve in fish storage?
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Why has modified atmosphere packaging (MAP) found less practical application with fish products compared to meats?
Why has modified atmosphere packaging (MAP) found less practical application with fish products compared to meats?
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What is primarily affected by CO2 levels in fish storage?
What is primarily affected by CO2 levels in fish storage?
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Which temperature range is associated with the square root spoilage model?
Which temperature range is associated with the square root spoilage model?
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What is a major consequence of delayed chilling for fatty fish?
What is a major consequence of delayed chilling for fatty fish?
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For which type of fish is the negative impact of CO2 on color and texture less critical?
For which type of fish is the negative impact of CO2 on color and texture less critical?
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How does the storage system using refrigerated sea water (RSW) benefit fish storage?
How does the storage system using refrigerated sea water (RSW) benefit fish storage?
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What is the best description of the overall effect of CO2 on fish stored in RSW?
What is the best description of the overall effect of CO2 on fish stored in RSW?
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What common problem occurs when white-fleshed fish are not chilled properly?
What common problem occurs when white-fleshed fish are not chilled properly?
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What is a consequence of the strong digestive enzymes present in fish prior to gutting?
What is a consequence of the strong digestive enzymes present in fish prior to gutting?
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What importance does initial product quality hold in temperature spoilage models?
What importance does initial product quality hold in temperature spoilage models?
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What is the approximate shelf life range of tropical marine fish when stored in ice?
What is the approximate shelf life range of tropical marine fish when stored in ice?
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Which fish type has the longest shelf life according to the provided data?
Which fish type has the longest shelf life according to the provided data?
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Which of the following species has a shelf life that exceeds 20 days when stored in ice?
Which of the following species has a shelf life that exceeds 20 days when stored in ice?
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Which factor significantly influences the shelf life of fish in iced storage?
Which factor significantly influences the shelf life of fish in iced storage?
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Which species has the shortest shelf life in ice according to the data provided?
Which species has the shortest shelf life in ice according to the data provided?
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What is the primary bacterial group responsible for spoilage in iced stored fish?
What is the primary bacterial group responsible for spoilage in iced stored fish?
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Which characteristic is used to differentiate spoilage between temperate and tropical fish?
Which characteristic is used to differentiate spoilage between temperate and tropical fish?
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Which marine fish species can last between 21 and 26 days in iced storage?
Which marine fish species can last between 21 and 26 days in iced storage?
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What role does pH play in the shelf life of fish?
What role does pH play in the shelf life of fish?
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What common misconception may arise regarding the spoilage rates between tropical and temperate fish?
What common misconception may arise regarding the spoilage rates between tropical and temperate fish?
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What aspect of tropical fish spoilage has been proposed as having less impact than previously thought?
What aspect of tropical fish spoilage has been proposed as having less impact than previously thought?
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What is a notable biochemical characteristic of spoilage in Shewanella-dominated fish?
What is a notable biochemical characteristic of spoilage in Shewanella-dominated fish?
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What is often observed about the shelf life of freshwater fish compared to marine species?
What is often observed about the shelf life of freshwater fish compared to marine species?
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What conclusion did Lima dos Santos reach regarding the shelf life of temperate versus tropical fish?
What conclusion did Lima dos Santos reach regarding the shelf life of temperate versus tropical fish?
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What effect does high CO2 concentration have on microbial growth in food products?
What effect does high CO2 concentration have on microbial growth in food products?
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Which method has been shown to effectively extend the shelf life of fish?
Which method has been shown to effectively extend the shelf life of fish?
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What is a primary concern of using chlorinated water for washing fish?
What is a primary concern of using chlorinated water for washing fish?
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What types of microorganisms dominate the spoilage of vacuum packed (VP) meat products?
What types of microorganisms dominate the spoilage of vacuum packed (VP) meat products?
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Why does modified atmosphere packaging (MAP) have limited effect on the shelf life of fresh fish?
Why does modified atmosphere packaging (MAP) have limited effect on the shelf life of fresh fish?
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What happens to the pH level of fish flesh stored in CO2 packed conditions?
What happens to the pH level of fish flesh stored in CO2 packed conditions?
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Which of the following fish species is generally better suited for MAP storage?
Which of the following fish species is generally better suited for MAP storage?
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What is the spoilage organism primarily responsible for packed cod spoilage?
What is the spoilage organism primarily responsible for packed cod spoilage?
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What common reaction is caused by the metabolic activity of Photobacterium phosphoreum in spoiled fish?
What common reaction is caused by the metabolic activity of Photobacterium phosphoreum in spoiled fish?
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How does the spoilage microflora differ between meat and fish?
How does the spoilage microflora differ between meat and fish?
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What is the primary reason that washing fish in clean seawater is conducted?
What is the primary reason that washing fish in clean seawater is conducted?
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What is a disadvantage of using antibiotics in fish storage methods?
What is a disadvantage of using antibiotics in fish storage methods?
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What is the characteristic growth response of Shewanella putrefaciens in CO2-rich environments?
What is the characteristic growth response of Shewanella putrefaciens in CO2-rich environments?
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Which factor contributes to the relatively short shelf lives of aquatic products compared to meat?
Which factor contributes to the relatively short shelf lives of aquatic products compared to meat?
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What primarily contributes to the longer shelf life of tropical fish according to the findings?
What primarily contributes to the longer shelf life of tropical fish according to the findings?
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How does the bacterial growth profile of tropical fish differ from that of temperate water fish?
How does the bacterial growth profile of tropical fish differ from that of temperate water fish?
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What is the significance of psychrotrophic organisms on iced tropical fish?
What is the significance of psychrotrophic organisms on iced tropical fish?
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Which group of bacteria is often found dominating tropical fish caught in warm waters?
Which group of bacteria is often found dominating tropical fish caught in warm waters?
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What can cause an off-flavour described as 'mineral oil' in certain fish?
What can cause an off-flavour described as 'mineral oil' in certain fish?
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Which compound is primarily responsible for the muddy-earthy taint in freshwater fish?
Which compound is primarily responsible for the muddy-earthy taint in freshwater fish?
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What factor has a significant impact on the shelf life of fish according to the findings?
What factor has a significant impact on the shelf life of fish according to the findings?
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What happens to the bacterial composition in areas with fluctuating temperatures, according to the findings?
What happens to the bacterial composition in areas with fluctuating temperatures, according to the findings?
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What is the cause of the iodine-like flavour found in some marine fish?
What is the cause of the iodine-like flavour found in some marine fish?
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Which type of bacteria has shown to grow more quickly at lower temperatures if pre-cultured at moderate temperatures?
Which type of bacteria has shown to grow more quickly at lower temperatures if pre-cultured at moderate temperatures?
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Which of the following is a plausible reason for fish spoilage at rates similar to temperate water fish?
Which of the following is a plausible reason for fish spoilage at rates similar to temperate water fish?
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What is a common reason for off-flavours in fish related to oil spills?
