PART III. CHQGCAL PRESERVATION OF SALMON EGGS FOR FISH HATCHERY FEED 

 By George Pigott* and M. E. Stansby** 



Introduction 



Alasksin salmon cannery waste is available in large quantities at 

 a considerable number of canneries 1*1 ich are not equipped with mechan- 

 ical refrigeration. Where refrigeration is available, freezing is the 

 best method of preserving the waste for subsequent hatchery use. Where 

 no freezing facilities are available, the most promising possibility 

 would seem to be the development of some simple, chemical preservative 

 which coTild be applied to the waste. 



Many attempts have been made in the past to develop an effective, 

 cheap chemical preservative for fish waste. When the waste contains all 

 the visceral portions of the fish, the problem is not a simple one since 

 it is not only necessary to stop the action of the bacteria but also that 

 of the very active enzymes present in the digestive system of the fish. 

 Usually, the problem of inactivation of these digestive enzymes is more 

 difficult to overcome than retarding the action of spoilage bacteria. 

 Frequently, success can be achieved only by some drastic treatment whereby 

 the chemical nature of the entire raw materiaJ. is considerably adtered. 

 Such extensive changes would probably prove to be vuidesirable if the pre- 

 served product were to be used for fish hatchery feed because the chemical 

 alteration probably would decrease the nutritive value of the product by 

 destroying vitamins or by rendering them or other nutritive components 

 less digestible. 



With these considerations in mind, it was decided to concentrate 

 efforts toward preservation of the segregated salmon eggs rather than on 

 the entire visceral portion of the waste. Previous tests comparing the 

 nutritive value of salmon eggs with salmon viscera had shown that the 

 former was far superior. Since salmon eggs contain no digestive enzymes, 

 it was felt that there was a far better chance of developing a chemical 

 preservative for the eggs than for the entire viscera. 



* Engineer, Fish and Wildlife Service, Fishery Technological 

 Laboratory, Seattle, Washington. 



*» Chief, Pacific Coast and Alaska Technological Research, Fish and 

 Wildlife Service, Seattle, Washington. 



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