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AQ 100 fish handling processing and transportation
- 1. SOKOINE UNIVERSITY OFAGRICULTURE COLLEGE OF AGRICULTURE DEPARTMENT OF ANIMAL,AQUACULTUREAND RANGE SCIENCES DEGREE PROGRAM;BACHELOR OF VETERINARY MEDICINE COURSE NAME;INTRODUCTION TO AQUACULTURE COURSE CODE;AQ1OO INSTRUCTOR;MADAM ZIPORA EDWIN GROUP ;3 QUESTION 12; INTRODUCTION TO FISH POSTHARVEST HANDLING AND PROCESSING
- 2. Fish Post-Harvest Handling •Refers to activities undergoing after fishes are harvested until they reach consumers. • Includes cleaning, chilling, storage, transport, marketing. • Aims to maintain quality, freshness, safety and reduce post harvest losses.
- 3. Characteristics of Fishas a Food Commodity • Fish flesh is rich in high-quality protein, essential amino acids, omega-3 fatty acids, vitamins (A, D, B- complex), and minerals such as calcium, phosphorus, iodine, and selenium. However, fish spoils faster than meat because of high enzymatic activity, presence of spoilage bacteria(. Psychrotrophic (Cold-tolerant) Bacteria egPseudomonas spp. (most dominant) and rapid oxidation of fats.
- 4. FISH HANDLING • Gentleand hygienic methods to avoid spoilage, contamination, physical damage and quality losses. • Includes catching, bleeding, washing, icing, packaging, transporting and storage • Reduces contamination and maintains quality.
- 5. CAUSES OF FISHSPOILAGE • Fish spoilage is caused by • enzymatic autolysis, • microbial activity, and • chemical oxidation. • Immediately after death, enzymes begin breaking down muscle tissues Bacteria from the skin, gills, and gut multiply rapidly, producing off-odors and toxins. Oxidative rancidity affects fatty fish, leading to unpleasant flavors.
- 6. Postharvest Losses inFish • Postharvest losses include physical losses (discarded fish), quality losses (reduced price), and nutritional losses. • Major causes include poor handling, lack of ice, inadequate storage facilities, poor transportation, and unhygienic processing.
- 7. Handling at HarvestSite •.Objectives of Proper Fish Handling at Harvest Site •Prevent physical damage •Reduce bacterial contamination •Slow enzymatic and microbial spoilage •Maintain market value and consumer safety
- 8. Steps in FishHandling at Harvest Site • 1. Harvesting Method • Use gentle methods (nets, hooks, traps) • Avoid crushing, overcrowding, or rough handling • Minimize stress and injury
- 9. 2. Immediate Killing(Humane Slaughter • Kill fish quickly by: • Percussive stunning • Spinal cord severing • Prevents: • Excess lactic acid buildup • Rapid spoilage • Flesh softening
- 10. 3. Bleeding (ForLarge Fish) Cut gill arches or caudal vessels,Immersion in clean water,Gravity bleeding • Drain blood completely Improves: Flesh color,shelf life,Taste
- 11. 4. Washing andCleaning • Wash fish using clean potable water • Removes: • Slime,Blood,Mud • Do not soak fish for long periods
- 12. 5. Immediate Chilling/ Icing (Most Critical Step) • Apply ice immediately after harvest • Recommended ice:fish ratio = 1:1 • Use: • Crushed ice,Flake ice,Target temperature: 0°C
- 13. 6. Sorting andGrading • Sort by: • Species,Size,Quality,colour. • Remove damaged or dead fish
- 14. 7. Handling andPackaging • Use clean, smooth containers • Avoid wooden boxes (harbor bacteria) • Use food-grade plastic crates • Do not overload containers
- 15. Hygiene at HarvestSite • Clean boats, nets, knives, and tables • Workers should: • Wash hands,Avoid smoking, spitting, or stepping on fish • Protect fish from sun, dust, insects, and animals
- 16. 9. Transportation fromHarvest Site • Transport fish: • Under ice • In insulated containers • Minimize transport time
- 17. Common Mistakes atHarvest Site • ❌ Delayed icing • ❌ Throwing fish on sand or soil • ❌ Using dirty water for washing • ❌ Exposing fish to direct sunlight • ❌ Overstacking fish
- 18. On-site Handling • Washfish with clean water. • Ice fish at 1:1 ratio (ice: fish). • Sort, grade, and store under cold conditions. • Transport in insulated containers.
- 19. Fish Processing • Mechanical,physical, chemical or biological operations aiming at transformation, preserving or enhancing market values. • or Fish processing refers to all operations carried out after harvest to preserve fish, improve shelf life, ensure safety, and add value. • Includes chilling, freezing, salting, drying, smoking, value addition. • it extends shelf life and increases market value.
- 20. Primary Processing These arebasic steps done immediately after fish is harvested to maintain quality, safety and extend shelf life -it involves operations like ; • Gutting, heading, • filleting. • Washing, • de-scaling, • skinning.
- 21. Major Steps inFish Processing • 1. Reception and Inspection • Check freshness (odor, eyes, gills, firmness) • Reject spoiled or damaged fish • 2. Washing and Cleaning • Wash with clean potable water • Remove slime, blood, mud • Avoid excessive washingMaintain cold chain
- 22. Sorting and Grading •3. Sorting and Grading • By species • By size and weight • By quality • 4. Dressing • Includes: • Scaling • Heading • Gutting (evisceration • Filleting
- 23. Secondary processing andPreservation Methods • Involves transforming primary- processed fish into value-added products. • It involes; • Chilling and freezing. • Smoking (hot/cold). • Drying (sun/oven/ • mechanical). • Salting (dry, brine, pickling). • Fermentation, canning, irradiation.
