Establishment And Application Of The Predictive Models Of A.flavus In Wheat

The fungal distribution in wheat, isolation and identification of main fungal-mould of 4 kinds of wheat were studied in this paper. The overall goal was to determine the objective microorganism in growth predictive model. According to the gradual-approach method, the Aspergillus flavus has been designated as the objective microorganism .Growth predictive models were established based on eight different temperatures and three relative humilities according to the literatures. The results showed that the effects of simulation by classical Gompertz model and Logistic model were good at the temperature of 10, 15, 20, 25, 30, 35, 40, 45℃ and RH 40%, 60%, 80%. After F test and t test of growth curve during 24 samples, Gompertz model has been proved as the most available model with 100% acceptance by t test and 87.5% acceptance by F test. The secondary growth model- temperature predictive model was established too and the data processing of the model has shown that the minimum and maximum growth temperature of A. flavus at 40%, 60% and 80% are 3.78, 55.09 ℃; 8.83, 47.70℃ and 3.70, 53.69℃, respectively. It showed that this model is acceptable by comparison of experimental data and simulation results under controlled laboratory conditionsOrthogonal design and ELISA method were used to determine the content of aflatoxin B₁ in wheat. The factors which influenced the content of aflatoxin are: relative humidity > temperature > time. At the storage condition of 30 ℃ and RH 80%, the content of AFB₁ in wheat was relative high and at 40% RH, the content of AFB₁ in wheat didn't change with temperature and time.The risk assessment and orientation of AFB₁ in wheat were discussed too. Meanwhile, the simulations of model data, factors of metabolizing mycotoxins of Aspergillus flavus were analyzed. The risk analysis is conducted exclusively for adverse health effects caused by AFB], contaminants frequently found in wheat. It follows the concept of hazard identification, exposure assessment, dose-response assenssment and risk characterization.