Fisheries and Seafood Processing

Fish and Fish Products

• Fish are a valuable component of the human diet, providing essential amino acids, highly unsaturated fatty acids, vitamin-A-rich oils, and micronutrients.
• The global marine fish capture has remained between 78 to 84 million tons of live weight from 1990 to 2020, with no signs of increased capture.
• Sustainability issues may arise in natural fisheries, and fish production may need to expand into more inland waters or scientifically increase marine fish production.
• China and India play a major role in increasing inland fisheries, with some African countries joining in the production.

Post-Harvest Losses and Waste

• Post-harvest loss of fish due to quality and safety problems is around 35%, with a range of 20–75%.
• Reducing these losses is one approach to ensure that the global food-fish demand can be met.
• About 40% of the total harvest is lost as non-edible components.

Fish Waste and Utilization

• Fish waste, accounting for up to 50% of the losses, could be converted into novel products through value addition.
• The processing of fish waste carries a high potential for meeting the increasing food demands and attaining profits in the fish industry.
• Waste utilization is an important step in sustainable circular economies, a need identified in the current goals of the United Nations’ policies.

Safety of Fish and Fishery Products

• Fish become unsafe for human consumption due to natural and man-made activities, including microbial or chemical contaminants.
• Autolysis of fish components, such as glycogen, proteins, and peptides, can lead to unappealing constituents and properties.
• Microbial food safety hazards, including pathogenic microorganisms, can grow in fish, rendering them unsafe as food.

Microbial Food Safety Hazards

• Pathogenic microorganisms are present in the marine environment, and their growth can be enhanced by symbiosis among spoilage bacteria.
• Pre-harvest and post-harvest microorganisms, including Vibrio parahaemolyticus and Vibrio cholerae, can contaminate fish and shellfish.
• Contamination by pathogenic microorganisms tends to be more local, triggered by coastal contaminations.

Biotoxins and Harmful Algal Blooms

• Biotoxins from algal blooms in the oceans can contaminate fish, posing food safety hazards.
• The FAO has observed the increasing appearance of hazardous biotoxins from tropical regions, predominantly from the upwelling regions of the Indian Ocean.
• Avoiding fishing in infected marine locations is currently practiced in temperate regions to prevent the exposure of humans to biotoxins.### Microbial Food Safety Hazards
• Aeromonas, producing enterotoxins and hemolysins, are associated with locations of seawater mixing with river waters.
• Aeromonas sp. are of a low food-safety risk.
• Microbial pathogens of pre-harvest origin in fish can also appear as post-harvest pathogens, since they are carried with the harvest into the markets.
• Common post-harvest pathogens affecting fish include:
  • Escherichia coli
  • Salmonella species
  • Staphylococcus aureus
  • Clostridium botulinum
  • Listeria monocytogenes
  • Shigella species
  • Bacillus cereus
  • Campylobacter jejuni
  • Yersinia enterocolitica
  • Histamine producers
• E. coli, being a common bacterium of fecal origin, tends to be present more often with poorly handled fish.
• Salmonella species and Staphylococcus aureus, originating from human contact at handling, are found more frequently than other pathogens in market food fish.
• Spoilage of fish and food safety hazards originating from post-harvest microbiological contaminations have been reviewed.

Chemical Food Safety Hazards

• Chemical pollutants tend to accumulate continuously in marine and inland waters and enter fish muscles, reaching concentrations hazardous to humans.
• Common chemical and physical contaminants affecting the safety of food fish include:
  • Agrichemical residues
  • Animal drug residues
  • Animal excreta containing toxic chemical residues
  • Organochlorine (OC) pesticide residues
  • Polycyclic aromatic hydrocarbons (PAHs)
  • Toxic metal residues (arsenic, mercury, cadmium, lead)
• Organochlorine (OC) pesticide residues in water are absorbed more through the gills than through the stomach, being deposited in fish muscles.
• Toxic metals enter the fish chain continuously, starting from sea plants through benthic fish to pelagic fish.
• Mercury is converted to the neurotoxic methyl mercury by marine flora, increasing the food safety hazards through food fish.
• The ability of sword fish and tuna fish to accumulate toxicologically high concentrations of mercury and cadmium are indicated by the high enrichment factors for them.

