86 BULLETIN 908, IT. S. DEPARTMENT OF AGRICULTURE. 



The damage done to oil sardines by freezing and thawing is negli- 

 gible in comparison with that done to mustard sardines. 



The results of these experiments show that it is most desirable to 

 store sardines at a low, even temperature. 



DECOMPOSITION OF THE FISH. 



The flesh of fish differs in composition from that of animals in 

 that it is relatively richer in gelatin-yielding material (collagen) and 

 contains a smaller proportion of extractives. It is probable that cer- 

 tain bacteria grow more rapidly on fish than on meat, thus explaining 

 the greater rapidity in the decomposition of fish. The end products 

 of decomposition of the flesh of fish are the alkaline substances, 

 ammonia and amines. Fish flesh contains a small amount of am- 

 monia as a normal constituent, and the tissue juices doubtless 

 contain amines, but in such small quantities that their presence 

 in appreciable amounts may be considered as an evidence of decom- 

 position. This is true also of the flesh of the lobster, crab, and 

 shrimp, to which group of marine life the organisms classed as 

 feed for the sea herring belong. 



Indices of Decomposition, 

 ammonia and amines. 



During the course of this investigation a number of determinations 

 of the amount of ammonia and amines present in fresh fish and in 

 fish at various stages of spoilage were made. Fish free from feed 

 and fish containing feed in different stages of digestion, some of them 

 belly blown, were examined. The average of numerous determina- 

 tions showed that the fresh fish contained from 1 .5 to 2 mg of ammonia 

 and amines, as nitrogen per 100 grams of fish, or, calculated to the 

 water and fat free basis, 11 to 12.5 mg per 100 grams of fish. 



The transportation experiments (p. 26) brought out the following 

 facts: In the case of small fish which contained no feed, and were 

 kept, without the addition of salt, at 54° C, the viscera and con- 

 tents decomposed more rapidly than did the flesh. In the case of 

 larger fish, containing a little feed and transported without salt, the 

 ammonia and amines in the viscera and contents increased from 12.6 

 mg in the fresh material to 22.3 mg per 100 grams of material at the 

 end of 12 hours, while that in the flesh increased only from 13 to 

 14.5 mg during the same period. After these fish had stood for 24 

 hours, the flesh showed a decided change, with evidence of marked 

 decomposition. In the case of fish carried in salt (1J sacks per 

 hogshead), a noticeable increase in ammoniacai material, from 11 

 to 18.2 mg per 100 grams, had occurred in the viscera and contents 

 by the end of the 4-hour period of holding. 



Fresh fish containing some feed, but hardly to be classed as feedy, 

 after standing for certain periods of time, showed a marked increase 