What is a common reason for off-flavours in fish related to oil spills?
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During which specific condition can a significant bacterial lag phase for tropical fish occur?
During which specific condition can a significant bacterial lag phase for tropical fish occur?
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Which of the following bacteria is known to predominantly thrive on iced cod?
Which of the following bacteria is known to predominantly thrive on iced cod?
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What is a key characteristic of the bacteria found in Narragansett Bay over a 2-year period?
What is a key characteristic of the bacteria found in Narragansett Bay over a 2-year period?
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What is one reason why small- and medium-sized fatty fish are not typically gutted immediately after being caught?
What is one reason why small- and medium-sized fatty fish are not typically gutted immediately after being caught?
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How does gutting affect the quality of lean fish like cod?
How does gutting affect the quality of lean fish like cod?
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Which type of fish is reported to be unaffected by whether it is gutted or ungutted?
Which type of fish is reported to be unaffected by whether it is gutted or ungutted?
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What has been found to contribute to the occurrence of belly-burst in ungutted fish?
What has been found to contribute to the occurrence of belly-burst in ungutted fish?
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Which factor does NOT influence the spoilage rate of fish?
Which factor does NOT influence the spoilage rate of fish?
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What is a primary characteristic that typically affects the shelf life of fatty fish compared to lean fish?
What is a primary characteristic that typically affects the shelf life of fatty fish compared to lean fish?
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What is the observed effect on the pH level of well-fed fish post mortem?
What is the observed effect on the pH level of well-fed fish post mortem?
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Which type of fish is generally associated with a longer shelf life when stored in ice?
Which type of fish is generally associated with a longer shelf life when stored in ice?
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What specific issue is specifically linked to rough handling of fish post-catch?
What specific issue is specifically linked to rough handling of fish post-catch?
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In terms of spoilage rates, how do larger fish generally compare to smaller fish?
In terms of spoilage rates, how do larger fish generally compare to smaller fish?
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Which of the following characteristics is most commonly associated with fatty pelagic fish that affects their spoilage rate?
Which of the following characteristics is most commonly associated with fatty pelagic fish that affects their spoilage rate?
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What is the effect of the type of feed ingested by fish on their quality?
What is the effect of the type of feed ingested by fish on their quality?
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What is a common misconception about the influence of fish species on spoilage rates?
What is a common misconception about the influence of fish species on spoilage rates?
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Which factor is NOT considered when determining the advantages of gutting fish?
Which factor is NOT considered when determining the advantages of gutting fish?
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What is the primary effect of chill storage temperatures on microbiological activity?
What is the primary effect of chill storage temperatures on microbiological activity?
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At which temperature do many bacteria begin to show an inability to grow?
At which temperature do many bacteria begin to show an inability to grow?
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How does the growth rate of Shewanella Putrefaciens at 0°C compare to its optimum growth temperature?
How does the growth rate of Shewanella Putrefaciens at 0°C compare to its optimum growth temperature?
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What is the typical storage temperature range for extending the shelf life of fish products?
What is the typical storage temperature range for extending the shelf life of fish products?
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What is the concept of relative rate of spoilage (RRS) in relation to fish storage?
What is the concept of relative rate of spoilage (RRS) in relation to fish storage?
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What is the impact of low-temperature storage on the shelf life of fish products?
What is the impact of low-temperature storage on the shelf life of fish products?
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Which of the following best describes the lag phase of psychrotrophic organisms at low temperatures?
Which of the following best describes the lag phase of psychrotrophic organisms at low temperatures?
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Which statement is true regarding the relationship between temperature and microbiological growth?
Which statement is true regarding the relationship between temperature and microbiological growth?
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What is the shelf life of crab claws stored at 10°C according to the provided data?
What is the shelf life of crab claws stored at 10°C according to the provided data?
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What growth characteristic of microorganisms is suggested when using the square root spoilage model?
What growth characteristic of microorganisms is suggested when using the square root spoilage model?
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Which of the following fish is noted to have a significantly longer shelf life at 0°C compared to others?
Which of the following fish is noted to have a significantly longer shelf life at 0°C compared to others?
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What is the Arrhenius Equation used to describe?
What is the Arrhenius Equation used to describe?
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What type of bacteria is primarily responsible for spoilage at low temperatures (0-5°C)?
What type of bacteria is primarily responsible for spoilage at low temperatures (0-5°C)?
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Which spoilage model is mentioned as giving good estimates of temperature effects on bacteria?
Which spoilage model is mentioned as giving good estimates of temperature effects on bacteria?
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Which spoilage factor is NOT accounted for by Equation 6.c?
Which spoilage factor is NOT accounted for by Equation 6.c?
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Which model allows prediction of the effect of variable temperatures on product keepability?
Which model allows prediction of the effect of variable temperatures on product keepability?
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What is the primary limitation of the electronic time/temperature function integrator?
What is the primary limitation of the electronic time/temperature function integrator?
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How does the relative rate of spoilage for tropical fish compare to that of fish stored at lower temperatures?
How does the relative rate of spoilage for tropical fish compare to that of fish stored at lower temperatures?
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What is the theorized minimum temperature for microbial growth according to research on psychrotrophic bacteria?
What is the theorized minimum temperature for microbial growth according to research on psychrotrophic bacteria?
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What is the effect of temperature on seafood spoilage described as?
What is the effect of temperature on seafood spoilage described as?
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What historical research influenced the understanding of spoilage rates and temperature effects?
What historical research influenced the understanding of spoilage rates and temperature effects?
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What method has been rejected due to public health concerns for treating fish?
What method has been rejected due to public health concerns for treating fish?
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Which treatment method has shown success in extending the shelf life of fish?
Which treatment method has shown success in extending the shelf life of fish?
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What is the effect of chlorine when used for washing fish?
What is the effect of chlorine when used for washing fish?
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Which packaging method has the least increase in shelf life for fresh fish?
Which packaging method has the least increase in shelf life for fresh fish?
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What organisms are primarily responsible for spoilage of packed meat under anaerobic conditions?
What organisms are primarily responsible for spoilage of packed meat under anaerobic conditions?
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What key factor distinguishes spoilage in packed fish compared to packed meat?
What key factor distinguishes spoilage in packed fish compared to packed meat?
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Which Gram-negative organism is associated with spoilage of packed cod?
Which Gram-negative organism is associated with spoilage of packed cod?
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What effect does CO2 have on Shewanella putrefaciens in packed fish?
What effect does CO2 have on Shewanella putrefaciens in packed fish?
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What effect does increased CO2 concentration have on the water-holding capacity of muscle proteins?
What effect does increased CO2 concentration have on the water-holding capacity of muscle proteins?
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Which factor contributes to the relatively short shelf life of warmwater fish compared to other meat products?
Which factor contributes to the relatively short shelf life of warmwater fish compared to other meat products?
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Which fish species showed no significant increase in drip loss when stored in high CO2 concentrations?
