Fate of aflatoxin B₁ during the cooking of Korean Polished rice

The fate of aflatoxin B₁ (AFB₁), a mycotoxin known to occur in polished rice, during rice cooking was evaluated to determine reduction in AFB₁ residues and mutagenic potentials. The amounts of AFB₁ in three lots of naturally contaminated polished rice from Korea were analyzed by high-performance liquid chromatography after washing and after steaming. An in vitro mutagenicity assay with Salmonella Typhimurium TA100 was used to confirm the results of the chemical analyses. Cooking significantly reduced AFB₁ (mean reduction, 34%) in naturally contaminated polished rice and reduced mutagenicity by ca. 27%. Processing factors (reflecting the removal of AFB₁ residues during processing) for cooked rice were estimated at 0.66 to 0.73, as determined chemically and toxicologically, respectively. The revised Korean provisional daily intake of AFB₁ from consumption of rice as a dietary staple (0.58 to 3.94 ng/kg of body weight per day) is still higher than that reported for foods in general in the United States (0.26 ng/kg of body weight per day). Thus, Koreans probably consume higher amounts of foodborne AFB₁ than do Americans and thus are at higher risk for AFB₁-induced health consequences.