Abstract: Steam explosion pretreatment was employed for Camellia oleifera seeds, and the effects of different steam pressure levels and holding time on the yield, physicochemical properties, bioactive substance contents of tea seed oil were explored, as well as the internal factors that affect the change in tea oil quality. The results showed that the oil yield increased with steam pressure up to 1.6 MPa and then decreased. The maximum extraction efficiency was obtained when the pressure holding time was 30 s. Therefore, 1.6 MPa and pressure holding time of 30 s could be considered as the optimal steam explosion conditions for tea seeds. Steam explosion pretreatment reduced the acid, peroxide value of tea seed oil, and increased iodine value and the contents of polyphenols, squalene and vitamin E. Scanning electron microscopy revealed that steam explosion pretreatment made the surface of tea seeds rougher and destroyed the cell structure, thereby promoting the release of oil and bioactive substances. In addition, steam explosion accelerated the Maillard reaction of tea seed oil. Therefore, steam explosion could be an effective method for the extraction of tea seed oil and the release of bioactive substances.

Key words: steam explosion, tea seed oil, physicochemical properties, bioactive substances, Maillard reaction