Which fish species showed no significant increase in drip loss when stored in high CO2 concentrations?
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What is a non-microbial factor that might influence spoilage in packed fish?
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How does storage in RSW + CO2 influence the shelf life of pink shrimp compared to ice storage?
How does storage in RSW + CO2 influence the shelf life of pink shrimp compared to ice storage?
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What negative effect can result from the addition of CO2 to RSW systems?
What negative effect can result from the addition of CO2 to RSW systems?
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How does CO2 affect the pH of MAP fish during storage?
How does CO2 affect the pH of MAP fish during storage?
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What is a common outcome of the spoilage pattern in packed cod?
What is a common outcome of the spoilage pattern in packed cod?
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What does CO2 do to the pH of seawater, and what is the impact on enzymatic reactions?
What does CO2 do to the pH of seawater, and what is the impact on enzymatic reactions?
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What characteristic of Photobacterium phosphoreum affects cod shelf life?
What characteristic of Photobacterium phosphoreum affects cod shelf life?
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What quality issue has been observed in whole fish stored in high CO2 concentrations?
What quality issue has been observed in whole fish stored in high CO2 concentrations?
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What is a significant factor that can lead to inaccurate shelf life predictions for fish products?
What is a significant factor that can lead to inaccurate shelf life predictions for fish products?
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What effect does MAP (Modified Atmosphere Packaging) have on seafood compared to meat products?
What effect does MAP (Modified Atmosphere Packaging) have on seafood compared to meat products?
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Which bacteria's toxin production may be increased due to anaerobic conditions in packed fish?
Which bacteria's toxin production may be increased due to anaerobic conditions in packed fish?
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Which model predicts the shelf life of fish at different temperatures based on the relative rate concept?
Which model predicts the shelf life of fish at different temperatures based on the relative rate concept?
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Which fish species may become unsuitable for canning due to CO2 dissolving in the flesh?
Which fish species may become unsuitable for canning due to CO2 dissolving in the flesh?
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How does rapid chilling affect the quality of fatty fish?
How does rapid chilling affect the quality of fatty fish?
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What negative effect has been observed in cod stored at -2°C compared to those stored at 0°C?
What negative effect has been observed in cod stored at -2°C compared to those stored at 0°C?
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What is a significant drawback of RSW storage for some fish species?
What is a significant drawback of RSW storage for some fish species?
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What is a possible consequence of not gutting fish before storage?
What is a possible consequence of not gutting fish before storage?
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What is the relationship between storage temperature and relative rate of spoilage for tropical fish?
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What impact does the delay before chilling have on fish quality?
What impact does the delay before chilling have on fish quality?
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What is one of the main disadvantages of using MAP for retail fish products?
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Which factor contributes to the increased drip loss in superchilled fish?
Which factor contributes to the increased drip loss in superchilled fish?
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What was the observed effect of superchilling on shrimp from Pakistan?
What was the observed effect of superchilling on shrimp from Pakistan?
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Which equation is suggested for predicting the rate of change in quality scores at different temperatures?
Which equation is suggested for predicting the rate of change in quality scores at different temperatures?
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Which type of fish was found to have improved attributes such as color and texture when stored in RSW + CO2?
Which type of fish was found to have improved attributes such as color and texture when stored in RSW + CO2?
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Which is a required material in RSW + CO2 systems due to the corrosive nature of CO2 acidifying seawater?
Which is a required material in RSW + CO2 systems due to the corrosive nature of CO2 acidifying seawater?
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What was the impact of hygiene during the initial week of storage according to the experiments conducted?
What was the impact of hygiene during the initial week of storage according to the experiments conducted?
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What storage technique can be used to extend the shelf life of various fish and shellfish?
What storage technique can be used to extend the shelf life of various fish and shellfish?
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What is a crucial factor in the demerit point system regarding fish quality?
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How does bacterial activity usually affect fish quality during storage?
How does bacterial activity usually affect fish quality during storage?
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What phenomenon occurs when white-fleshed fish enter rigor mortis at high temperatures?
What phenomenon occurs when white-fleshed fish enter rigor mortis at high temperatures?
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What design consideration for fish boxes can improve chilling efficiency?
What design consideration for fish boxes can improve chilling efficiency?
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Which method has been found to prolong storage life but is considered costly and often unacceptable?
Which method has been found to prolong storage life but is considered costly and often unacceptable?
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What system allows reduction of the ice to fish ratio in storage and improves chilling efficacy?
What system allows reduction of the ice to fish ratio in storage and improves chilling efficacy?
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Why is it important to maintain sub-zero temperatures in fishing vessels?
Why is it important to maintain sub-zero temperatures in fishing vessels?
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What is one of the main problems associated with superchilling cod and haddock?
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What can be a consequence of insufficient chilling before transport?
What can be a consequence of insufficient chilling before transport?
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What temperature range was indicated for superchilling fish, regarding the water content in frozen state?
What temperature range was indicated for superchilling fish, regarding the water content in frozen state?
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Which fish species showed improvement in shelf life due to superchilling compared to ice storage?
Which fish species showed improvement in shelf life due to superchilling compared to ice storage?
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How does delayed icing affect the yield of fish fillets?
How does delayed icing affect the yield of fish fillets?
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How does temperature influence the rate of spoilage in fish products?
How does temperature influence the rate of spoilage in fish products?
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What was the consequence of using dirty wooden boxes for fish storage?
What was the consequence of using dirty wooden boxes for fish storage?
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What did experiments indicate about the effectiveness of strict hygienic measures in fish handling?
What did experiments indicate about the effectiveness of strict hygienic measures in fish handling?
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What was one of the outcomes when comparing aseptic handling to normal handling of fish?
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What is the primary reason small and medium-sized fatty fish are often not gutted immediately after being caught?
What is the primary reason small and medium-sized fatty fish are often not gutted immediately after being caught?
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Which fish species is more likely to experience a significant reduction in quality if not gutted promptly?
Which fish species is more likely to experience a significant reduction in quality if not gutted promptly?
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What environmental factor contributes to the faster spoilage rate of fish during periods of heavy feeding?
What environmental factor contributes to the faster spoilage rate of fish during periods of heavy feeding?
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What is a key factor affecting the shelf life of fish species under aerobic storage?
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Which type of fish generally keeps longer under aerobic storage conditions?
Which type of fish generally keeps longer under aerobic storage conditions?
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What happens to the texture of ungutted fish stored on ice compared to gutted fish?
What happens to the texture of ungutted fish stored on ice compared to gutted fish?
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Which off-odor is commonly associated with ungutted fish after a short period of storage?
Which off-odor is commonly associated with ungutted fish after a short period of storage?
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What characterizes the spoilage rate when comparing bony fish with cartilaginous fish?
What characterizes the spoilage rate when comparing bony fish with cartilaginous fish?
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What may influence the accelerated rancidity in fatty fish compared to lean fish?
What may influence the accelerated rancidity in fatty fish compared to lean fish?
