8 BULLETIN 635, U. S. DEPARTMENT OF AGRICULTURE. 



bility noticeable to the average housewife occurs. This is to be 

 expected, as freezing, unlike most other preservative measures, takes 

 nothing from the fish and adds nothing to it except a thin outer 

 covering of ice which soon melts upon thawing the fish for con- 

 sumption. The low temperatures at which the flesh is held in 

 storage are well designed to prevent chemical or other changes over 

 a number of months. Freezing, however, merely holds the fish in 

 the condition in which it entered the freezing room. Cold can not 

 restore freshness to old fish nor overcome deterioration from care- 

 less handling or exposure to warmth. The freezer can deliver fish 

 practically as good as but not better than that which it receives. 



To determine the behavior of fish under storage the Bureau of 

 Chemistry held fish for the excessively long period of twenty-seven 

 months in cold storage under its control. At different times sample 

 lots of fish were withdrawn and analyzed. These studies showed no 

 significant difference in composition between the frozen fish and 

 fresh fish of the same species. Of special interest is the fact that no 

 loss of those nitrogenous constituents which give to fish its chief food 

 value was noted. 



According to these analyses, the process of freezing and storing 

 causes no appreciable chemical change in those constituents upon 

 which the food values are usually calculated, even when the storage 

 is prolonged for greater periods than are necessary or profitable in 

 commercial practice. In some cases the chemists were able to detect 

 after storage very slight changes in the percentage of ammonia and 

 certain other constituents. These changes, however, affect in no 

 way the food value of the fish, and, in fact, the differences often 

 were not as great in the same lot of fish before and after storage as 

 they were between two individuals of the same species when analyzed 

 in the fresh condition. 



HANDLING OF FROZEN FISH AFTER STORAGE. 



When frozen fish have thawed they are as perishable as fresh fish, 

 and should be consumed as quickly as possible. Even partial thaw- 

 ing lessens greatly the perfect protection of glazing and hard freez- 

 ing. Retailers, therefore, should make every effort to have their 

 frozen fish reach them hard frozen with glaze unimpaired. After 

 the fish reach them the retailers should make very effort to keep 

 them hard frozen and glazed until they are actually sold. This 

 best can be accomplished by ordering frequently and not in excess 

 of immediate sale. Customers should be encouraged to buy fish in 

 the hard-frozen state, either to be thawed out to order by the retailer 

 or. even better, delivered to the housewife hard frozen. She then 

 should place them in a covered utensil in the refrigerator, or other 

 cold place, and allow them to thaw gradually. Fish never should 



