114 THE FISHING INDUSTRY 



during the salting process, a thoroughly cleaned and 

 washed fish is, after salting, much whiter in appearance 

 and has a finer taste. 



Many fish are skinned before they are salted. It has 

 been observed that a skinned fish will cure almost 

 twice as quickly as an unskinned fish. This is because 

 salt penetrates the meat of the fish at approximately 

 twice the rate at which it penetrates the skin. It is 

 desirable, therefore, particularly in hot climates, to skin 

 the fish before salting. This, of course, is only com- 

 mercially practicable with certain large kinds of fish 

 such as cod. 



The Reddening of Salted Fish. Salted fish some- 

 times undergo a change, either during the salting 

 process if improperly carried out, or more generally 

 in the store, which is characterized by the development 

 on the surface of the fish of irregular red and brown 

 patches. This reddening occurs not only on the fish, 

 but also on the floors and walls of the curing factories, 

 on the sides and decks of fishing boats, and even on the 

 salt itself. It occurs most readily in warm weather. 



The reddening has been shown to be due to the growth 

 of a micro-organism (a micro-coccus) . With this micro- 

 coccus are generally associated a bacillus and a 

 micro-fungus which produce the brown mould on the fish. 



Fish become infected with these micro-organisms by 

 contact with boats or docks or warehouses. 



Every precaution should be taken to keep such 

 places clean and properly disinfected. 



The " rusting " of fatty fish, e.g. herring, is due to 

 the oxidation of certain free, fatty acids split off from 

 the fats by enzyme action. 



