Influence of aflatoxin in Nuruk on the safety of starch-based alcoholic beverage.

Nuruk is a fermentation agent used to manufacture alcoholic beverages, which contains a variety of microorganisms. Most microorganisms in Nuruk are useful for the production of alcoholic beverages; however, Nuruk can be infected with Aspergillus flavus, which produces aflatoxin (AF). Therefore, this study analyzed total AF concentrations in Nuruk, the transfer of AF from Nuruk to alcoholic beverages, and AF-producing microorganisms to determine the safety of alcoholic beverages with respect to this toxin. ELISA showed that total AF levels in 14 of 61 Nuruk samples exceeded 15 ppb, the Korean permissible level in cereal products. In alcoholic beverages produced with Nuruk containing AF levels >15 ppb, only AF G1 was detected, at a level of 0.3 ppb, and the transfer ratio of AF G1 was approximately 1.2% to 1.3%. The dominant genera in Nuruk were Aspergillus and Rhizopus. Among 30 strains belonging to Aspergillus, 10 produced only AF B1 at levels of 0.1 to 2.4 ppb after incubation at 25 °C for 8 days on potato dextrose agar plates. Although AF in Nuruk was rarely transferred to alcoholic beverages and the aflatoxigenic strains were found to possess poor AF-producing capacity, further efforts to reduce AF in Nuruk are needed to ensure the safety of alcoholic beverages.