616 U. S. BUEEAU OF FISHERIES 



Sometimes winter frozen fish are packed in snow houses and not 

 shipped at once. They may be held for months, packed in snow 

 houses, frozen solid. 



These fish are not glazed, but the conditions under which they are 

 kept virtually preclude desiccation and rusting, so that glazing is 

 scarcely needed. Fish frozen in this way are assured of one great 

 point of superiority — they are absolutely fresh when frozen. The 

 rapidity of freezing, however, may be highly variable, according to 

 temperature and wind velocity. When the temperature is 40° 

 below, the wind blowing a gale, and the fish are not piled, they 

 should freeze rapidly and be of excellent quality. On a day with 

 an air temperature of 10° above and no wind the fish would freeze 

 slowly and would be damaged by internal crystallization. However, 

 the conditions being entirely beyond our control, we may accept 

 them as a bounty, enabling fishermen to earn something in such a 

 winter climate and furnishing the public with an excellent product. 



DEFROSTING AND COOKING FROZEN FISH 



If, while the fish are freezing and during storage no changes take 

 place other than mere solidification, they should, on thawing, return 

 to their original condition; but we have seen that changes of a more 

 or less serious nature may take place in freezing and storage. How 

 may these changes be reversed on thawing and the fish restored to 

 its original condition? 



If fish are frozen rapidly, as in any of the newer rapid-freezing 

 processes, and stored for a short time with a good glaze or covering to 

 prevent drying, they may be defrosted rapidly or slowly, as desired, 

 and will approach their original condition. In fact, a freshly brine- 

 frozen fish may be put in the oven or frying pan while still hard, and 

 it will be in every way indistinguishable from fresh fish. 



EFFECT OF CRYSTALLIZATION AND COAGULATION 



If during slow freezing some of the water separates from the 

 tissues of the fish and freezes as crystals of water ice, on thawing 

 these crystals turn again to water. If this water is to be reabsorbed 

 into the tissues, it must have time. "While it is absorbing the fish 

 must not be squeezed or otherwise disturbed, else the water will exude 

 and be lost. Likewise, if rapidly frozen fish on long storage undergo 

 coagulation with separation of water, the water must be given time 

 to be reabsorbed into the coagulated tissue on defrosting. 



Slow defrosting is preferable, for the reasons given, to extremely 

 rapid defrosting. The writer has observed that rapidly frozen fish 

 that has been stored for more than a month is wet when defrosted 

 in warm air and juice can be squeezed out : but within an hour the 

 juice is reabsorbed and can no longer be squeezed out. Air-frozen 

 fish on defrosting, especially if they have been stored for some time, 

 are exceedingly juicy and will lose some juice with almost any kind of 

 defrosting. This juice contains so much albumen that if heated it 

 will coagulate like the white of egg. It represents not only a loss of 

 weight but a loss of valuable nutrients and savory materials. For 

 example, in a recent test made by the writer a sample of 15 pounds of 

 a commercial brand of air-frozen, fillets of haddock, individually 

 wrapped, was defrosted in the original package. On defrosting the 



