Lipidklasser og fettsyresammensetning i brunpølse (Cucumaria frondosa)

Abstract

Different species of the sea cucumber are a well utilized resource in eastern parts of Asia, but not much used in western parts of the world. The annual harvest of sea cucumbers in Asian waters has been estimated to be over 100,000 tons. This has led to overfishing and decreasing catches. As a result, a demand for new fishing areas has occurred. Different species of sea cucumbers are observed in significant amounts along the Norwegian coastline and in other parts at the North Atlantic Ocean. Occurrence and demand indicates that sea cucumbers may become a new export product from Norway. One challenge is to develop good and effective harvesting methods for the sea cucumber (Cucumaria frondosa). For the most it is considered as a bycatch in context with more commercial fishery. The value of seafood can to a certain degree be determined by the kind of lipids and fatty acid that are present in the actual organism. Long chained omega-3 fatty acids are of special interest.

The aim with the project was therefore to determine the lipid content and to analyze lipids from the sea cucumber with the use of thin layer chromatography and gas chromatography. The lipids were extracted and analyzed with the production of fatty acid methyl esters for further analysis with gas chromatography. The fatty acids from Cucumaria frondosa were identified by comparing observed retention times with retention times of known fatty acid methyl ester standards. The extracted oil was separated in the different lipid classes with the use of solid phase extraction. The fatty acid composition from each fraction was further analyzed by producing fatty acid methyl esters for gas chromatography.

The analysis showed that the content of total fat was on average ~3.5 % based on freeze-dried material, and the content of long chained omega-3 fatty acids in Cucumaria frondosa was relatively high compared to the total fatty acid composition. Of the polyunsaturated fatty acids, in the total amount, EPA 20:5 n-3 (33 %) was the most abundant fatty acid. The relative amounts of the different fatty acids were different in the different lipid classes. EPA was now present with an amount of 70 % in the fraction consisting of polar lipids and only 11 % in neutral lipids. The most dominant lipid classes were polar lipids including phospholipids (~ 40 %) and free fatty acids (~ 20 %).