Abstract: Using rice germ as raw material, the rice germ oil rich in tocopherol was extracted by ultrasonic-assisted hydroenzymatic method.Compared with the conventional aqueous enzymatic method, the extraction rate increased from 87.4%±0.04% to 92.1%±0.03%. According to the single factor experiment, it was found that when the mass ratio of cellulase and neutral protease was 1: 1, the combined enzyme addition amount was 1.2%, the material-liquid ratio ratio was 1: 5, and the enzymolysis time was 3 h. The rice germ oil extraction rate is 87.4%±0.04%.At the same time, through transmission electron microscopy observation, the separation of fat and protein from rice germ treated with ultrasound was obvious. Using response surface optimization, it was found that the influence of various ultrasonic factors on the extraction rate of rice germ oil was as follows: ultrasonic power> ultrasound temperature> ultrasound time.Under the ultrasonic temperture of 55℃, ultrasonic power of 400 W, and ultrasonic time of 20 min, the extraction rate of rice germ oil was 92.1%±0.03%.Ultrasound-assisted extraction of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in rice germ oil was 20.62%, 39.62%, and 37.46%, respectively. The contents of γ-oryzanol, phytosterols and total tocopherols in rice germ oil extracted by ultrasound-assisted extraction were 490.00 mg/100g,384.19 mg/100g and 93.01 mg/100g, respectively.

Key words: rice germ oil, ultrasonic, aqueous enzymatic method, solvent-free, extraction rate