Edible fish are categorized as either fin fish or shell fish. The term fin fish refers to the fishes that have bony skeleton. Shell fish is used to designate both mollusks and crustaceans.
Fish is an excellent source of protein due to its quality and quantity. They contain around 20% protein. Fish contains less amount of fat compared to meat and poultry. The lipid content of both fish and prawns is very low and varied within a very narrow range of 1-28%. Fish is rich in calcium particularly small fish when eaten with bones. Fish liver oils are excellent sources of fat soluble vitamins. Rohu contains vitamin C. Fish are food sources of niacin and vitamin D.
NUTRITIVE VALUE OF SEAFOODS
Fish is considered in prime condition for upto three hours from catch, in average condition from three to six hours and on the way to spoilage from the sixth hour.
Growth of microorganisms like bacteria multiply and attack all tissues also enzymes affect of the quality.
Due to the production of trimethylamine by the action of bacterial enzymes on phospholipids and choline present in fish off flavour is produced.
PRESERVATION AND STORAGE
Fish spoils quickly and should be used as soon as possible. It should be kept covered in the coldest part of the refrigerator for no longer than 2 days. Prepackaged fish and shellfish can be refrigerated in the original package for a short time. Fish wrapped in butter paper should be taken out and wrapped in aluminium foil and plastic wrap. Frozen fish maintains good quality when placed in the freezer immediately after purchase. Freezer temperatures of 00 F or lower are necessary to prevent loss of colour, texture, flavour and nutritive value. Cured fish is best kept covered in the refrigerators. Open canned fish should be used up immediately or refrigerated.
The dressed fish or fillets are preserved by coating with salt powder in the ratio 1 part of salt to 3 parts of fish. The salt powder should contain sodium benzoate.
Fish can be preserved by canning, chilling, freezing and curing. Unlike most foods, the enzymes of fish operate at about 50 C, the temperature of the water from which they came. In order to keep fish for any length of time, they must be frozen, canned or cured.
In canning, fish is dressed and washed.
Because, the enzymes that cause spoilage of fish are active at low temperatures and because fish oils become oxidized at fairly low temperature, fish catches subjected to temperatures above freezing are given to fast deterioration.
The freezing of fish greatly extends the period of storage and is effective in keeping the fish in a condition similar to that of fresh fish.
Salting, drying, pickling or smoking can cure fish.
Pickling or smoking
Fish allowed to remain in the salt solution are said to be pickling, e.g. pickled herring, sprats, mackerel and salmon.
Salting and drying
Salting and drying of fish are the most important methods of fish preservation.
BY-PRODUCTS AND VALUE ADDITION OF FISHES
DETAILS OF FISH AND FISHERY PRODUCTS