An evaluation model for the oxidation of frying oil using key volatile aldehyde detected by HS-GC/MS

The volatile aldehydes of 10 commercial oils present during frying at 180 °C were identified using headspace-gas chromatography/mass spectrometry to establish a feasible model for evaluating the oxidation of frying oil. The results showed that the total peak area of aldehydes detected in the 10 oils increased significantly after frying, and this increase was inversely proportional to the polyunsaturated fatty acid content of the oil. The changes in the peak areas of four aldehydes (pentanal, hexanal, (E)-hept-2-enal, and nonanal) common to all 10 oils were different during frying. By combining the correlation analysis of the peak areas of the four aldehydes with the carbonyl value (CV), the feasibility of using pentanal as an index for evaluating the oxidation of frying oil was illustrated. A model was also established for predicting changes in CV during frying based on the peak area of pentanal and the ratio of the initial contents of linoleic acid to palmitic acid and total tocopherols in the oil. This approach could replace the traditional CV measurement method by using high precision mass spectrometry for evaluating the oxidation of frying oil, thus providing a practical evaluation model for managing the quality of frying oil on a routine basis.