Analysis of 1-O-alk-1-enylglycerophospholipids of albacore tuna (Thunnus alalunga) and their alterations during thermal processing

Abstract

The qualitative and quantitative compositions of 1-0-alk-1-enylglycerolipidosf albacore tuna (Thunnus alalunga) were studied along the canning process. Ether-linked lipids were found as 1-0-alk-1-enyl- 2-acylglycerophospholipids(p lasmalogens). 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 simultaneously analyzed by gas chromatography using a polar fused silica capillary column (SP-2330). Three major 1-0-alk-1-enyl ether chains (16:0”, 180”, and 18:l”) were identified in albacore lipids using their mass spectra. Phosphatidylethanolamine showed the highest level in plasmalogen content (54.73 5% 1. The acyl composition of plasmalogens and diacylphospholipids was studied. During canning, the plasmalogen content showed a great decrease along the different steps of processing (raw, cooked, and sterilized). However, polyunsaturated fatty acids (PUFAs) from the polar fraction did not show any difference. These results suggest that alkenyl ethers are more susceptible to heat damage than PUFA and should be taken into account when damage in the lipid fraction during thermal processing is considered.