ANALYSIS OF 1-O-ALK-1-ENYLGLYCEROPHOSPHOLIPIDS OF ALBACORE TUNA (THUNNUS-ALALUNGA) AND THEIR ALTERATIONS DURING THERMAL-PROCESSING

The qualitative and quantitative compositions of 1-O-alk-1-enylglycero lipids of albacore tuna (Thunnus alalunga) were studied along the cann ing process. Ether-linked lipids were found as 1-O-alk-1-enyl-2-acylgl ycerophospholipids (plasmalogens). They were studied by means of their dimethyl acetal (DMA) derivatives resulting from the transmethylation of lipid samples. DMA and fatty acid methyl esters could be simultane ously analyzed by gas chromatography using a polar fused silica capill ary column (SP-2330). Three major 1-O-alk-1-enyl ether chains (16:0'', 18:0'', and 18:1'') were identified in albacore lipids using their ma ss spectre. Phosphatidylethanolamine showed the highest level in plasm alogen content (54.73%). The acyl composition of plasmalogens and diac ylphospholipids was studied. During canning, the plasmalogen content s howed a great decrease along the different steps of processing (raw, c ooked, and sterilized). However, polyunsaturated fatty acids (PUFAs) f rom the polar fraction did not show any difference. These results sugg est that alkenyl ethers are more susceptible to heat damage than PUFA and should be taken into account when damage in the lipid fraction dur ing thermal processing is considered.