Mechanism of palmitoleic acid oxidation into volatile compounds during heating

To better understand the mechanism of palmitoleic acid oxidation into volatile compounds during heating, volatile profiling was investigated by combining thermal-desorption cryo-trapping with gas chromatography–mass spectrometry. A total of 49 volatile compounds were detected and identified during this process, including aldehydes (18), ketones (14), alcohols (9), furans (3) and acids and ester (5). The forming temperature of each volatile was determined. Most of the volatiles with short carbon chains were generated at low temperatures, while those with long carbon chains were generated at high temperatures. Results of principal component analysis show that nearly all of the identified volatiles were considered as the characteristic ones of the high temperature points. Meanwhile, the oxidative products of the C7–C11 saturated and unsaturated aldehydes were also detected and identified during heating to intensively investigate the oxidative mechanism of palmitoleic acid during heating. Results demonstrated that only the C10 saturated and unsaturated aldehydes could continue to be oxidized during heating. Therefore, the oxidation reactions above the secondary level of lipids mainly occurred in the C10 saturated and unsaturated aldehydes.