Modeling aflatoxin B1 production by Aspergillus flavus during wheat malting for craft beer as a function of grains steeping degree, temperature and time of germination.

ABSTRACT

This study aimed to model the aflatoxin B1 (AFB1) 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. AFB1 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 R2 0.84) for AFB1 as a function of grains steeping degree, temperature and time of germination. Results showed that AFB1 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 AFB1 levels in wheat malt. The generated model is useful to estimate the AFB1 levels in wheat malt. Findings highlight overall that if wheat grains are contaminated with A. flavus, AFB1 might be produced in malt in levels above the limits set by regulatory agencies, regardless the steeping conditions used.