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Which factor plays a critical role in the quality of ungutted fish as per storage duration?
Which factor plays a critical role in the quality of ungutted fish as per storage duration?
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What is indicated by the term belly-burst in ungutted fish?
What is indicated by the term belly-burst in ungutted fish?
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What kind of change in pH occurs in well-fed fish post-mortem?
What kind of change in pH occurs in well-fed fish post-mortem?
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What type of fish is South American hake considered in terms of gutting impact?
What type of fish is South American hake considered in terms of gutting impact?
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How does the shelf life of tropical freshwater fish compare to that of marine fish from temperate waters?
How does the shelf life of tropical freshwater fish compare to that of marine fish from temperate waters?
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What bacterial species is suggested to dominate the spoilage process in iced tropical fish?
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Which statement best describes the pH levels found in tropical fish species studied?
Which statement best describes the pH levels found in tropical fish species studied?
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What is a common misconception regarding the spoilage of tropical fish?
What is a common misconception regarding the spoilage of tropical fish?
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Which factor significantly influences the shelf life of the various fish species?
Which factor significantly influences the shelf life of the various fish species?
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Which of these fish species is noted for having a longer shelf life when stored in ice?
Which of these fish species is noted for having a longer shelf life when stored in ice?
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What was the conclusion drawn by Lima dos Santos about the shelf life of temperate fish species?
What was the conclusion drawn by Lima dos Santos about the shelf life of temperate fish species?
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What is the iced shelf life range for marine fish from temperate waters?
What is the iced shelf life range for marine fish from temperate waters?
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Which of the following fish types has a documented shelf life up to 35 days when stored in ice?
Which of the following fish types has a documented shelf life up to 35 days when stored in ice?
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Which factor is often cited for the slower spoilage rates observed in certain fish species?
Which factor is often cited for the slower spoilage rates observed in certain fish species?
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What is a key difference in spoilage odors between tropical and temperate fish species?
What is a key difference in spoilage odors between tropical and temperate fish species?
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Which iced storage duration for tropical marine fish is commonly documented?
Which iced storage duration for tropical marine fish is commonly documented?
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What should be considered when comparing the shelf lives of tropical and temperate species?
What should be considered when comparing the shelf lives of tropical and temperate species?
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Which of the following factors does NOT significantly affect the iced shelf life of fish species?
Which of the following factors does NOT significantly affect the iced shelf life of fish species?
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What is the primary reason attributed to the longer iced shelf life of tropical fish?
What is the primary reason attributed to the longer iced shelf life of tropical fish?
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What is a common characteristic of the bacterial flora found on tropical fish?
What is a common characteristic of the bacterial flora found on tropical fish?
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How does the bacterial growth profile in Narragansett Bay relate to temperature fluctuations?
How does the bacterial growth profile in Narragansett Bay relate to temperature fluctuations?
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What is a noted effect of pre-culturing fish spoilage bacteria at varying temperatures?
What is a noted effect of pre-culturing fish spoilage bacteria at varying temperatures?
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What compound is responsible for the off-flavour known as 'mineral oil' in fish?
What compound is responsible for the off-flavour known as 'mineral oil' in fish?
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Which factor is often linked to the off-flavours found in freshwater fish?
Which factor is often linked to the off-flavours found in freshwater fish?
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What does geosmin contribute to in fish?
What does geosmin contribute to in fish?
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What type of bacteria predominantly dominate tropical fish caught in warm waters?
What type of bacteria predominantly dominate tropical fish caught in warm waters?
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What negative aspect does an oil spill have on the quality of fish?
What negative aspect does an oil spill have on the quality of fish?
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What was observed regarding the adaptation of tropical fish bacteria to chilled temperatures?
What was observed regarding the adaptation of tropical fish bacteria to chilled temperatures?
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Why might tropical fish have a slower growth of psychrotrophic bacteria compared to temperate fish?
Why might tropical fish have a slower growth of psychrotrophic bacteria compared to temperate fish?
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Which process explains the off-flavour of fish that occurs due to certain feeding habits?
Which process explains the off-flavour of fish that occurs due to certain feeding habits?
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What is indicated by the generation times of fish spoilage bacteria when pre-cultured at different temperatures?
What is indicated by the generation times of fish spoilage bacteria when pre-cultured at different temperatures?
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Which factor is pointed out as varying among different fish species contributing to shelf life differences?
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Study Notes
Fish Overview
- Defined as aquatic vertebrates using gills for oxygen and fins with fin rays.
- Major fish groups include cartilaginous fishes (sharks and rays) and bony fishes.
- Over 20,000 fish species exist, with 58% found in marine environments.
- Warm and temperate waters host around 8,000 species; only 225 species inhabit the open ocean.
Taxonomy of Fish
- Taxonomy classifies fish based on evolutionary relationships.
- Scientific names follow binomial nomenclature, comprising genus and species (e.g., Delphinus delphis for common dolphin).
- Common names can cause confusion due to regional variations.
Classification by Characteristics
- Fish are categorized into:
- Cyclostomes: jawless fish (lampreys, slime-eels).
- Chondrichthyes: cartilaginous fish (sharks, rays) with high urea content.
-
Teleostei: bony fish, further divided into:
- Pelagic fish (fatty: herring, mackerel).
- Demersal fish (lean: cod, haddock).
Anatomy and Physiology
Skeleton
- Fish possess a vertebral column (backbone) and cranium.
- Backbone is segmented into vertebrae with neural spines; ribs may vary from cartilaginous to bony.
Muscle Anatomy and Function
- Fish muscle lacks tendons, consists of parallel muscle cells (myotomes) connected by connective tissue (myocommata).
- Dorsal and ventral muscle parts differ in fiber lengths and diameters.
- Dark muscle, rich in lipids and myoglobin, is more prevalent in active pelagic species.
Muscle Contraction
- Contraction initiated by nervous impulses releasing Ca++, activating ATP-ase for muscle fiber contraction.
- Dark muscle has higher energy; utilizes aerobic metabolism, while light muscle relies on anaerobic metabolism.
Cardiovascular System
- Fish heart operates on a single circulation system with two chambers.
- Blood is pumped to gills for oxygenation, then distributed to the body.
- Fish blood volume is 1.5-3.0% of body weight; primarily in internal organs.
Bleeding and Handling
- Bleeding fish post-capture can enhance fillet quality.
- Recommendations vary on bleeding methods and times to limit discoloration and ensure quality.
- Rough handling can lead to bruising and contamination of muscle tissues.
Growth and Reproduction
- Fish growth involves increasing muscle cell size, not quantity.
- Sexual maturity is generally size-dependent, reaching earlier in males.
- Gonad development takes energy, often occurring during low food intake.
Chemical Composition
- Varies by species, age, sex, environment, and season.
- Key constituents include protein, lipid, and carbohydrate percentages, with fish typically lower in protein than isolated beef muscle.
