KELLEY and HARMON: CAROTENOID CONTENTS 



EXPERIMENTAL PROCEDURE 



1. The shrimp were frozen whole as soon as 

 possible after being caught, then were shipped 

 to the laboratory. They were partially thawed, 

 weighed, and separated according to weights. 

 The shrimp used were about 80 count. All were 

 headed and some were hand peeled to obtain 

 meats. The tails with shells on and the peeled 

 meats were refrozen as needed until analyses 

 could be made. 



2. Whole cooked, hand-peeled frozen shrimp 

 meats were obtained from a commercial proces- 

 sor. This is the conventional, cocktail style 

 product. 



3. Precooked, machine-peeled shrimp were 

 produced under experimental conditions in a 

 commercial plant. Shrimp were landed within 

 24 hr of catching, held overnight without ice, 

 and precooked at 165° F for 10 sec, 110° F for 

 2 min, and machine peeled. The meats were col- 

 lected at the end of the inspection belt and 

 frozen in cans without vacuum. Analyses were 

 made within a few days, after 6 months, and 

 after 12 months of 0° F storage. 



4. Precooked, machine-peeled canned shrimp 

 were produced as described above except they 

 were routinely retorted. The 2-day iced, ma- 

 chine-peeled shrimp are a standard commercial 

 pack from the same lot of shrimp. 



5. The 1-day not iced; 2-day iced ; and 3-day 

 iced, precooked machine-peeled, canned shrimp 

 were also experimentally produced in a commer- 

 cial plant. The 1-day not iced shrimp were held 

 in the wooden boxes in which they were landed. 

 The 2- and 3-day iced shrimp were held in large 

 tanks and ice added as needed to keep them cool. 

 All of these shrimp were precooked at 165° F 

 for 10 sec, 110° F for 2 min, and then routinely 

 peeled and canned. 



All samples were analyzed using the previ- 

 ously described method of determining carote- 

 noid contents. The averages reported in Table 1 



represent 3 to 12 determinations under the given 

 s,ampling conditions. 



' Some of the factors which cause differences 

 in the carotenoid content of shrimp are shown 

 in Table 1. These include several processing 

 variations which can be controlled by processors 

 and fishermen. 



CONCLUSIONS 



The method of determining carotenoid content 

 described is simple and precise and may be used 

 on a variety of shrimp product forms. 



The carotenoid index for Alaska pink shrimp 

 varies from 0.267 in raw tails to 0.059 in ice 

 held, machine-peeled canned shrimp. Correla- 

 tion with subjective color rating is quite good 

 (Collins and Kelley, 1969) . At the higher color 

 levels found in raw, hand-picked, or precooked 

 shrimp, small differences are difficult to detect 

 visually and the determination of the carotenoid 

 index becomes even more useful in evaluating 

 samples. 



Since the carotenoid content is usually closely 

 correlated with other quality characteristics, 

 the carotenoid determination may be useful in 

 making decisions about the best ways to process 

 or handle shrimp. 



LITERATURE CITED 



HORWITZ, W. (chairman and editor). 



1965. Official methods of analysis of the Associ- 

 ation of Official Agricultural Chemists. 10th ed. 

 Association of Official Agricultural Chemists, 

 Washington, D.C., xx + 957 p. 

 Collins, J., and C. Kelley. 



1969. Alaska pink shrimp, Pandalus borealis: Ef- 

 fects of heat treatment on color and machine peel- 

 ability. U.S. Fish Wildl. Serv., Fish. Ind. Res. 5: 

 181-189. 

 Kanemitsu, T., and H. Aoe. 



1958. Studies on the carotenoids of salmon. I. 

 Identification of the muscle pigments. Bull. Jap. 

 Soc. Sci. Fish. 24: 209-215. 



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