Plastic Pollution

• Nurdles and plastics of differing origin are released continuously into waterways.
• Plastics account for 80% of marine litter.
• Plastics themselves release carcinogens such as phthalates, bisphenol A, flame retardants, organophosphates, perfluorinated chemicals, and organo-tin compounds into the fish gut when swallowed.
• The bioaccumulation of toxins transferred through nurdles may create food safety hazards to humans through food fish.

Processing and Preservation of Fish and Fish Products

• Raw fish need to be treated to make them appealing as food.

• Harvested fish are pre-processed to get rid of adhering non-edible components and physical contaminants.

• Fish are processed to retain the organoleptic characteristics of muscles by freezing, heating, controlling the water activity by removing moisture, using additives, or by irradiation.

• Processing aims to generate modified products from fresh fish that have consumer appeal.

• The value addition associated with processing brings increased profits and sustainability to the fish industry.

• Preserving fish to increase their shelf life and to prevent changes in their natural characteristics is important for consumer appeal.

• Conventional fish processing and preservation methods include:

  • Drying with salt
  • Air drying
  • Storing in ice
  • Smoking
  • Fermentation### Conventional Fish Preservation Methods

• In temperate countries, fish are preserved by suspending them in air and exposing them to low humidity at subzero temperatures for weeks to reduce water activity and control microbial growth.

• In tropical countries, heat from solar radiation is applied to evaporate moisture, but prolonged sun drying can lead to microbial spoilage.

• Techniques like air drying, salt drying, smoke curing, and fermenting are used to preserve fish, each with its own effects on quality and safety.

Effects of Conventional Methods on Quality and Safety

• Air drying minimizes microbial growth and devitalizes Anisakid parasites, but it can lead to a 12-month shelf life.
• Salt drying increases free fatty acids and partial loss of nutritional quality, and it's amenable to mold attacks at low salt concentrations.
• Smoke curing deposits low-molecular-weight acids, aldehydes, and phenolics, but it also deposits carcinogenic polycyclic aromatic hydrocarbons on the surface.
• Fermenting uses undersized and low-value fish, producing alkaline conditions, and delivering soft-solid textured fish pastes, but it can lead to biogenic amine formation, which impairs food safety.

Limitations and Concerns

• Conventional methods reduce the nutritional quality of fish through changes in proteins, carbohydrates, and lipids due to heat and salt.
• Pathogenic microorganisms are controlled satisfactorily, but halophilic bacteria and fungi may be active in salted dried fish unless optimal salt concentrations are maintained.
• Combining conventional fish drying methods with other controls, botanicals, and chemicals remains a possibility for ensuring product safety from microbial contaminants and mycotoxins.

Emerging Food Processing and Preservation Technologies

• Consumer demand is for fresh fish, seeking fish that have undergone the fewest interactions and no thermal treatments.
• Emerging technologies include irradiation and canning of fish to increase their shelf life, but canned fish is cooked, changing the sensory appeal.

Effects of Emerging Technologies on Quality and Safety

• High-pressure processing (HPP) retains sensory and nutritional quality, inactivates microorganisms and spoilage enzymes.
• Ultrasound technology retains sensory and nutritional quality, inactivates microorganisms and enzymes.
• Pulsed electric field (PEF) affects cell permeability, inactivates microorganisms, but has limitations such as lipid oxidation and high cost.
• Cold plasma (CP) oxidizes cell membranes of microorganisms, but oxidation of lipids and proteins in fish muscles limits the application.
• Low-voltage variable-frequency electrostatic field and chemical preservatives (LVVFEF) combines the action of two methods, inactivates spoilage bacteria, and interferes with biochemical reactions.
• Pulsed light prevents the replication of DNA, resulting in cell death, and causes surface sterilization of fillets.
• Photodynamic inactivation attacks proteins, lipids, and nucleic acids in microorganisms, inactivating them, but microorganisms may generate tolerance, and photosensitizers may continue to be active in foods entering the human body.

