Effect of Steam Explosion Pretreatment on the Quality and Flavor of Pressed Perilla Seed Oil

The effects of different steam explosion pretreatment durations (30, 45 and 60 s) on the quality and flavor compounds of perilla seed oil were studied. The results showed that steam explosion pretreatment had no significant effect on the composition or content of saturated or unsaturated fatty acids in perilla seed oil, and the acid value and peroxide value of the treatment group were significantly higher than the blank group, but still met the requirements of relevant standards. As steam explosion treatment time rose, the L* value decreased, the b* value increased significantly, and the contents of total phenol and total phytosterol increased significantly. The total phenolic contents at 30, 45 and 60 s were 1.95, 2.29, and 2.77 times as high as that of the blank group, respectively, and the total phytosterol contents increased by 5.36%, 6.48%, and 9.33%, respectively. However, there was no significant difference in the contents of total tocopherol or benzopyrene between the treatment and control groups, and the benzopyrene content in each treatment group was much lower than the national standard limit. A total of 23 volatile flavor compounds were identified by gas chromatography-mass spectrometry (GC-MS), and the types and contents of flavor compounds in perilla seed oil increased significantly after steam explosion. Eleven key flavor compounds were identified by combining odor activity value (OAV) and principal component analysis (PCA), and the major volatile flavor components changed from hydrocarbons and esters to aldehydes and heterocyclic flavor compounds. The overall flavor changed from light fruity and floral aromas to roasted oil-like and nutty aromas. The results of this study provide technical references for the preparation of perilla seed oil.