Relationship Of Main Fungal Growth And Mycotoxin Formation With CO₂ Production During The Grain Storage

This report mainly studies on the relationship of main fungal growth and mycotoxin formation with CO2 production during the grain storage, and explores for the correlation between the changes of CO2 production rate and mycotoxin content. The results show that CO2 gas detection method can significantly predict in the possibility of mold growth and toxin production, and guarantee the safety of stored grain. Difference of producing CO2 by Different populations of fungi is the reflection of their own metabolic properties, as well as by the effects of temperature and moisture content of the grain. In the early grain storage, mold grows in the spores season, CO2 levels are relatively low, when a significant increasing of CO2 release rate happens in the fungal hyphae growing season. There is a significant correlation between the changes of CO2 release rate and the amount of mold and mycotoxin concentration.Aspergillus flavus is the major fungal species producing AFB1 in corn. Growing and toxin production of Aspergillus flavus are closely related with the temperature, relative humidity and moisture content during corn storage. Growth rate of wet mold like Aspergillus flavus and Penicillium is 4.6 times faster than that of dry mold as Aspergillus glaucus in the environment more than 0.8 water activity. The original dominant fungal community is not the main factor affecting AFB1 production in corn. Corn infected by different types of dominant mold can produce AFB1 in one month, when the yield of AFB1 in Aspergillus flavus advanced group is 3 to 7 times than the others. The growth rate of fungi has a little effect on AFB1 production, but will affect the magnitude of CO2 production,and the regularity of CO2 production rate does not change. Increasing storage temperature and grain moisture content can shorten the trend of CO2 release rate and AFB1 concentration increasing. The time of CO2 release rate elevating usually is more than 7d earlier than that of AFB1 concentration.At high temperatures, the changes of CO2 release rate in rice have good predictability on OTA production. under 25 ℃, CO2 release rate began to increase significantly(P <0.05) in the first 21 d, and OTA concentrations increased significantly at first 28 d in the rice of 16.5% moisture. Under 30℃, CO2 release rate appears growth trend in 7d, while OTA concentrations rise phenomenon began to appear in 21 d. In toxigenic fungal infected low-moisture corn, OTA concentration level under 30 ℃is approximately double higher than that under 25 ℃. CO2 release rate increased in 14d(25℃) and 7d(30℃) respectively before the appearance of mycotoxin. Wheat is more vulnerable by Fusarium graminearum than corn and rice, and level of DON concentration is closely related to the growth areas and species of wheat. Changes of CO2 release rate exhibits a good prediction for the DON production.The likelihood of microbial growth and mycotoxin production can be predicted via monitoring the changes of CO2 content before the apparent mildew in wheat, corn and rice. Using the detection method of CO2 to warn the production of mycotoxin in grain, managers can make timely judgments and take effective measures to deal with moldy grain, providing strong protection of stored grain security.