NUTRITIVE VALUE OF FISH AND SHELLFISH 



523 



Table 16. — Variation in composition of different parts of the same fish 

 [Analyses of the edible portion on the fresh basis] 



In the case of the white and red chinook salmon there was a varia- 

 tion of almost 100 per cent in the fat content of the flesh taken from a 

 slice near the tail as compared with a slice taken near the head. In 

 the case of the yellowtail there was some variation, but less, between 

 slices taken from the tail and the middle of the fish. The analyses of 

 different parts of the skipjack are rather surprising in that the fat 

 content in the belly pieces is larger than that of the dark meat. It is 

 one of the characteristics of the mackerel and herringlike fishes, which 

 include in the two groups mackerel, tuna, herring, sardines, shad, 

 etc., all fishes of great economic importance, that they have a consid- 

 erable lateral strip of dark meat which is known to be very rich in fat. 

 In the white meat of the skipjack only 15.39 per cent of fat was present 

 as compared with 22.38 per cent in the dark meat. In the case of the 

 small fishes this variation in the individual part of the fish makes very 

 little difference to the consumer because practically the whole edible 

 part of the fish is consumed. On the other hand, where larger fish 

 are canned or sold fresh in the form of slices this variation assumes 

 gi'eater proportions. 



FOOD VALUE OF FISH AND SHELLFISH COMPARED WITH THAT OF 

 OTHER FOOD PRODUCTS 



In order to appreciate the real significance of fish in the diet it is 

 necessary to make some comparisons in highly condensed form 

 between the composition of fish and that of common animal and 

 vegetable foods. We have already seen that the great value of fish 

 is their content of protein, in the first place, and, in the second place, 

 that the proteins of fish, like those of meat, contain essential nitrog- 

 enous substances like the amino acids tryptophane, cystine, and 

 histidine, without which the body can not replace its wear and tear 

 and either develop or function normally. 



There is a great lack of carbohydrates in fish when compared with 

 vegetable products. On the other hand, it is not at all necessary for 

 fish or meat to compete with vegetable products in the matter either 

 of fat or of carbohydrates, as it is commonly known that foods of 

 vegetable origin are primarily of the carbohydrate or starchy type; 

 furthermore, vegetable fats are relatively cheap. Some fish contain 

 as much or more fat than meat, but generally speaking thev do not. 

 Fish can compete with meat in the dietary on the basis of the cost 



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