Abstract: In the present study, we detected the contents of glycoester, glycidyl ester, 3-chloropropanol ester, glycidyl ester, oryzanol, vitamin E, phytosterol and plasticizer in four crude rice bran oils with different acid values, and two oils with distinct acid values were selected from these oils for alkali de-acidification. Changes in the above indicators were analyzed during alkali refining. The results showed that the contents of triglyceride in the four rice bran oils with acid values in the range of 10.34–23.86 mg/g were 70.31%–84.62%, and the total amounts of glycoester and glycidyl ester were 15.38%–29.69%, which increased significantly with the increase of acid value; the content of 3-MCPDE was 1.44–1.98 mg/kg, and the content of GEs was 0.34–0.55 mg/kg, which showed no clear correlation with acid value. After alkaline refining of the selected rice bran oils, the contents of glyceride and diglyceride decreased but only to a limited extent (on average by 3.27%) with the decrease in acid value, while the contents of 3-MCPD ester and GEs decreased significantly by 26.35% and 33.55% on average, respectively, indicating that alkaline deacidification resulted in partial removal of 3-MCPD and GEs. In addition, 64%–76% of oryzanol, 19.5%–29.8% of VE, and 23.6%–39.3% of sterol were lost during the alkali refining process.

Key words: rice bran oil, alkali deacidification, glycoester, glycidyl ester, 3-chloropropanol ester, glycidyl ester, oryzanol, sterol