waste. The frozen materials from Alaska were collected as described 

 in Section I, "Collection of Raw Materials in Alaska." The Columbia 

 River viscera used in the preparation of the meals was Chinook salmon 

 waste and was obtained from the supply the Leavenworth Hatchery used 

 for its standard production diets. 



For the processing of the air-dried meals the frozen, ground vis- 

 cei^ was thawed at room temperature. Two pounds of viscera were spread 

 on each of nine hardware cloth trays. These loaded trays were stacked 

 in a basket with a conical aluminum drain plate between each tray. The 

 basket was then placed in the vertical pressure cooker and, after vent- 

 ing the ait rapped air, the fish were processed at 15# steam pressure 

 for 10 minutes. The object of the spaced trays and drain plates was, 

 respectively: 1) to subject the material to moderate and uniform 

 heat treatment as possible to facilitate coagulation of the protein, and 

 2) to minimise leaching of the water-soluble materials from the cooking 

 fish by the condensed steam and freed liquor. 



The cooked material was cooled and spread on hardware cloth screens. 

 These screens, loaded with approxiniately one and one-half pounds of mat- 

 erial per square foot of surface, v/ere stacked in trucks and placed in a 

 tunnel-type hot air drier. The meals were dried at 100°F. and 145°F. 

 Drying was continued until the materials contained approximately 10 per- 

 cent moisture, usually one and one-half to two hours . The dried material 

 was ground in a Wiley mill using the 3/l6" hole size screen. AjLl meals 

 were mixed, sampled for ainalysis, packed into tin cans, and stored at 

 O*'?. until used for feeding tests. 



In the preparation of the acetone- extracted meals, enough acetone 

 was added to the thawed ground viscera to coagulate the protein. The sol- 

 ids were allowed to settle and the liquid, consisting of water, acetone 

 and oil separated by decantation. The solid material was extracted twice 

 "ith acetone. This entire procedure was carried out at room temperature. 



The flame-dried salmon offal meal was commercially prepared from the 

 vrtiole cannery waste and is a standard by-product prepared from cannery 

 waste. The history of the raw material used to prepare the meal is unknown. 

 The meal is dried by intense heat with a direct flame. 



The Puget Sound pink salmon viscera was the visceral waste from the 

 "Iron Chink" and was conveyed to a storage tank where the excess water was 

 siphoned off and discarded. The viscera was brought to a temperature of 

 210 F. by injection of live steam. The cooked mass was then pumped to a 

 centirLfugal separator (Sharpies Super-decanter) where the solids were 

 continuously separated from the liquid material, The solids, containing 

 approximately 63.5 percent mcdsttire, were packed into 5-galloncans and 55- 

 gallon drums. These filled containers were frozen and held in fi*ozen 

 storage until the feeding tests were to be made. 



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