Fate of aflatoxin B-1 during the cooking of Korean polished rice

Abstract

The fate of aflatoxin B-1 (AFB(1)), a mycotoxin known to occur in polished rice, during rice cooking was evaluated to determine reduction in AFB(1) residues and mutagenic potentials. The amounts of AFB(1) 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 AFB(1) (mean reduction, 34%) in naturally contaminated polished rice and reduced mutagenicity by ca. 27%. Processing factors (reflecting the removal of AFB(1) 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 AFB(1) 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 AFB(1) than do Americans and thus are at higher risk for AFB(1)-induced health consequences.