Fish in India is mostly consumed fresh and some are also preserved in the form of pickles or papad and India’s marine fish production has now crossed one million tone marks. Of this, Trash fishes constitute more than 40 %. These are either thrown back into the sea immediately after their catch or utilized wholly or partly as manure. If this fraction is used in the preparation of many usable fish byproducts, it would certainly augment our foreign exchange earning.The modern fish processing industry in our country is four decades old.

Although we have exported dry fish and prawns during pre-independence; the export of marine products rose to 5 lakh tones worth Rs 6,500 crore in 2003. These phenomenal increases in the export of marine products and development in the fish processing industry have been more or less based on a single commodity, prawns which constitute about 10-12% of the total marine catch. However, this modern trend is not so apparent in various other fish products and by-products. One of the important fish byproducts of commercial value is the fish meal, produced mainly from underutilized fish species and by-catch fishes.

Some of the important Fish byproducts of this huge industry are:-

FISH PROTEIN CONCENTRATE

It is a stable protein concentrate prepared from whole fish or other aquatic animals or parts thereof. Protein concentration is increased by removal of water, oil, bones and other materials. Traditionally dried or otherwise, preserved products do not fall within this definition. Development of FPC has paved the way for converting a wide range of whole fish into protein concentrate, which has no resemblance to the original raw material, for human nutrition. It is a gritty, colourless, odourless and tasteless powder. It is stable up to 3-4 years at room temperature without any significant change in flavour.

Development of FPC has paved the way for converting a wide range of whole fish into protein concentrate, which has no resemblance to the original raw material, for human nutrition. It is a gritty, colourless, odourless and tasteless powder. It is stable up to 3-4 years at room temperature without any significant change in flavour.

GELATIN

Gelatin is a protein that lacks in an essential amino acid tryptophan, and hence cannot be considered as a sole source of protein in animal or human nutrition. But it is a relatively high source of lysine and methionine, which are deficient in cereal proteins. However, gelatin finds extensive use in food as also in the formulation of some industrial products. Gelatin can be extracted from the skin and bones of fish.

Uses:-

Gelatin is used in the food industry as a gelling, stabilizing, emulsifying, dispersing or thickening agent.

FISH ALBUMIN

Fish albumin is a product similar to egg albumin in physical and chemical properties. It can be processed out of proteinaceous residue from fish scrap or fish waste. Two grades of fish albumin are produced, the technical grade and the food and pharmaceutical grade.

Uses:-

Fish albumin is widely used in food and pharmaceutical products as whipping, suspending or stabilizing agent.

Food grade albumin is an additive in ice cream, soup powder, puddings, confectionery, bakery products, mayonnaise, custard powder etc.

Isinglass

It is high collagen produced from the air bladders (swim bladders) of catfish, carps, eels, polynemids, sciaenids, sea bass, etc. The bladders are first removed from the selected fish and blood and adhering fat materials are scraped off. They are then cut open and washed thoroughly in running water. Then, the outer black membrane is removed by scraping. Subsequently, the bladders are cut into pieces and are dried in an artificial drier or in sun and stored in suitable containers.

Uses:-

Isinglass, so prepared is used for clarifying beverages like wine, beer, and vinegar.

Isinglass also reduces 2 to 0.05% of the suspended solids in beer and increases filtration rate from 3000 to 11,000 liters.

It can also be used as an adhesive base and in the confectionary product, Indian ink and as an efficient adhesive for glass, pottery, and leather.

Check How to check freshness of fish

Ensilage

It is prepared by converting the entire trash fish or its offal into animal feed by chemical privations. The product has an advantage over the fish meal as the vitamins are not affected in this product which is also free from fish odor.

Uses:-

It can be used in the same way as fish meal. It is generally used in the Danish pig industry and many works has also been done on it.

Hens consuming this laid more eggs and cow produced milk without taint.

Pearl Essence

Guanine is deposited in the epidermal layer and on the scales of most of the pelagic fishes are suspended in a suitable solvent and the product is called pearl essence. The scales are collected from pelagic fish as sardines, mackerels, carps, mullets and ribbon fishes and are preserved in 10-15% common salt solution until they are processed. The scales are soaked in gasoline to separate pearl essence from protein and water.

Uses:-

It is used for photography, ash trays, fishing rods, book covers, textiles, jewellery boxes, umbrella handles and electric light switches.

INSULIN

Insulin is a hormone used for correcting the condition called diabetes mellitus in humans. Fish insulin is more stable as it is not subjected to decomposition by protein splitting enzymes of the pancreas.

Chitosan

The left outs of prawns prior to their freezing in the processing factories such as their head and shell wastes are now used mainly as manure or as a source material for the preparation of feeds. From these wastes, chitosan, a valuable by deproteinization, demineralisation and deacetylation.

Uses:-

Chitosan is now a day’s used as a valuable coagulant aid in the treatment of sewage, etc.

It is used as an additive in the baby food formulations, treatment of wounds and in paper and textile industries and in photography.

Shark fins

The commercial value of the fins depends on their colour, size, variety and quality. Depending on the quality and quantity of rays present in the fins they are broadly classified into 2 verities, generally known as black and white.

Black fins usually fetch a lower price than white fins. The translucent cartilaginous rods embedded in the fins of the shark are the fin rays used in the preparation of shark fin soup. These rays can be extracted from both freshly cut as well as dried fins.

References :

R. Santhanam (1990), Fishery byproduct, Fisheries Science. Pp145-147. Ayyappan S. (2006). Fish Processing Technology. Handbook of Fisheries & Aquaculture. Pp.591-633.

Post By:

Sonali Swain

Food technologist and nature lover

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