420 MARINE PRODUCTS OF COMMERCE 



curing process continues for several months until the flesh becomes so firm that 

 it cannot be depressed with the fingers. During the long Arctic winters this dried 

 salmon constitutes an important part of the protein portion of the diet of both the 

 native and his dogs. 



Miscellaneous Dried Products. Throughout the Orient the drying of fish products 

 comprises a sizable section of the fishing industries, and dried fish is a staple item 

 in the diet of the people of this region. Although there are many species of fish 



(Photo by C. L. Anderson) 

 Fic. 19-6. Japanese drying sardines at San Pedro, California. 



and the mechanics of handling the products vary greatly, the essential curing 

 process so thoroughly removes the moisture by drying in the open air that the 

 product will keep over an extended period of time. The Japanese dry such fish 

 as cod, herring, mackerel, sardines, albacore, and tuna. 



Dehydration or Artificial Drying. Principles of Dehydration. The basic principle 

 involved in drying fish, whether by natural or artificial means, is the reduction of 

 the moisture content to such an extent that decomposition by both bacterial putre- 

 faction and enzymic autolysis is stopped, or at least sufficiently inhibited to insure 

 reasonable keeping qualities. In natural drying the curing proceeds so slowly in 

 most cases that a certain amount of decomposition does occur before the desired 

 reduction in water content is reached. This is evidenced by peculiar "cured" odors 

 and flavors. These are not considered objectionable by those accustomed to using 

 such dried items in their diet; in fact they may even be relished. However, to the 

 average person they are so objectionable that such products are seldom used. 

 Another objection to natural air-dried fish is that its character is so changed in the 

 curing process that it absorbs water very slowly in soaking and upon reconstitu- 

 tion never attains the original gelatinous character of fresh fish. Upon storage 

 further undesirable changes occur due to certain physical and chemical altera- 

 tions in the flesh and oil of the fish (Tarr, 1943). 



Dehydration, then, consists of the application of artificial drying in such a 

 manner that these objectionable features are overcome. The drying process is 

 speeded up by controlled temperature, humidity, and air velocity. There have 

 been many attempts during the past half century to prepare dehydrated fish prod- 



