FISHERY BULLETIN: VOL. 69, NO. I 



know, of course, what occurs, because FPC is of 

 value solely as a protein supplement of high 

 quality. 



The aim of this study therefore was to de- 

 termine the effect that storage of food-grade 

 fish in ice has on the chemical composition of 

 the components of the tissue and on the nutritive 

 quality of the protein. We accomplished this 

 aim by comparing FPC made from samples of 

 the ice-stored fish with reference samples made 

 by freeze-drying samples of the fish. We used 

 freeze-drying because we believe that this meth- 

 od of production results in minimum alteration 

 in the samples during drying. 



CHEMICAL COMPOSITION 



Both the proximate composition and the 

 amino acid composition of the samples were 

 determined. 



PROXIMATE COMPOSITION 



As indicated earlier, we used standard refer- 

 ence samples produced under ideal conditions, as 

 a basis on which to evaluate our samples of FPC. 



Standard Reference Sample 



About 600 lb of red hake were caught on Jan- 

 uary 6, 1965, in 25 to 26 fathoms of water oflf 

 the coast of Rhode Island. The fish were di- 

 vided randomly into lots of 100 lb each, were iced 

 immediately, and then were taken to the Bureau 

 of Commercial Fisheries (BCF) (now National 

 Marine Fisheries Service) Technological Lab- 

 oratoiy at Gloucester, Mass., where they were 

 held in ice. 



During the next 11 days, each lot of fish was 

 inspected periodically for freshness by exper- 

 ienced BCF fish inspectors at Gloucester. The 

 factors they considered were (1) damage to the 

 fish, (2) conditions of the skin, eyes, and gills, 

 and (3) texture, odor, and flavor of cooked 

 samples. A numerical score ranging from one 

 to four was used to rate fish of varying quality 

 for each of the factors. Fish of perfect or 

 nearly perfect quality were assigned a value of 

 1, whereas those at the limit of acceptability 

 or beyond the limit were assigned a value of 4. 



Table 1 shows the data on the subjective eval- 

 uation of the raw fish. The samples of fish 

 tested after storage for 11 days in ice were 

 judged to be at the limit of acceptability. The 

 fish that had been stored in ice for 8 days were 

 of acceptable quality and were considered to be 

 of food grade. 



Table 1. — Freshness evaluations of raw red hake stored 



in ice for periods up to 11 days. 



[Each sample had 50 fish.] 



Fish of perfect or nearly perfect qualify were assigned a value of I; 

 ose of unacceptable quality were assigned a value of 4. 



those 



After the iced fish had been inspected for 

 quality, they were shipped in ice to College Park, 

 Md. Each box of fish, upon receipt at College 

 Park, was divided into two gi-oups and were 

 processed immediately— one into a standard 

 reference sample and the other into FPC. 



One portion of 20 lb was selected at random 

 from the group of fish to be used as a standard 

 reference sample. The standard reference 

 sample was prepared by freezing the fish in 

 liquid nitrogen and grinding the whole fish 

 through a Rietz Disintegrator' under a stream 

 of liquid nitrogen, and then freeze-drying the 

 liquid-nitrogen slurry of ground fish. The 

 freeze-drying step was carried out under a pres- 

 sure of 500;* of mercury and at a platen tem- 

 perature of 40° C. The dried samples were 

 then removed from the freeze dryer in an at- 

 mosphere of nitrogen and were sealed in con- 

 tainers. The containers were maintained at 

 — 40° C until the samples were needed. 



The freeze-dried samples were analyzed for 

 crude protein, ash, and volatiles in accordance 

 with standard procedures (Horwitz, 1965). To- 

 tal lipids were determined by the method of 

 Smith, Ambrose, and Knobl (1964). 



Table 2 shows the ])roximate composition of 



' The use of trade names is merely to facilitate de- 

 scription; no endorsement of products is implied. 



146 



