A STUDY OF THE LIPIDS AND CAROTENOPROTEIN IN THE PRAWN, PENAEUS-JAPONICUS

The lipid and fatty acid composition of the hepatopancreas and muscle of the prawn, Penaeus japonicus, were analyzed. The hepatopancreas was the main lipid storage organ, triglycerides and phospholipids being i ts major lipid components, while muscle contained mainly phospholipids . The fatty acid compositions of total lipids from the hepatopancreas and muscle were similar to those in other marine animals. The major fa tty acids were palmitic (16:0), oleic (18:1n-9), eicosapentaenoic (20: 5n-3), and docosahexaenoic (22:6n-3) acids. The monoglycerides, diglyc erides, triglycerides, and cholesterol esters from the hepatopancreas and muscle exhibited similar fatty acid patterns, but each lipid fract ion was characterized by a specific paraffin chain composition. A blue carotenoprotein (lambda(max) = 640 nm) containing astaxanthin was als o extracted and purified from the hypodermis of the prawn. This blue c arotenoprotein has a molecular weight of ca. 280,000, which is much lo wer to those given for other crustaceans. The carotenoid prosthetic gr oup was released from the carotenoprotein by the addition of acetone, and showed a hypsochromic shift to 470 nm and the characteristic shape of free ketocarotenoids. TLC, infrared spectroscopy, chemical reducti on, spectrophotometry, and qualitative analysis by HPLC were used to i dentify the astaxanthin as a unique chromophore group of the blue caro tenoprotein. Moreover, HPLC studies suggested all-trans-astaxanthin to be the main component, which was accompanied by an epimer and its cis -isomer.