Modeling aflatoxin B production by Aspergillus flavus during wheat malting for craft beer as a function of grains steeping degree, temperature and time of germination.

This study aimed to model the aflatoxin B (AFB) production by A. flavus in wheat grains during malting for craft beer. A total of sixty-four different combinations of grains steeping degree (ST; 41, 43, 45 and 47%), temperature (13, 15, 17 and 19 °C) and time of germination (48, 72, 96 and 120 h), comprising the range of malting conditions that allow the production of quality malt, were assayed. AFB was produced in a range of 15.78 ± 3.54 μg/kg (41% ST, 13 °C for 48 h) to 284.66 ± 44.34 μg/kg (47% ST, 19 °C for 120 h). The regression model showing an acceptable fit to the experimental data (adjusted R 0.84) for AFB as a function of grains steeping degree, temperature and time of germination. Results showed that AFB levels in wheat malt increase with increase of the temperature or time of germination. Within the range of tested malting conditions, no significant effects were observed for steeping degree on AFB levels in wheat malt. The generated model is useful to estimate the AFB levels in wheat malt. Findings highlight overall that if wheat grains are contaminated with A. flavus, AFB might be produced in malt in levels above the limits set by regulatory agencies, regardless the steeping conditions used.