Fish and Fish Products

• Fish are a valuable component of the human diet, providing essential amino acids, highly unsaturated fatty acids, vitamin-A-rich oils, and micronutrients.
• The global marine fish capture has remained between 78 to 84 million tons of live weight from 1990 to 2020, with no signs of increased capture.
• Sustainability issues may arise in natural fisheries, and fish production may need to expand into more inland waters or scientifically increase marine fish production.
• China and India play a major role in increasing inland fisheries, with some African countries joining in the production.

Post-Harvest Losses and Waste

• Post-harvest loss of fish due to quality and safety problems is around 35%, with a range of 20–75%.
• Reducing these losses is one approach to ensure that the global food-fish demand can be met.
• About 40% of the total harvest is lost as non-edible components.

Fish Waste and Utilization

• Fish waste, accounting for up to 50% of the losses, could be converted into novel products through value addition.
• The processing of fish waste carries a high potential for meeting the increasing food demands and attaining profits in the fish industry.
• Waste utilization is an important step in sustainable circular economies, a need identified in the current goals of the United Nations’ policies.

Safety of Fish and Fishery Products

• Fish become unsafe for human consumption due to natural and man-made activities, including microbial or chemical contaminants.
• Autolysis of fish components, such as glycogen, proteins, and peptides, can lead to unappealing constituents and properties.
• Microbial food safety hazards, including pathogenic microorganisms, can grow in fish, rendering them unsafe as food.

Microbial Food Safety Hazards

• Pathogenic microorganisms are present in the marine environment, and their growth can be enhanced by symbiosis among spoilage bacteria.
• Pre-harvest and post-harvest microorganisms, including Vibrio parahaemolyticus and Vibrio cholerae, can contaminate fish and shellfish.
• Contamination by pathogenic microorganisms tends to be more local, triggered by coastal contaminations.

Biotoxins and Harmful Algal Blooms

• Biotoxins from algal blooms in the oceans can contaminate fish, posing food safety hazards.
• The FAO has observed the increasing appearance of hazardous biotoxins from tropical regions, predominantly from the upwelling regions of the Indian Ocean.
• Avoiding fishing in infected marine locations is currently practiced in temperate regions to prevent the exposure of humans to biotoxins.### Microbial Food Safety Hazards
• Aeromonas, producing enterotoxins and hemolysins, are associated with locations of seawater mixing with river waters.
• Aeromonas sp. are of a low food-safety risk.
• Microbial pathogens of pre-harvest origin in fish can also appear as post-harvest pathogens, since they are carried with the harvest into the markets.
• Common post-harvest pathogens affecting fish include:
  • Escherichia coli
  • Salmonella species
  • Staphylococcus aureus
  • Clostridium botulinum
  • Listeria monocytogenes
  • Shigella species
  • Bacillus cereus
  • Campylobacter jejuni
  • Yersinia enterocolitica
  • Histamine producers
• E. coli, being a common bacterium of fecal origin, tends to be present more often with poorly handled fish.
• Salmonella species and Staphylococcus aureus, originating from human contact at handling, are found more frequently than other pathogens in market food fish.
• Spoilage of fish and food safety hazards originating from post-harvest microbiological contaminations have been reviewed.

Chemical Food Safety Hazards

• Chemical pollutants tend to accumulate continuously in marine and inland waters and enter fish muscles, reaching concentrations hazardous to humans.
• Common chemical and physical contaminants affecting the safety of food fish include:
  • Agrichemical residues
  • Animal drug residues
  • Animal excreta containing toxic chemical residues
  • Organochlorine (OC) pesticide residues
  • Polycyclic aromatic hydrocarbons (PAHs)
  • Toxic metal residues (arsenic, mercury, cadmium, lead)
• Organochlorine (OC) pesticide residues in water are absorbed more through the gills than through the stomach, being deposited in fish muscles.
• Toxic metals enter the fish chain continuously, starting from sea plants through benthic fish to pelagic fish.
• Mercury is converted to the neurotoxic methyl mercury by marine flora, increasing the food safety hazards through food fish.
• The ability of sword fish and tuna fish to accumulate toxicologically high concentrations of mercury and cadmium are indicated by the high enrichment factors for them.

