Characterization of methanolysis products from plasmalogenic lipids in horse muscle tissue

Muscle tissue is known to contain plasmalogenic lipids. Traditional methodologies for the analysis of lipids in muscle consists of methanolysis followed by gas chromatography (GC). The resultant dimethylacetals (DMA) are difficult to resolve because of extensive overlap with fatty acid methyl esters. In this study a new two-step procedure was applied to isolate DMAs from FAMEs from methanolysed horse muscle lipids (n=48) after saponification and solvent partitioning. Both total and isolated DMAs were analysed by GC and the extent of overlap was evident. The total methylated mixture was also analyzed using GC with online reduction (GC-OR x GC) which confirmed the identity of the FAME, DMA and aldehyde products. The DMA content in horse muscle tissue was found to be 55.7 mg DMAs in 100 g of meat, or 3.10 % of total lipids. The saturates 16:0 and 18:0 were the predominant DMA isomers, and 18:3n-3 and 18:2n-6 DMA were identified in this tissue. Samples with a higher (> 3 g/100 g of meat) intramuscular fat (IM) content showed a lower (p ≤ 0.05) absolute content of the DMAs compared to samples with lower IM fat content (15.3 vs 29.3 mg/g of fat, respectively).