22 U. S. BUREAU OF FISHERIES. 



retarded or arrested by continued low temperatures, sufficiently high 

 temperatures, and by salt. 



9. The damage done by autolysis appears to be in large part pre- 

 ventable. 



10. Fish containing blood, or otherwise not well cleaned, spoil at 

 a lower temperature than those thoroughly cleaned and freed from 

 blood. Thoroughly cleaned fish may be salted at from 90 to 100° F. 

 if pure salt is used. 



11. A method of curing fish embodying the improvements cited 

 was tried in Florida on a small commercial scale with gratifying 

 success. 



12. Scotch-cured herring develop a peculiar flavor which is derived 

 from the fermented or otherwise altered blood. This method has 

 for its aim an alteration to suit particular tastes, while other meth- 

 ods of salting discussed aim at the preservation of the fresh qualities 

 of fish. 



13. There are reasons for expecting that the improvements made 

 in the salting of other fish, particularly those which depend on the 

 use of a very pure salt, will find application in the mild curing of 

 salmon. 



14. Fats undergo certain changes after the fish is salted, resulting 

 in a condition known as " rustino;." Eusting consists of oxidation 

 of fat after the latter has been split into free fatty acids. This split- 

 ting is caused by tissue enzymes in the presence of warmth and mois- 

 ture. Oxidation is brought about through the agency of light in 

 the presence of water. While rusting causes large losses of fish, the 

 means of preventing it, such as tight barrels, air-tight covering, and 

 cool dark storage, are not very satisfactory. The problem demands 

 further investigation. 



15. Fishes whose flesh is not fat and therefore not prone to rust 

 are subject to damage by reddening. Reddening is caused by two 

 organisms, a spirochaete and a bacillus. They may be destroyed by 

 fresh water or live steam. They originate probably in solar sea salt 

 and are apparently not found in mined salt or other purified Ameri- 

 can salt. 



16. Some work has been done toward the development of a process 

 for recovery of salt and other valuable materials from brine. There 

 are a number of promising possibilities which should make this an 

 attractive field for chemists and engineers. 



17. Certain substances are sometimes used as adjuncts in salting 

 fish. Saltpeter preserves a pink color and neutralizes hydrogen sul- 

 phide. Boric acid is used for preserving cod against reddening. 

 Sodium hypochlorite has been proposed as advantageous in conjunc- 

 tion with salt. It may be produced electrolytically from sea water. 



18. The size and shape of the fish influences the rate of penetration 

 of salt into it. Certain mechanical methods of forcing brine into 

 large fish may be advantageous. 



o 



