528 u - s - BUREAU OF FISHERIES 



finding is that rapidity of freezing should be obtained by other 

 means than excessively low temperatures. 



CHANGES THAT AFFECT THE FOOD VALUE OF FISH 



Among the changes already referred to that affect the food value 

 of frozen fish the loss of juice caused by crystallization and the 

 degradation of fats are the most important. The juice that runs 

 out of a frozen fish on defrosting contains so much albumen that 

 it coagulates like white of egg when it is heated. The fats, being 

 partly oxidized, have lost part of their fuel value and interfere 

 with digestion. 



On devoting attention particularly to the protein constituents of 

 fish, several chemists have found no significant changes that could 

 affect food value. 21 Their conclusions are based largely on a study 

 of the nitrogenous constituents. There is no doubt that changes 

 that affect food value may and do occur in frozen fish, and that the 

 seriousness of these changes depends on the methods of freezing 

 and storage. That fish can be so frozen and stored that no important 

 change will occur that would affect their food value is likewise well 

 established. 



DESIGN, CONSTRUCTION, AND EQUIPMENT OF FISH 



FREEZERS 



The design, construction, and equipment of plants for freezing 

 fish is a subject the adequate treatment of which is beyond the scope 

 of the present work and must be left to refrigeration engineers, who 

 are nearly always called upon where questions arise or plans for 

 construction are to be made. However, a brief discussion of some 

 aspects of the subject may be useful to the readers to whom this 

 work is addressed. 



LOCATION 



Fish freezers should be located with respect to accessibility to 

 boats that bring in fish, railroad tracks and wharves for cargo ships 

 for transportation, an adequate source of clean water, and avail- 

 ability of coal or electric power and labor. A water-front location 

 is most to be desired, of course, but it is not always available. The 

 nearer to the point of actual production of fish that a freezer can 

 be located the better in general, though public warehouses are 

 located conveniently near wholesale fish markets. As large volumes 

 of water are required for the condensers, it is economical to have 

 access to a lake, river, artesian well, or other free water, which 

 need not be highly pure, and also to filtered pure water for washing 

 the fish. 



a C. S. Smith, " A study of the influence of cold-storage temperatures upon the chemi- 

 cal composition and nutritive value of fish." Biochemical Bulletin, Vol. Ill, 1913, pp. 

 54—68. New York. W. A. Perlzweig and W. J. Gies, " A further study of the chemical 

 composition and nutritive value of fish subjected to prolonged periods of cold storage." 

 Ibid., pp. 69-71. E. D. Clark, L. H. Almy, and M. E. Pennington, " The commercial 

 freezing and storing of fish." U. S. Department of Agriculture, Bureau of Chemistry, 

 Bulletin 635, 1918. Washington. E. D. Clark and L. H. Almy "A chemical study of 

 frozen fish in storage for short and long periods." Journal of Industrial and Engineering 

 Chemistry, vol. 12, 1920, pp. 656-663. Easton. L. H. Almy and E. Field, " Preservation 

 of fish frozen in chilled brine. II. The keeping quality of the fish." Journal of Industrial 

 and Engineering Chemistry, vol. 14, p. 203, 1922. Easton. 



