Post Harvest Technology

Handling of Live fish and Shellfish

Removal of off-flavour from fish

Practical control measures:

(i) Control in culture systems - Minimizing feed wastes, exchange of water, chemical control of blue-green algae, increasing turbidity through mechanical agitation or bottom feeding fish.

(ii) Removal from affected fish - Keeping in charcoal-filtered clean flowing water; keeping in pond with frequent exchange of water till flavour improves, keeping in floating bags off the bottom, addition of salt to achieve 10‰ salinity (in closed raceways).

(iii) Removal by processing - Smoking, steam pre-cooking and addition of vegetable oil before canning.

1. Influence of temperature on rate of flavour removal and rate of weight loss of fish; method of sensory evaluation for off-flavour.
2. Requirements: supply of clean oxygen-rich water; temperature control; feeding in prolonged holding.
3. Holding facilities; holding ponds, holding nets, floating boxes, tanks, vats, aquaria. Holding or temporary storage of live fish and shrimps before marketing or processing.
   • Maintenance of good condition of animal;
   • Improvement of quality of flesh,and
   • Minimizing weight loss.

Sorting and Grading

Species-wise and size-wise; grading devices-grading baskets, mechanical graders and grading nets.

Transportation of live fish and prawns

• Transportation of fresh fish
• Containers used; methods of packing with crushed ice.

Fish spoilage

Causes of fish spoilage - autolysis and bacterial spoilage, oxidation and rancidity of fats and protein denaturation; spoilage micro-organisms of fish and fishery products, rigor mortis - pre-rigor, rigor and post-rigor conditions; importance of prolonging pre-rigor and rigor conditions.

Methods of evaluating freshness of fish

Organoleptic, chemical (estimation of TVBN and VAN) and microbiological methods.

Preparation of fish for processing

Checking for off-flavour, grading, stunning, dressing (scaling or skinning, beheading, cutting of fins and eviscerating), washing and cutting; different forms of preparation - whole or round, drawn, dressed, steak, fillets and comminuted.

Preparation of shrimps for processing

Peeling (manual and enzymatic), deveining, washing, different forms of preparation - shell-on, headless, PD, PDC, etc.

Quality control

Methods; national and international standards.

Sanitation and hygiene standards

Sanitation and hygiene standards for handling and processing establishments, containers, transport vehicles and markets

Marketing of fish and shellfish

Importance of consumer research in marketing; marketing patterns based on consumer preferences; packing for the market; use of insulated and refrigerated vans; wholesale and retail marketing.

Last updated: 1-3-2007