Sensory Changes in Fish
- Sensory changes relate to appearance, odour, texture, and taste of fish, crucial for assessing freshness.
- Rigor mortis begins immediately post-mortem, characterized by muscle stiffening, lasting for a day or more before resolving.
- Fish muscle starts soft and limp post-death, then becomes hard and stiff due to rigor mortis, followed by a relaxed, non-elastic state.
- Onset and duration of rigor mortis vary by species and are influenced by temperature, handling, and fish condition.
- High temperatures accelerate rigor mortis, while some tropical fish show a faster onset at 0°C.
- Stress and glycogen depletion at death hasten rigor mortis onset, with stunning methods significantly affecting timing.
- Pre-rigor filleting yields better quality; rigor mortis leads to stiff muscle and poor filleting yields.
- Post-rigor, fish flesh becomes firm and elastic, while cooking pre-rigor results in a soft texture.
Evaluation of Freshness
- Sensory evaluations consider appearance, texture, and odour, influenced by storage conditions.
- Fish stored without ice spoil faster but have less visible change than those stored in ice.
- Freshness changes can be categorized into four distinct phases:
- Phase 1: Fresh fish has a sweet, delicate taste; optimal taste observed 2-3 days post-catch.
- Phase 2: Loss of characteristic taste and odour; flesh still pleasant.
- Phase 3: Signs of spoilage with unpleasant odours; texture deteriorates.
- Phase 4: Fish is spoiled, exhibiting putrid characteristics.
Autolytic Changes and Energy Production
- Autolysis denotes "self-digestion," distinguishing between bacterial and enzymatic spoilage.
- Lack of oxygen post-mortem disrupts normal energy production in muscles, relying on anaerobic pathways which are less efficient than aerobic respiration.
- Depletion of ATP during rigor mortis results in stiff, inextensible muscle, complicating processing.
- pH drops during post-mortem glycolysis, affecting muscle properties; drops range from 6.8 to lower levels depending on species.
- Stress affects glycogen levels pre-capture, consequently altering post-mortem pH and quality.
Autolysis and Nucleotide Catabolism
- Rigor mortis onset correlates with a drop in ATP levels and degradation of ATP to AMP, IMP, and further derivatives.
- Autolytic changes follow a predictable pattern after death, affecting perceived freshness quality.
- Changes in ATP and its catabolites indicate spoilage but do not directly correlate with texture changes.
- The freshness index (K value) is useful, but variability among species makes it unreliable for all marine fish.### Hx Determination and Fish Species
- Hx determination is unlikely to be useful for species like swordfish and redfish due to their specific biological characteristics.
Autolytic Changes in Fish
- Physical handling accelerates autolytic changes in chilled fish, affecting edibility and filleting yields.
- Sterile fillets show a greater breakdown rate of nucleotide catabolites compared to non-sterile cod, indicating that autolytic enzymes are compartmentalized.
Importance of Handling Practices
- Storing iced fish in boxes over 30 cm deep or allowing stacking can exacerbate autolysis.
- Systems for moving fish must protect delicate tissues from physical damage.
Nucleotide Catabolite Analysis
- Rapid methods exist for determining individual nucleotide catabolites and freshness indices.
Proteolytic Enzymes and Fish Quality
- Autolytic proteolysis in fish leads to tissue softening, most notably in pelagic species like herring, especially during summer feeding, impacting commercial value.
- Autolysis can promote bacterial growth, worsening spoilage and lowering fish quality.
Cathepsins in Fish Autolysis
- Cathepsins, acid proteases stored in lysosomes, become active post-mortem after physical stress, leading to significant tissue breakdown.
- Cathepsin L is a major factor in muscle softening, with its activity correlated to the texture of fish muscle.
Effects of Freezing on Autolysis
- Freezing breaks cell membranes, releasing enzymes like cathepsins, enhancing autolysis and softening.
- Studies show cathepsin L activity is higher in frozen/thawed tissues compared to fresh, influencing the muscle's texture.
Calpains Role in Texture Changes
- Calpains, calcium-activated proteases, significantly contribute to fish muscle autolysis, particularly at physiological pH levels.
- Active at lower temperatures compared to mammalian counterparts, calpains contribute to texture softening during chilled storage.
Collagenase Effects on Fish Texture
- Collagenases weaken connective tissue in fish, leading to gaping in fillets and softening during storage.
- The breakdown of type V collagen correlates with textural degradation of fish tissue.
TMAO and Formaldehyde Production
- TMAO, regulated by bacterial action and intrinsic enzymes, can be converted into dimethylamine and formaldehyde, leading to detrimental toughening of fish muscle.
- Enzymes responsible for this reaction, especially in gadoid fishes, become active upon tissue disruption by freezing.
Prevention Strategies for Autolytic Changes
- Minimizing physical damage and maintaining low storage temperatures (< -30°C) can prevent toughening from autolytic actions.
- Importance of adhering to proper handling practices before freezing to maintain fish quality.
General Summary of Autolytic Changes in Fish
- Both physical disruption and environmental conditions play critical roles in the rate and extent of autolytic changes in fish.
- Key enzymes involved include glycolytic enzymes, autolytic enzymes for nucleotide breakdown, cathepsins, calpains, and collagenases, each with specific impacts on texture and quality.
Sensory Changes in Fish
- Sensory changes relate to appearance, odour, texture, and taste of fish, crucial for assessing freshness.
- Rigor mortis begins immediately post-mortem, characterized by muscle stiffening, lasting for a day or more before resolving.
- Fish muscle starts soft and limp post-death, then becomes hard and stiff due to rigor mortis, followed by a relaxed, non-elastic state.
- Onset and duration of rigor mortis vary by species and are influenced by temperature, handling, and fish condition.
- High temperatures accelerate rigor mortis, while some tropical fish show a faster onset at 0°C.
- Stress and glycogen depletion at death hasten rigor mortis onset, with stunning methods significantly affecting timing.
- Pre-rigor filleting yields better quality; rigor mortis leads to stiff muscle and poor filleting yields.
- Post-rigor, fish flesh becomes firm and elastic, while cooking pre-rigor results in a soft texture.
Evaluation of Freshness
- Sensory evaluations consider appearance, texture, and odour, influenced by storage conditions.
- Fish stored without ice spoil faster but have less visible change than those stored in ice.
- Freshness changes can be categorized into four distinct phases:
- Phase 1: Fresh fish has a sweet, delicate taste; optimal taste observed 2-3 days post-catch.
- Phase 2: Loss of characteristic taste and odour; flesh still pleasant.
- Phase 3: Signs of spoilage with unpleasant odours; texture deteriorates.
- Phase 4: Fish is spoiled, exhibiting putrid characteristics.
Autolytic Changes and Energy Production
- Autolysis denotes "self-digestion," distinguishing between bacterial and enzymatic spoilage.
- Lack of oxygen post-mortem disrupts normal energy production in muscles, relying on anaerobic pathways which are less efficient than aerobic respiration.
