臭氧降解玉米中黄曲霉毒素B_1效果及降解动力学研究

Efficiency and Kinetics of Ozone Degradation of Aflatoxin B_1 in Corn

玉米是我国重要的食品和饲料原料,当收获、加工和储藏等措施不当时,可能会造成黄曲霉毒素B1(aflatoxin B1,AFB1)污染玉米这一突出问题,AFB1已被国际癌症机构定为1级致癌物。尽管目前已建立了一些物理、化学和生物降解AFB1的方法,但高效、安全、经济的绿色降解方法仍很少。本研究以AFB1污染的玉米为试样,研究臭氧对玉米中AFB1的降解效果。结果表明:AFB1降解率随着臭氧质量浓度的增加和处理时间的延长而显著提高;当水分质量分数为20.37%的玉米经90mg/L的臭氧处理40 min后,AFB1含量由77.6 μg/kg降低到21.42 μg/kg,降解率达72.4%。臭氧降解AFB1的动力学模拟结果表明,臭氧降解AFB1符合一级动力学模型。玉米中AFB1降解速率常数按以下次序递减:k90 mg/L>k65 mg/L>k40mg/L。实验得到臭氧降解AFB1的动力学方程、反应速率常数、决定系数和半衰期,为最优地控制臭氧降解AFB1的反应条件奠定了理论和实践基础,也为臭氧降解AFB1污染玉米的应用提供了技术保障。

As an important ingredient in feed and food, corn is prone to being contaminated by AFB1 during harvesting, processing and storage. Although several physical, chemical and biological protocols have been established to degrade AFB1, efficient, safe, economical and environmentally friendly methods remain scarce. In this study, the efficiency of ozone degradation of AFB1 in corn was explored. The results showed that with increasing ozone concentration and treatment time, the degradation rates of AFs in corn were evidently elevated. The AFB1 contents in corn with a moisture content of 20.37% plummeted from 77.6 μg/kg to 21.42 μg/kg after 40 min of treatment with 90 mg/L ozone, viz., the degradation rate was 72.4%. The degradation of AFs in different raw materials by ozone followed first order kinetics. The degradation rate constants of AFBm in corn followed the descending order of k90 mg/L〉k65 mg/L〉k40mg/L Kinetics parameters, such as kinetic equations, reaction rate constants, correlation coefficients and half-life periods, provided valuable evidence for controlling ozonation under optimum conditions and for clarifying the influence of ozonation on AFB1 in corn. Hence, the findings allow feasible application of ozonation in degrading AFB1 in corn.