Abstract: In order to understand the pattern of growth and aflatoxin production of Aspergillus flavus in chili powder matrix, the growth and toxin accumulation data were obtained under varying conditions of temperature (20, 28, 37 and 45 ℃), water activity (0.85, 0.90, 0.93 and 0.97) and pH (4.5, 5.0 and 5.5). The Baranyi and Roberts model was used to estimate the maximum radial growth rate (μmax, mm/d) of colonies. The modified second-order polynomial model, Arrhenius model and third-order polynomial model were used to describe the combined influence of the environmental factors on μmax. Moreover, a second-order polynomial model was developed depicting the effect of the environmental conditions and culture time on aflatoxin production. The results showed that the modified second-order polynomial model had the highest goodness of fit to determine the growth of A. flavus, with coefficient of determination (R2) larger than 0.99. When comparing observed and predicted values of A. flavus, the bias factor (Bf) and accuracy factor (Af) were found to be 1.077 0 and 1.131 9, respectively. The cumulative amount of aflatoxin was accurately predicted by the proposed model with R2 greater than 0.97. These results can provide basic data for the safe storage and processing of chili powder, and also provide a theoretical basis for extending the shelf life of chili powder.

Key words: chili; matrix; Aspergillus flavus; aflatoxin; prediction model