Tropical Fish Processing Technology

• The text provides study notes on fish processing technology in the tropics
• The notes cover topics from the development of fish processing technology to quality assurance.

Development of Fish Processing Technology

• Freezing at sea, use of chilled seawater, and on-board fillet processing occurred in the 1950s
• 1970's saw the introduction of meat-bone separators and improvements in surimi production.
• The 1980s and 1990s focused on consolidating existing technologies rather than introducing major new ones.

World Utilization (1985-1993)

• The quantity of frozen fish decreased due to the withdrawal of USSR factory vessels and freezer trawlers
• A shift from cured/canned to fresh fish led to decline in cured and canned product amounts
• Traditional methods like drying, salting, fermentation, and smoking are still common in Southeast Asia.
• Demand is growing for ready to eat products
• The Philippines is the second largest producer of cured fish in Southeast Asia, after Indonesia.
• Philippines has >7,000 islands and 17,640 km of coastline
• The Philippines possesses 290,000 km² of continental shelf area and 2.5M km² EEZ, including territorial waters.
• Inland, the Philippines has 9,000 km² of freshwater bodies and 5,000 km² of brackish water and swamplands
• Philippine waters have >2,000 species of fish, mollusks, crustaceans, and other aquatic life.
• Production of fish sauce (patis) and paste peaks in April and declines by October.

Nutritive Value of Fish

• Fish is healthy due to omega-3 oils, as well as vitamins A, B, iodine, fluoride, selenium and zinc
• Fish is low in calories and fat
• Oysters and mussels contain high iron levels.

Structure of Fish and Fish Muscles

• Fish classes include Cephalaspidomorphi (jawless fish), Chondrichthyes (cartilaginous fish), and Osteichthyes (bony fish).
• Bony fish have skeletons, muscle tissues, skin, fins and viscera
• Edible portions are 60% of the fish, and contain muscle (myotomes), connective tissue (myocommata), and fat
• Fish muscle is 90% white for fast movement and 10% red for slow, continuous movement
• Dark muscle has more lipids, hemoglobin, glycogen and vitamins
• Collagen content is 3% in bony fish and 16% in cartilaginous fish.
• Connective tissue protein makes up 17% of the total protein in mammals.

Composition of Fish

• Fish composition is important to processors, nutritionists, and consumers.
• Composition varies by species, individual, age, sex, environment and season
• Fish protein is 16-22% high-quality, and contains amino acids like lysine and methionine
• Fat content ranges from 0.2-2.5% in fish, rarely exceeding 5% in tropical species
• Fish flesh is 80% water and fat, with long chain fatty acids and high-grade PUFAs (omega-3)
• Omega-3 fatty acids like EPA and DHA support brain growth and prevent heart disease by reducing blood clots
• Fish oil consumption can decrease circulatory diseases, reduce cholesterol levels, and increase HDLP
• Fish vitamins vary by species, typically with red meat rich in A, B1, B2, B12, and D3.
• Skin contains more B1 and B2 , while Liver has more A, D3 and B3
• Shellfish contain more vitamin B complex, especially B6 and B3
• Vitamin A prevents night blindness and promotes healthy skin
• Vitamin B group prevents mental depression and skin issues
• Vitamin D3, specific to fish, aids in calcium metabolism
• Fish contains iodine (for thyroid function), fluorides (for teeth), and selenium (for heart health), but is low in sodium
• Fish is 66-81% moisture and contains taurine, which decreases cholesterol and supports fetal brain development.

Handling of Fresh (Wet) Aquatic Products

• Fish is perishable, and spoilage occurs due to a combination of interrelated processes
• These processes result in formation of hypoxanthine, undesirable flavors, softening, and loss of nutrients
• Spoilage is bacterial, temperature-dependent, and aided by enzymes
• Fatty fish, small fish, and cold-water fish spoil faster
• Live fish flesh is sterile, but surface slime, gills and guts contain bacteria
• Freshwater fish contain gram-positive bacteria, while marine fish contain gram-negative bacteria.
• Bacteria reproduction increases at >4°C, some remain active at 60°C.
• Bacteria such as Alteromonas and Shewanella cause spoilage
• Rigor mortis is the stiffening of muscles after death and any delay prolongs fish keeping time.
• Enzymes present in muscle and gut initiate chemical reactions that lead to autolysis.
• Autolysis can be slowed by refrigeration
• Enzyme activity can be limited via heating, salting, drying, frying or marinating.
• Undrawn fish is vulnerable to tissue degradation and rupture.
• Chemical spoilage mainly occurs during ice or frozen storage, causing rancidity, discoloration and dry texture
• Darkening of red meat occurs due to myoglobin changes.