- Depletion of ATP during rigor mortis results in stiff, inextensible muscle, complicating processing.
- pH drops during post-mortem glycolysis, affecting muscle properties; drops range from 6.8 to lower levels depending on species.
- Stress affects glycogen levels pre-capture, consequently altering post-mortem pH and quality.
Autolysis and Nucleotide Catabolism
- Rigor mortis onset correlates with a drop in ATP levels and degradation of ATP to AMP, IMP, and further derivatives.
- Autolytic changes follow a predictable pattern after death, affecting perceived freshness quality.
- Changes in ATP and its catabolites indicate spoilage but do not directly correlate with texture changes.
- The freshness index (K value) is useful, but variability among species makes it unreliable for all marine fish.### Hx Determination and Fish Species
- Hx determination is unlikely to be useful for species like swordfish and redfish due to their specific biological characteristics.
Autolytic Changes in Fish
- Physical handling accelerates autolytic changes in chilled fish, affecting edibility and filleting yields.
- Sterile fillets show a greater breakdown rate of nucleotide catabolites compared to non-sterile cod, indicating that autolytic enzymes are compartmentalized.
Importance of Handling Practices
- Storing iced fish in boxes over 30 cm deep or allowing stacking can exacerbate autolysis.
- Systems for moving fish must protect delicate tissues from physical damage.
Nucleotide Catabolite Analysis
- Rapid methods exist for determining individual nucleotide catabolites and freshness indices.
Proteolytic Enzymes and Fish Quality
- Autolytic proteolysis in fish leads to tissue softening, most notably in pelagic species like herring, especially during summer feeding, impacting commercial value.
- Autolysis can promote bacterial growth, worsening spoilage and lowering fish quality.
Cathepsins in Fish Autolysis
- Cathepsins, acid proteases stored in lysosomes, become active post-mortem after physical stress, leading to significant tissue breakdown.
- Cathepsin L is a major factor in muscle softening, with its activity correlated to the texture of fish muscle.
Effects of Freezing on Autolysis
- Freezing breaks cell membranes, releasing enzymes like cathepsins, enhancing autolysis and softening.
- Studies show cathepsin L activity is higher in frozen/thawed tissues compared to fresh, influencing the muscle's texture.
Calpains Role in Texture Changes
- Calpains, calcium-activated proteases, significantly contribute to fish muscle autolysis, particularly at physiological pH levels.
- Active at lower temperatures compared to mammalian counterparts, calpains contribute to texture softening during chilled storage.
Collagenase Effects on Fish Texture
- Collagenases weaken connective tissue in fish, leading to gaping in fillets and softening during storage.
- The breakdown of type V collagen correlates with textural degradation of fish tissue.
TMAO and Formaldehyde Production
- TMAO, regulated by bacterial action and intrinsic enzymes, can be converted into dimethylamine and formaldehyde, leading to detrimental toughening of fish muscle.
- Enzymes responsible for this reaction, especially in gadoid fishes, become active upon tissue disruption by freezing.
Prevention Strategies for Autolytic Changes
- Minimizing physical damage and maintaining low storage temperatures (< -30°C) can prevent toughening from autolytic actions.
- Importance of adhering to proper handling practices before freezing to maintain fish quality.
General Summary of Autolytic Changes in Fish
- Both physical disruption and environmental conditions play critical roles in the rate and extent of autolytic changes in fish.
- Key enzymes involved include glycolytic enzymes, autolytic enzymes for nucleotide breakdown, cathepsins, calpains, and collagenases, each with specific impacts on texture and quality.
Effect of Storage Temperature
- Microbial vs. Enzymatic Activity: Temperature between 0-25°C significantly impacts microbial growth more than enzymatic activity; many bacteria, including Shewanella putrefaciens, grow poorly below 10°C, with growth rates drastically reduced at 0°C.
- Extended Shelf Life: Low storage temperatures extend the shelf life of fresh fish products due to reduced microbial spoilage.
- Relative Rate of Spoilage (RRS): RRS is a crucial measure expressed for various seafood stored at different temperatures, showing drastic differences in shelf life at 0°C, 5°C, and 10°C. For example, crab has a shelf life of 10.1 days at 0°C but only 2.6 days at 10°C.
- Spoilage Models: The relationship between temperature and RRS is represented by an S-shaped spoilage curve, confirming earlier research findings and allowing predictions of spoilage based on temperature changes.
- Temperature Influence on Reactions: While the Arrhenius Equation describes temperature effects on chemical reactions, it isn't completely accurate for microbial growth over various temperatures.
- Psychrotrophic Bacteria: Preferred survival temperatures for psychrotrophic bacteria yield a theoretical minimum growth temperature (Tmin), around -10°C for some species, underscoring the effectiveness of optimized storage models.
Superchilling and Partial Freezing
- Superchilling Defined: Storing fish at temperatures from 0°C to -4°C is termed superchilling, which significantly prolongs shelf life compared to regular icing (e.g., shelf life at -3°C can exceed that at 0°C).
- Frigido-system Technology: Developed in the 1960s, this technology maintains sub-zero temperatures in fish holds, reducing fish:ice ratios and enhancing chilling efficacy.
- Negative Effects on Freshness: Some fish may lose quality due to superchilling, with increased drip loss and inferior texture characteristics compared to ice storage, highlighting species variability in response to superchilling.
- Liquid Refrigerated Sea Water (RSW): RSW reduces oxygen exposure and facilitates quicker chilling compared to traditional ice methods, although it may impart a salty taste to some fish species.
Importance of Hygiene During Handling
- Onboard Hygienic Practices: Research indicates that while proper hygiene during fish handling can reduce bacterial contamination, strict measures are less critical compared to rapid chilling methods.
- Bacterial Growth Factors: Initial bacterial levels influence storage life more significantly in the latter stages, with high contamination leading to reduced shelf life post the first week.
- Handling Logistics: Fish storage boxes should permit melt-water drainage to enhance chilling efficiency without significantly increasing contamination risks.
Microbial Control Methods
- Limitations of Traditional Methods: Techniques like irradiation or antibiotics for bacterial control are often rejected due to cost or health concerns.
- Effective Alternatives: CO2 treatment and chlorinated water washing are promising methods for bacterial reduction, improving overall product quality during handling and distribution.
Conclusion and Future Implications
- Superchilling as a Viable Option: While superchilling can improve shelf life significantly, the potential drawbacks for some species necessitate targeted application.
- Technological Advances: Continued development of predictive models and monitoring technologies such as temperature loggers will enhance seafood quality control, ensuring safer consumption practices.### Handling and Storage of Fish
- Chlorine can prolong storage life but creates off-flavors in fish.
- Newly caught fish should be washed in clean seawater to remove visible blood and dirt, with no significant impact on bacterial count or storage life.
Impact of Anaerobic Conditions and Carbon Dioxide (CO2)
- High CO2 concentrations inhibit microbial growth, thereby extending shelf life where spoilage is microbially driven.
