On the Studies of Carotenoids of the Salmon-II

Three methods for estimating astaxanthin, the only carotenoid occurring in the muscle of Pacific salmons have been devised as follows: (A) The muscle (5g) was ground in a mortar and the pigment was several times extracted with acetone. The combined acetone extracts were concentrated at room temperature under nitrogen, and the pigment was extracted with petr. ether. This solution was run through a column (3.5×30cm) of cellulose powder (20g), and the column was washed with about 80-100cc of petr. ether to remove fat completely. The pigment adsorbed on the cellulose powder was then eluted with acetone. This acetone fraction was concentrated, and its volume was suitably adjusted with acetone for spectrophotometric measurement with Beckman spectrophotometer. Regarding the difference between values at 478 mμ and 600 mμ as accounting for astaxanthin, the amount of astaxanthin in fresh muscle was calculated using the value of E1%1cm (478 mμ)=2, 200 for pure astaxanthin in acetone. (B) The petr. ether solution of the pigment prepared as A, was added with small amount of anhydrous Na2SO4, and filtered through No. 4 glass filter. After removal of the solvent, the residue was dissolved in a suitable volume of petr. ether for spectrophotometric analysis. The extinction was measured at 470 mμ and 600 mμ, and the calculation was the same as A, except that E1%1cm (470 mμ)=2, 400 was used for pure astaxanthin in petr. ether. (C) The muscle was extracted with acetone as A. The volume of this solution was immediately suitably adjusted for spectrophotometric analysis. Extinction measurement and calculation were made as A. In the methods A and B, the recovery of added pure astaxanthin was 94.4-97.6% and 97.0-98.7% respectively. And there was no appreciable difference among the values obtained by the methods A, B, and C on the same material (Table 1). By these methods, astaxanthin concentration was determined on the dorsal, ventral, and caudal muscles of five species of North Pacific salmons (Table 2), on the muscle of some individuals of red salmon caught at different stations, and also on that of five species from the same station (Table 3). So it was ascertained that the muscle of red salmon is most rich in this pigment, and there was found no distinct relationship between theamount of the muscle astaxanthin and sex, body weight, body length and fattiness.