IN-SITU PREPARATION OF FATTY-ACID METHYL-ESTERS FOR ANALYSIS OF FATTY-ACID COMPOSITION IN FOODS

Lipid extraction preceding fatty acid methyl esters (FAME) preparation for gas chromatography is time-consuming and cumbersome. We omitted the lipid extraction and performed in situ transesterification (ISTE) by heating lipid-containing foods at 90 degrees C for 10 min after adding 0.5N NaOH in methanol for methanolysis and continued heating another 10 min for further methylation after adding 14% BF3 in methanol. FAME prepared by ISTE showed fatty acid composition virtually identical to FAME prepared after lipid extraction from powder, liquid, phospholipid-rich, and tissue products. Due to its simplicity, speed, and reduced organic solvent usage, ISTE should be useful to determine overall fatty acid composition of foods.