The production of aflatoxin B1 by Aspergillus parasiticus in peanuts and walnuts under the influence of controlled temperature and water activity

Abstract The current study was designed to predict the response of Aspergillus parasiticus and AFB 1 production as a function of temperature (25, 30, 35, 40 °C), water activity ( a w = 0.57, 0.90, 0.94, 0.96) and growth medium in peanuts and walnuts. The fungal growth, counted as infected nut kernels and AFB 1 content was determined using HPLC. About 100 % kernels of peanut and walnut were infected with A. parasiticus at 30 °C with 0.96 a w . The maximum toxin was quantified at optimal 25 °C × 0.96 a w (4780 μg/kg) in walnuts and 30 °C × 0.96 a w (9100 μg/kg) in peanuts. Whereas, the temperatures (<20 °C or >40 °C) and a w (<0.90) doesn’t provide a sufficient environment for the growth of these entities. Additionally, the sample growth medium was found another major factor that affects toxin production, along with environmental conditions. The regression model and two-way ANOVA indicate that temperature, a w and commodity are the significant predictors ( p < 0.05) for fungal growth and AFB 1 production.