- Technologies like vacuum packaging (VP) and modified atmosphere packaging (MAP) are effective, particularly for meats, but provide minimal shelf life extension for fish.
Shelf Life Comparison
- Shelf life (in weeks) at 0.0 - 4.0°C:
- Lean fish:
- Air: 1-2,
- VP: 1-2,
- MAP: 1-3
- Fatty fish:
- Air: 1-2,
- VP: 1-2,
- MAP: 1-3
- Lean fish:
- Meat products show significantly longer shelf lives under similar conditions compared to fish products.
Microbial Spoilage
- Aerobic spoilage in meats is caused primarily by Pseudomonas spp., which are inhibited in anaerobic conditions, shifting spoilage to Gram-positive lactic acid bacteria.
- Fish spoil primarily from Shewanella putrefaciens under aerobic conditions, countered by high CO2 levels in packaged fish.
- Photobacterium phosphoreum, a Gram-negative organism, is identified as the primary spoilage microorganism in vacuum-packaged cod, growing well under anaerobic conditions.
Non-Microbial Spoilage Reactions
- Increased CO2 causes pH decrease (0.2-0.3 units), affecting muscle protein water-holding capacity, leading to higher drip loss in some fish.
- Sensory quality of fish in high CO2 environments may be compromised, particularly at 100% CO2, while up to 60% CO2 shows minimal texture impact on cod.
Refrigerated Seawater (RSW) Systems
- RSW + CO2 improves the shelf life of certain fish products, compared to ice storage.
- CO2 can prolong the shelf life of pink shrimp significantly, but may adversely affect color and texture in other species like mackerel.
Factors Affecting Quality and Storage Life
- Evisceration generally enhances quality and shelf life, particularly in lean species like cod, where ungutted fish show rapid quality degradation.
- Gutting increases exposure to air, raising oxidation risks, leading to discoloration.
Species-Specific Insights
- Fatty fish like herring and sardines are often stored ungutted due to challenges with discoloration and rancidity.
- Quality of perishable fish species is affected by species, fishing grounds, fishing methods, and seasonal factors.
Intrinsic Factors of Spoilage
- Spoilage is slower in larger fish, flat fish tend to keep better, and lean fish have longer storage capabilities than fatty species.
- Factors such as rough handling lead to increased spoilage rates due to physical damage increasing bacterial access.
Bacterial Growth and Spoilage Rate
- Post-mortem pH and fat content directly influence spoilage rates; higher pH and fat content generally lead to faster spoilage.
- Bacterial growth rates differ among species, impacting overall shelf life.
Environmental and Temperature Influences
- Cold-water species generally exhibit shorter iced shelf lives than tropical species, which have been reported to outperform in storage longevity.
- Historical studies have shown some tropical fish maintain freshness in ice for 20-30 days, indicating a significant difference in spoilage dynamics between warm and cold-water species.### Fish Shelf Life Comparison
- Fish from warm waters generally have longer shelf lives compared to those from temperate waters.
- Freshwater fish species exhibit longer shelf lives than marine species.
- Tropical marine fish can last 12-35 days when stored in ice, whereas temperate marine fish last 2-21 days.
- Temperate freshwater fish shelf life ranges from 9 to 20 days.
Factors Affecting Fish Spoilage
- Prolonged shelf life in tropical fish may be related to lower levels of Trimethylamine (TMA) and Total Volatile Nitrogen (TVN) during storage.
- Pseudomonas spp. are often responsible for spoilage in tropical fish, differing from Shewanella spp. which produce TMA and sulfides.
- The absence of TMA and TVN in some tropical fish suggests spoilage mechanisms that might not involve typical bacteria.
- Tropical fish exhibit a lag phase of 1-2 weeks before bacterial growth resumes when stored in ice.
Bacterial Flora Influences
- Gram-negative bacteria such as Pseudomonas and Acinetobacter are prevalent in tropical fish, potentially influencing spoilage rates.
- Studies show high percentages (40-90%) of tropical fish bacteria can grow at chill temperatures (7°C).
- Tropical fish tend to have slower spoilage rates compared to temperate fish, supporting the adaptation hypothesis.
Physiological Differences
- pH levels of tropical fish measured between 6-7, lower than some temperate species, may contribute to longer shelf life.
- The thick skin of tropical fish might also play a role in preservation, though further research on skin properties is needed.
Off-Flavours in Fish
- Off-flavours in fish can arise from diet, leading to taints such as "mineral oil" from planktonic molluscs.
- Bitter tastes in herring can be due to larvae from Mytilus spp., while muddy-earthy taints in freshwater fish stem from geosmin and 2-methylisoborneol.
- Iodine-like flavours may indicate the presence of volatile bromophenolic compounds derived from marine organisms.
- Environmental factors, such as oil spills, can cause oil taint due to soluble hydrocarbon compounds that accumulate in fish flesh.
Storage and Handling Practices
- Proper handling, such as rapid chilling of ungutted fish, is crucial for maintaining quality.
- The type of bacterial flora and environmental conditions before and after catch impact fish longevity and quality.
Effect of Storage Temperature
- Microbial vs. Enzymatic Activity: Temperature between 0-25°C significantly impacts microbial growth more than enzymatic activity; many bacteria, including Shewanella putrefaciens, grow poorly below 10°C, with growth rates drastically reduced at 0°C.
- Extended Shelf Life: Low storage temperatures extend the shelf life of fresh fish products due to reduced microbial spoilage.
- Relative Rate of Spoilage (RRS): RRS is a crucial measure expressed for various seafood stored at different temperatures, showing drastic differences in shelf life at 0°C, 5°C, and 10°C. For example, crab has a shelf life of 10.1 days at 0°C but only 2.6 days at 10°C.
- Spoilage Models: The relationship between temperature and RRS is represented by an S-shaped spoilage curve, confirming earlier research findings and allowing predictions of spoilage based on temperature changes.
- Temperature Influence on Reactions: While the Arrhenius Equation describes temperature effects on chemical reactions, it isn't completely accurate for microbial growth over various temperatures.
- Psychrotrophic Bacteria: Preferred survival temperatures for psychrotrophic bacteria yield a theoretical minimum growth temperature (Tmin), around -10°C for some species, underscoring the effectiveness of optimized storage models.
Superchilling and Partial Freezing
- Superchilling Defined: Storing fish at temperatures from 0°C to -4°C is termed superchilling, which significantly prolongs shelf life compared to regular icing (e.g., shelf life at -3°C can exceed that at 0°C).
- Frigido-system Technology: Developed in the 1960s, this technology maintains sub-zero temperatures in fish holds, reducing fish:ice ratios and enhancing chilling efficacy.
- Negative Effects on Freshness: Some fish may lose quality due to superchilling, with increased drip loss and inferior texture characteristics compared to ice storage, highlighting species variability in response to superchilling.