Plastic Pollution

• Nurdles and plastics of differing origin are released continuously into waterways.
• Plastics account for 80% of marine litter.
• Plastics themselves release carcinogens such as phthalates, bisphenol A, flame retardants, organophosphates, perfluorinated chemicals, and organo-tin compounds into the fish gut when swallowed.
• The bioaccumulation of toxins transferred through nurdles may create food safety hazards to humans through food fish.

Processing and Preservation of Fish and Fish Products

• Raw fish need to be treated to make them appealing as food.

• Harvested fish are pre-processed to get rid of adhering non-edible components and physical contaminants.

• Fish are processed to retain the organoleptic characteristics of muscles by freezing, heating, controlling the water activity by removing moisture, using additives, or by irradiation.

• Processing aims to generate modified products from fresh fish that have consumer appeal.

• The value addition associated with processing brings increased profits and sustainability to the fish industry.

• Preserving fish to increase their shelf life and to prevent changes in their natural characteristics is important for consumer appeal.

• Conventional fish processing and preservation methods include:

  • Drying with salt
  • Air drying
  • Storing in ice
  • Smoking
  • Fermentation### Conventional Fish Preservation Methods

• In temperate countries, fish are preserved by suspending them in air and exposing them to low humidity at subzero temperatures for weeks to reduce water activity and control microbial growth.

• In tropical countries, heat from solar radiation is applied to evaporate moisture, but prolonged sun drying can lead to microbial spoilage.

• Techniques like air drying, salt drying, smoke curing, and fermenting are used to preserve fish, each with its own effects on quality and safety.

Effects of Conventional Methods on Quality and Safety

• Air drying minimizes microbial growth and devitalizes Anisakid parasites, but it can lead to a 12-month shelf life.
• Salt drying increases free fatty acids and partial loss of nutritional quality, and it's amenable to mold attacks at low salt concentrations.
• Smoke curing deposits low-molecular-weight acids, aldehydes, and phenolics, but it also deposits carcinogenic polycyclic aromatic hydrocarbons on the surface.
• Fermenting uses undersized and low-value fish, producing alkaline conditions, and delivering soft-solid textured fish pastes, but it can lead to biogenic amine formation, which impairs food safety.

Limitations and Concerns

• Conventional methods reduce the nutritional quality of fish through changes in proteins, carbohydrates, and lipids due to heat and salt.
• Pathogenic microorganisms are controlled satisfactorily, but halophilic bacteria and fungi may be active in salted dried fish unless optimal salt concentrations are maintained.
• Combining conventional fish drying methods with other controls, botanicals, and chemicals remains a possibility for ensuring product safety from microbial contaminants and mycotoxins.

Emerging Food Processing and Preservation Technologies

• Consumer demand is for fresh fish, seeking fish that have undergone the fewest interactions and no thermal treatments.
• Emerging technologies include irradiation and canning of fish to increase their shelf life, but canned fish is cooked, changing the sensory appeal.

Effects of Emerging Technologies on Quality and Safety

• High-pressure processing (HPP) retains sensory and nutritional quality, inactivates microorganisms and spoilage enzymes.
• Ultrasound technology retains sensory and nutritional quality, inactivates microorganisms and enzymes.
• Pulsed electric field (PEF) affects cell permeability, inactivates microorganisms, but has limitations such as lipid oxidation and high cost.
• Cold plasma (CP) oxidizes cell membranes of microorganisms, but oxidation of lipids and proteins in fish muscles limits the application.
• Low-voltage variable-frequency electrostatic field and chemical preservatives (LVVFEF) combines the action of two methods, inactivates spoilage bacteria, and interferes with biochemical reactions.
• Pulsed light prevents the replication of DNA, resulting in cell death, and causes surface sterilization of fillets.
• Photodynamic inactivation attacks proteins, lipids, and nucleic acids in microorganisms, inactivating them, but microorganisms may generate tolerance, and photosensitizers may continue to be active in foods entering the human body.