Hygiene and Sanitation

• Hygiene is crucial to avoid infectious diseases and poisoning hazards.
• Bacterial contamination is a major cause of spoilage
• Fish should be kept clean, and chilled
• Cleanliness is needed at every stage, removing visible dirt and unwanted matter
• Sanitation or disinfection reduces microbes to safe levels using detergents and sanitizers.
• Ideal detergents have good wetting capacity, emulsification power, rinsing properties, and germicidal action
• Good sanitizers or disinfectants are effective, easily dissolved, non-toxic and safe for use

Personal Hygiene

• Good personal hygiene includes bathing and hair washing regularly, keeping nails clean, wearing clean uniforms, and using hair nets
• Hand washing prevents contamination from coughing, sneezing, smoking, handling equipment, and touching raw fish or garbage

Ways of Preparing Fish

• Drawn fish are eviscerated
• Dressed fish are scaled with viscera, fins, head, and tail removed
• Steaks are cross-section slices, while fillets are meaty sides removed from the bone

Handling of Fresh Aquatic Products

• Handle with care to avoid damage and spoilage
• Shellfish need to be alive until processing or cooking
• Sort fish by species and size without delay and keep at low temperatures. These actions, along with general cleanliness, are major determining factors

Oysters and Mussels

• Harvest with care and avoid pulling out hairs, chill with ice, and brush before shucking

Crabs, Shrimps and Lobsters

• Handle crabs delicately, keep them in seawater, and avoid high temperatures for long storage
• Clean and protect shrimp, and chill with crushed ice
• Keep lobsters alive or immobilize them at 14°C, as beheading prevents blackening

Squids/Cuttlefish, and Seaweeds

• Clean well and store squids/cuttlefish at low temperatures with ice
• Wash seaweeds and pack for local consumption

Chilling

• Chilling is a key factor including refrigeration and freezing

Methods of Chilling

• Wet ice (icing) is common and provides cooling through direct contact
• Aim to maintain sufficient ice levels at 0°C with a 1:1 ice-fish ratio
• Arrangements should facilitate drainage, alternating ice and fish
• Chilled Seawater (CSW) uses a mix of seawater and crushed ice
• Refrigerated air can be used in commercial boats
• Dry ice cools through evaporation and is used for air shipments, avoiding direct contact
• Gel ice mats are water-based gels and are used for air transport

Types of Ice

• Ice should be clean, with crushed ice preferred over block ice
• Flake ice provides good contact but clumps easily and tube ice lasts longer

Storing, Sorting, and Containers

• Bulking economizes space but can damage fish
• Shelving works for large, gutted fish
• Boxing is preferred with layering
• Points to consider in container selection are insulating properties, shape, handling, and ease of cleaning

Types of Containers

• Plastic boxes use polymers like polyethylene and polypropylene
• Galvanized Iron Sheet Tubs corrode easily, while Wooden Boxes offer good insulation but are hard to clean
• Coconut, Bamboo or Rattan boxes are cheap but difficult to keep sterile

Types of Insulation

• Insulation aims to slow heat exchange
• Efficiency is measured by thermal conductivity
• Insulating materials include cork, fiberglass, rice hull, kapok, polystyrene, and polyurethane.

Handling and chilling

• Factors to consider are maintaining low temperatures, chilling quickly and minimizing delays

Freezing

• Freezing preserves fish for months by stopping bacteria and enzymatic activity
• Dehydration occurs as water turns to ice

Freezing Process

• The process occurs in three stages
• Removal of Heat slows until the freezing point
• Conversion of water to ice releases heat
• Rapid freezing leads to better quality
• Further cooling lowers the temperature of the frozen fish

Types of Freezing

• Slow Freezing creates large ice crystals (-1 to -5°C)
• Quick Freezing (IQF) processes individually

Freezing Systems

• There are three basic methods: air blast, contact or plate, and spray or immersion Treatment after freezing involves glazing to prevent dehydration, proper packaging and storing around -30°C

Quality Assessment

• Quality assesement focuses on protein changes, lipid changes, and hydration rates of frozen products
• Quick Thawing Is Important

Methods of Thawing

• Thawing can occur in air, submerged in water or through a vacuum

Handling Frozen Fish

• When handling frozen fish do not pry fish apart during thawing
• Containers should be cleaned, and Freeing should not be repeated

Manufactured Products:

• Manufactured Products Can Vary from squid to boneless milkfish

Technical Problems

• Technical problems may result in browning or blackening to tuna products
• Green discoloration of tuna meat can form
• Browning or black spots are known to form in shrimps and prawn.

Research Notes

• Pre-chilling and delaying icing has lasting shelf-life properties
• Cooked shrimps have lasting properties

Salting, Drying and Smoking

• Salting is among the earliest techniques for preserving fish by decreasing wet compounds
• Drying eliminates water, to avoid bacterial growth
• Combining drying, salting, heat treatment and deposition of chemicals preserves by smoking.

Spoiling

Spoilage may result from high moisture content

Types of Aquaculture

• Certain aquaculture is known to result in certain food flavors

classification of fermented products

Classifications of Fermented product vary among fermented

Pickling

• Some methods are known to add enzymes in food production

Quality, Additives and Marketing

• The quality of food production should depend on the value of marketing
• Additives are known to affect the marketability of materials.

Seaweed

• Seaweed is divided into a benthic variety of algae utilized in aquatic habitats
• The nutritive value of seaweed includes protein, minerals, saccharides, vitamins and cellulose

Sea Cucumbers

• Sea Cucumbers vary among species among different regions

Methods of Fish Storage

• Common methods of fish storage include drying, storing in oils and proteins and creating feed

Processing

• The process of fish production takes into account the labeling requirements
• To take precautions avoid toxins by determining the difference in toxicity
• Other types of products can include ammonia