- Liquid Refrigerated Sea Water (RSW): RSW reduces oxygen exposure and facilitates quicker chilling compared to traditional ice methods, although it may impart a salty taste to some fish species.
Importance of Hygiene During Handling
- Onboard Hygienic Practices: Research indicates that while proper hygiene during fish handling can reduce bacterial contamination, strict measures are less critical compared to rapid chilling methods.
- Bacterial Growth Factors: Initial bacterial levels influence storage life more significantly in the latter stages, with high contamination leading to reduced shelf life post the first week.
- Handling Logistics: Fish storage boxes should permit melt-water drainage to enhance chilling efficiency without significantly increasing contamination risks.
Microbial Control Methods
- Limitations of Traditional Methods: Techniques like irradiation or antibiotics for bacterial control are often rejected due to cost or health concerns.
- Effective Alternatives: CO2 treatment and chlorinated water washing are promising methods for bacterial reduction, improving overall product quality during handling and distribution.
Conclusion and Future Implications
- Superchilling as a Viable Option: While superchilling can improve shelf life significantly, the potential drawbacks for some species necessitate targeted application.
- Technological Advances: Continued development of predictive models and monitoring technologies such as temperature loggers will enhance seafood quality control, ensuring safer consumption practices.### Handling and Storage of Fish
- Chlorine can prolong storage life but creates off-flavors in fish.
- Newly caught fish should be washed in clean seawater to remove visible blood and dirt, with no significant impact on bacterial count or storage life.
Impact of Anaerobic Conditions and Carbon Dioxide (CO2)
- High CO2 concentrations inhibit microbial growth, thereby extending shelf life where spoilage is microbially driven.
- Technologies like vacuum packaging (VP) and modified atmosphere packaging (MAP) are effective, particularly for meats, but provide minimal shelf life extension for fish.
Shelf Life Comparison
- Shelf life (in weeks) at 0.0 - 4.0°C:
- Lean fish:
- Air: 1-2,
- VP: 1-2,
- MAP: 1-3
- Fatty fish:
- Air: 1-2,
- VP: 1-2,
- MAP: 1-3
- Lean fish:
- Meat products show significantly longer shelf lives under similar conditions compared to fish products.
Microbial Spoilage
- Aerobic spoilage in meats is caused primarily by Pseudomonas spp., which are inhibited in anaerobic conditions, shifting spoilage to Gram-positive lactic acid bacteria.
- Fish spoil primarily from Shewanella putrefaciens under aerobic conditions, countered by high CO2 levels in packaged fish.
- Photobacterium phosphoreum, a Gram-negative organism, is identified as the primary spoilage microorganism in vacuum-packaged cod, growing well under anaerobic conditions.
Non-Microbial Spoilage Reactions
- Increased CO2 causes pH decrease (0.2-0.3 units), affecting muscle protein water-holding capacity, leading to higher drip loss in some fish.
- Sensory quality of fish in high CO2 environments may be compromised, particularly at 100% CO2, while up to 60% CO2 shows minimal texture impact on cod.
Refrigerated Seawater (RSW) Systems
- RSW + CO2 improves the shelf life of certain fish products, compared to ice storage.
- CO2 can prolong the shelf life of pink shrimp significantly, but may adversely affect color and texture in other species like mackerel.
Factors Affecting Quality and Storage Life
- Evisceration generally enhances quality and shelf life, particularly in lean species like cod, where ungutted fish show rapid quality degradation.
- Gutting increases exposure to air, raising oxidation risks, leading to discoloration.
Species-Specific Insights
- Fatty fish like herring and sardines are often stored ungutted due to challenges with discoloration and rancidity.
- Quality of perishable fish species is affected by species, fishing grounds, fishing methods, and seasonal factors.
Intrinsic Factors of Spoilage
- Spoilage is slower in larger fish, flat fish tend to keep better, and lean fish have longer storage capabilities than fatty species.
- Factors such as rough handling lead to increased spoilage rates due to physical damage increasing bacterial access.
Bacterial Growth and Spoilage Rate
- Post-mortem pH and fat content directly influence spoilage rates; higher pH and fat content generally lead to faster spoilage.
- Bacterial growth rates differ among species, impacting overall shelf life.
Environmental and Temperature Influences
- Cold-water species generally exhibit shorter iced shelf lives than tropical species, which have been reported to outperform in storage longevity.
- Historical studies have shown some tropical fish maintain freshness in ice for 20-30 days, indicating a significant difference in spoilage dynamics between warm and cold-water species.### Fish Shelf Life Comparison
- Fish from warm waters generally have longer shelf lives compared to those from temperate waters.
- Freshwater fish species exhibit longer shelf lives than marine species.
- Tropical marine fish can last 12-35 days when stored in ice, whereas temperate marine fish last 2-21 days.
- Temperate freshwater fish shelf life ranges from 9 to 20 days.
Factors Affecting Fish Spoilage
- Prolonged shelf life in tropical fish may be related to lower levels of Trimethylamine (TMA) and Total Volatile Nitrogen (TVN) during storage.
- Pseudomonas spp. are often responsible for spoilage in tropical fish, differing from Shewanella spp. which produce TMA and sulfides.
- The absence of TMA and TVN in some tropical fish suggests spoilage mechanisms that might not involve typical bacteria.
- Tropical fish exhibit a lag phase of 1-2 weeks before bacterial growth resumes when stored in ice.
Bacterial Flora Influences
- Gram-negative bacteria such as Pseudomonas and Acinetobacter are prevalent in tropical fish, potentially influencing spoilage rates.
- Studies show high percentages (40-90%) of tropical fish bacteria can grow at chill temperatures (7°C).
- Tropical fish tend to have slower spoilage rates compared to temperate fish, supporting the adaptation hypothesis.
Physiological Differences
- pH levels of tropical fish measured between 6-7, lower than some temperate species, may contribute to longer shelf life.
- The thick skin of tropical fish might also play a role in preservation, though further research on skin properties is needed.
Off-Flavours in Fish
- Off-flavours in fish can arise from diet, leading to taints such as "mineral oil" from planktonic molluscs.
- Bitter tastes in herring can be due to larvae from Mytilus spp., while muddy-earthy taints in freshwater fish stem from geosmin and 2-methylisoborneol.
- Iodine-like flavours may indicate the presence of volatile bromophenolic compounds derived from marine organisms.
- Environmental factors, such as oil spills, can cause oil taint due to soluble hydrocarbon compounds that accumulate in fish flesh.
Storage and Handling Practices
- Proper handling, such as rapid chilling of ungutted fish, is crucial for maintaining quality.
- The type of bacterial flora and environmental conditions before and after catch impact fish longevity and quality.
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Description
Explore the fascinating world of fish, from their anatomy and physiology to their classification and taxonomy. This quiz covers various groups, habitats, and characteristics that define fish as aquatic vertebrates. Test your knowledge on the diversity of over 20,000 species and their evolutionary relationships.
