Abstract: Four methods were compared for their removal efficiencies for aflatoxin B1 (AFB1) from peanut oil as well as their effects on the acid value (AV), peroxide value (POV), vitamin E (VE) content and phytosterol content of peanut oil. The mechanism of AFB1 removal by alkali treatment was explored, and the safety, free alkali residue and flavor of peanut oil after being treated with alkali were further evaluated. The content of AFB1 in crude peanut oil was 21.50 μg/kg, and decreased to 2.00 μg/kg (removal efficiency of 90.7%) after 30 min alkali treatment at pH 13.44 with a liquid-to-solid ratio of 10% (m/m). After one adsorption cycle with 2.0% (m/m) bentonnite for 30 min, the removal efficiency of AFB1 was 99.4% and the residual AFB1 level was 0.13 μg/kg. After two adsorption cycles with bentonite at 1.0% first and then at 0.5% for 30 min each cycle, the removal efficiency of AFB1 was 99.5% and the residual AFB1 level was 0.10 μg/kg. Alkali refining and deacidification at 50 ℃ with 0.8% excess alkali for 30 min decreased the AFB1 content in peanut oil to 0.10 μg/kg, with a removal efficiency of 99.5%. The retention rate of vitamin E in peanut oil treated with alkali was the highest among the four methods. Sensory evaluation indicated that alkali treatment also resulted in the lowest flavor loss of peanut oil.

Key words: peanut oil, aflatoxin B1, alkali treatment, vitamin E, phytosterol, peanut oil flavor substances