- Japan Oil Chemists' Society
- 油化学 (ISSN:18842003)
- vol.23, no.5, pp.290-295, 1974-05-20 (Released:2009-11-10)
It had been found that some particular fish of several different families contain the wax esters as their major lipid type. The interest in deep sea organisms and advancing survey techniques have permitted to extend the occurrence of the wax esters in their lipids. In the fish there is a characteristic pattern in the presence of waxesters in the tissue lipids; namely, the wax esters are the major lipid, type in the muscle but are present trace in its roe, while this pattern is reversed in some fish.As the representative example of the latter, the mullets caught off coast of Mokuzu, Sukumocity, Kochi-prefecture, were collected and analyzed to understand the properties of ovary and other tissue lipids and thereby, to get some informations on the formation of wax esters during the process of maturing.From the biological measurement of mullet, the maturity of roe can be well expressed by the gonad index (gonad weight/body weight ×100, G.I.). It was further found that there is a relation between the gonad index and the wax ester content in roe lipids. Upon measurement of eleven gonads with different gonad indices from 0.28 to 17.65, the wax ester contents in roe lipids varied from 4.6% to 65.4%. This relation was expressed by the following empirical formula, y=62.6 (1-e-x/1.78), where x is the gonad index and y is the corresponding wax ester content in roe lipids.The wax esters of mullet roe lipids consist mainly of C26 to C40 with even chain-lengths. The major esters are C32 and C34, and the sum of both acids exceeds 70% of total, and a little amounts of odd numbered esters exist. The acid moiety of wax esters contains over 30% of C16 : 1 and C18 : 1 as main acids, respectively, while the alcohol moiety consists of C16 : 0 dominantly, as much as 61%. The fatty acid composition of triglycerides is similar to those of the free fatty acids, and the composition of free alcohols rather resembles those of the alcohol moiety of wax esters.Composition of various tissue lipids obtained from the immature (G.I. 0.28) was contrasted with that of mature mullets (G.I. 17.65). In the former there were no particular differences among the various tissue lipids but a small amounts of wax esters were detected in the lipids of liver, intestine contents etc. as well as ovary, while from the latter the wax esters more than 60% were found only in the lipids of ovary. There were no significant differences in other tissue lipids of both the mature and immature mullets.