- 24. Fish Preservation /Processing Methods • A. Chilling and Icing • Storage at 0°C • Short-term preservation • Slows microbial growth
- 25. B. Freezing Storage at−18°C or below • Long-term preservation • Common methods: • Blast freezing,Plate freezing,IQF (Individually Quick Frozen)
- 26. C. Drying • Sundrying; • is a traditional method of fish preservation where fish are dried directly under open sunlight to reduce moisture content and inhibit microbial growth. • Solar drying ;is an improved drying method that uses solar energy in a controlled enclosure (solar dryer) to dry fish more hygienically, faster, and efficiently than open sun drying. • Mechanical drying;controlled fish preservation method in which artificially heated air (using electricity, gas, diesel, or biomass) is circulated around fish to remove moisture rapidly and uniformly, independent of weather conditions. – Reduction of moisture content is the end result of drying.
- 27. Smoking • Hot smoking(70–80°C);Cooked, smoked, preserved fish • Cold smoking (30–40°C);Smoke-flavored, uncooked preservation • aim; • Adds flavor and preservative effect
- 28. E. Salting • drysalting • is a fish preservation method in which solid crystalline salt is directly applied to fish to draw out moisture by osmosis, thereby inhibiting microbial growth.Reduces water activity • wet salting • (brining) is a preservation method where fish are immersed in a salt solution (brine), allowing salt to diffuse into the fish tissue.Types of Brining • Weak brine: 5–10% salt • Medium brine: 10–20% salt • Strong brine: 20–25% salt
- 29. F. Fermentation • isa traditional fish preservation method in which microorganisms (mainly lactic acid bacteria and halophilic bacteria) convert fish sugars and proteins into organic acids and other metabolites, creating conditions that inhibit spoilage and pathogenic microorganisms.
- 30. MICROORGANISMS INVOLVED IN FERMENTATION •Microorganisms Involved Lactobacillus spp,Pediococcus spp,Leuconost spp,Halophilic bacteria,Yeasts (in some products) • General Procedure • Fresh fish are washed and dressed • Fish are mixed with salt (5–25%) • Fish are packed tightly in containers • Kept under anaerobic or semi-anaerobic conditions • Fermentation allowed for weeks to months • Final product develops characteristic flavor and aroma
- 31. G. Canning • Heatprocessing in sealed container • Sterilization destroys microorganism • Long shelf life
- 32. H. Pickling • is afish preservation method in which fish are preserved by acidification, usually using vinegar (acetic acid), often in combination with salt, sugar, spices, and sometimes oil, to inhibit microbial growth. • Principle of Fish Pickling • Preservation is achieved by: • Lowering pH (≤4.5) → inhibits spoilage and pathogenic bacteria • Salt addition → reduces water activity • Spices → provide antimicrobial and flavoring effects
- 33. Common Processing Defects •rancidity;refers to the decomposition or spoilage of fish fats (lipids), leading to unpleasant odors, flavors, and reduced quality. It is one of the main reasons fish becomes unacceptable for consumption even before microbial spoilage becomes severe. There are two main types of rancidity in fish: hydrolytic and oxidative • texture softening;refers to the loss of firmness or structural integrity of fish muscle, which makes the flesh soft, mushy, and less appealing. It is a major quality deterioration that affects shelf life, often linked to both post-mortem changes and microbial activity. • Off-odors; • Insect infestation
- 34. Importance of FishProcessing • Reduces post-harvest losses • Improves food security • Enhances export quality • Creates employment • Increases income
- 35. FISH PROCESSING EQUIPMENTS •1. Pre-Processing / Receiving • Equipment used right after catch: • Ice machines & flakers – for rapid chilling of fish on boats or at receiving stations. • Holding bins and chill tanks – to keep fish fresh before processing.
- 36. EQUIPMENTS CONT......... • Cleaning& Gutting • Removes scales, entrails, and preps the fish: • Descalers – roll or blade systems that remove scales fast. • Fish gutting machines – automatically remove internal organs. • Washing systems – high-pressure water sprays and conveyors for cleaning
- 38. Filleting & Cutting •For boneless portions and uniform cuts: • Mechanical filleting machines – produce fillets with minimal labor. • Butterfly cutting machines – open fish like a book for specific products. • Portion cutters/slicers – cut fillets into consumer sizes.
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- 40. Chilling & Freezing •Preserves quality and safety: • Blast freezers – rapid freezing to −18 °C or lower. • Plate freezers – fish pressed between cold plates. • Cold storage rooms – large freezers for bulk product storage
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- 42. 7. Packing &Packaging • Preparing for sale and distribution: • Vacuum pack machines – extend shelf life • Skin-pack machines – attractive retail packaging. • Tray sealers – lock fish in trays with protective film. • Weighing and labeling systems – for accurate portioning and traceability.
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- 44. Value Addition Some ofthe products after fish value addition includes, • Fish sausages, • fish balls, • fish fingers. • Marinated fish, • smoked fish. • Fish powder/flour.
- 45. Factors Affecting Handling •Temperature, • hygiene, • time to icing. • Species (fatty fish spoil faster). • Physical damage during harvest.
- 46. Importance of properhandling and processing • Reduces losses • improves food security. • Improves quality and safety. • Increases market value and income.