Production of aflatoxin B_1 and B_2 by Aspergillus flavus in inoculated wheat using typical craft beer malting conditions

摘要

The production of aflatoxin (AF) B_1 and B_2 was determined during malting of wheat grains artificially contaminated with a toxigenic A. flavus strain (CCDCA 11553) isolated from craft beer raw material. Malting was performed in three steps (steeping, germination and kilning) following standard Central European Commission for Brewing Analysis procedures. AFB_1 and AFB_2 were quantified in eleven samples collected during the three malting steps and in malted wheat. Both, AFB_1 and AFB_2 were produced at the beginning of steeping and detected in all samples. The levels of AFB_1 ranged from 229.35 to 455.66 ug/kg, and from 5.65 to 13.05 μg/kg for AFB_2. The AFB_2 increased during steeping, while no changes were observed in AFB_1 Otherwise, AFB_1 decreased during germination and AFB_2 did not change. AFB_1 and AFB_2 increased after 16 h of kilning at 50 ℃ and decreased at the end of kilning, when the temperature reached 80 ℃. The levels of AFB_1 wheat malt were lower than those detected in wheat grains during steeping; however, levels of both AFB_1 (240.46 μg/kg) and AFB_2 (6.36 μg/kg) in Aspergillus flavus inoculated wheat malt exceeded the limits imposed by the regulatory agencies for cereals and derived products.