Study On Warning Of AFB₁ Contamination In Stored Maize By Monitoring Catalase Activity

It is easy to contaminate aflatoxin B₁（AFB₁）for corn during storage.Early warning of AFB₁ production is the key to preventing contamination of AFB₁.In this paper,the relationship between the changes of catalase activity and the increase of AFB₁ content was studied by simulating the mildew process under different storage conditions of maize.As well as the changes in the activity of catalase before and after the increase of AFB₁ content,it is expected that AFB₁ can be early predicted by monitoring the change of catalase activity.The increase of catalase activity during corn storage was mainly due to the growth of mycelium and the production of spores,and the increase of catalase activity caused by mycelial growth was dominant.The mycelial activity of Aspergillus flavus was the highest,reaching 3.0 × 104 U/ g,and the mycelium activity of Aspergillus fumigatus was the smallest,only 1.0 × 103 U/ g.When the storage temperature increased from 20℃ to 35℃,the content of catalase was increased by 1.5 1.8 times and at the same time the content of AFB₁ increased 80 times,5 times and-2 times respectively.The effect of increasing or decreasing the unit temperature on the change of catalase activity value is more uniform,but the effect on AFB₁ content is quite different.When the storage temperature is relatively low,the production of AFB₁ is more sensitive to changes in temperature.The increase of water content in maize affects the growth rate of catalase activity and the change of AFB₁ content during storage.When the moisture content of maize is relatively low,increasing the same moisture content has a greater effect on the increase of catalase activity.Under the same storage environment,the difference of the initial amount did not affect the changes of catalase activity and AFB₁ during corn storage,and only affected the value at the same storage period.The relationship between the catalase activity and AFB₁ is corresponding to the quadratic function.When the growth of differentmolds is dominant,the relationship between the activity of hydrogen peroxide and the quadratic function of AFB₁ is quite different.The increase in the activity of catalase during corn storage was always earlier than that of AFB₁ for 7 to 35 days.By analyzing the changes of catalase activity before the AFB₁ content increased to 20 μg/kg,we found that the catalase activity increased linearly with time.And different AFB₁ produce rates correspond to different catalase activity growth.It indicates that AFB₁ production is highly sensitive and reliable based on changes of catalase activity.It is possible to significantly delay the production of AFB₁ and decrease the rate of increase of catalase activity in the high-moisture corn storage period.When the monitoring showed no increase in the activity of catalase,the AFB₁ content in maize was no longer increased.And the increased duration of catalase activity may be used as the latest point of time for maize to take ventilatory precipitation.