78 BULLETIN 908, TJ. S. DEPARTMENT OF AGRICULTURE. 



third amines. During storage at room temperature the proportions 

 appeared to change slowly, until after a long period of standing the 

 total alkaline material was about half ammonia and half amines. 



When stored at a temperature just above freezing, the total quan- 

 tity of volatile alkaline materials was greatly reduced, as compared 

 with that produced at ordinary temperatures. 



Sardines stored just above a freezing temperature for 32 months 

 contained in most cases less volatile alkaline material than was 

 found when they were held at room temperature for a period of 15 

 months. The relative amounts of ammonia and amines formed at 

 the lower temperature of storage remain the same as the total vola- 

 tile alkaline material formed while standing at room temperature. 

 The total amines composing this volatile alkaline material consisted 

 mostly of triamine (practically 80 per cent). Monamine and diam- 

 ine also were present during the earlier period of storage ( 15 and 18 

 months), but in much smaller quantities. At the end of the 32- 

 month storage period no monamine was found, but the diamine in 

 some instances had increased 50 per cent or more. The difference 

 in the rate of formation of ammonia and of amines at a lower tem- 

 perature of storage and at room temperature suggests that these 

 changes may be caused bj 7 bacterial growth, although it is more 

 probable that this action is associated with detinning and adsorp- 

 tion of tin by the fish protein. 



When the cans of long standing co m mercial packs were opened 

 the fish constituting the 4- and 6-year-old goods were decidedly soft. 

 These showed the presence of the largest amounts of amine. 



The quantity of ammonia and amines in the canned sardines also 

 has a decided bearing upon the detinning of the interior of the cans 

 (p. 82). 



It is planned to continue the studies on the relation of detinning 

 to the formation of ammonia and amines in canned fish. 



Effect of Freezing and Thawing on Sardines. 



To determine the effect of freezing and thawing upon sardines, 

 cans from each of the packs put up under the drying experiments 

 (p. 51) were frozen and thawed, after which they were compared 

 with cans of the same goods which had not been frozen. Three lots 

 were employed. In one the sardines were frozen and thawed twice, 

 in another three times, and in the third six times. 



The general appearance of the oil sardines which had been frozen 

 two, three, and six times was practically the same as that of the fish 

 which had not been frozen. On closer examination, however, cer- 

 tain changes in the texture of the meat were readily recognizable. 

 It was apparent that the texture of the fish which had been insuf- 

 ficiently dried was partially destroyed when frozen and thawed twice, 



