334 



MARINE PRODUCTS OF COMMERCE 



digest the tissues, causing a softening or partial liquefaction and changes of flavor 

 and odor. These changes in red meats are collectively called ripening, and are 

 desirable because they make the meat tender, juicy, and of good flavor. In fish, 

 however, the results are highly disagreeable to the human palate, and ripening 

 or autolysis must be prevented or retarded. A fish whose tissues have been 



1928 1930 1935 1940 1945 



(Courtesy U. S. Fish and Wildlife Service) 



Fig. 16-2. The production of fresh and frozen packaged fish (fillets, 

 steaks, and split butterfly) in continental United States during 1948 totaled 

 193,498,001 pounds, valued at $48,819,726 to the processor. These data do 

 not include the production of pan-dressed fish, which in 1947 amounted to 

 24,906,328 pounds, valued at $2,146,794. When compared with similar data 

 for 1947 (excluding pan-dressed fish), the 1948 production increased 21 per 

 cent in volume and 15 per cent in value. 



The most important species in both quality and value, were rosefish and 

 haddock. Fillets accounted for 95 per cent of the total; steaks, 3 per cent; 

 and spHt ( butterflied ) , 2 per cent. 



partially autolyzed is soft and flabby. Packing fish in ice retards, but does not 

 arrest autolysis. As long as a fish is kept frozen hard, autolysis is all but arrested, 

 but when the fish is defrosted autolysis again sets in. 



Bacterial Invasion and Putrefaction. The principal fields of infection are the 

 gills, slime of skin, and intestinal tract. The invasion by bacteria begins at once 

 if the fish are kept at warm temperatures, and proceeds somewhat more slowly 

 at ice temperature. First the epithelium of the intestines and the intestinal walls 

 are decomposed; the skin and gills are invaded and acquire a sour or putrid odor. 



It is mainly to arrest or retard autolysis and bacterial invasion and putrefaction 

 that low temperatures are employed. Fish packed in ice are still edible after 

 many hours or even several days; but they are in prime condition for only a few 

 hours and are unfit for food, though perhaps not dangerous, after from 1 to 3 

 weeks. Fitness or unfitness for food is, of course, a matter of opinion. If more 

 than the briefest storage is necessary, the fish must be frozen hard and kept in 



