Isolation and identification of volatile flavor compounds in commercial oil‐free soybean lecithin

Volatile compounds were isolated from 150 lb of commercial oil‐free soybean lecithin by vacuum distillation. The isolated volatile compounds were subjected to extensive gas chromatographic fractionation, and the pure fractions thus obtained were identified by mass spectrometry. A total of 79 compounds have been identified. Most of the compounds identified can be postulated as autoxidative decomposition products of unsaturated fatty acids of phospholipids. Isophorone, an acetone‐derived compound, was shown to be predominantly responsible for the undesirable flavor of oil‐free soybean lecithin. Several nitrogen‐containing compounds, e.g., nitriles, acetoxime and 4,5‐dimethylisoxazole, were identified as unique volatile compounds from phospholipids.