Study On Changes Of Fungi And Main Mycotoxins In Wheat During Storage

Wheat has strong hygroscopic characteristics and a long after-ripening period,which inevitably results in the presence of a large number of fungi during storage.These fungi can grow and reproduce rapidly under suitable storage conditions,potentially leading to the production of mycotoxins that pose a risk to the safety of wheat storage.In this study,we analyzed changes in fungi and main mycotoxins during the storage of head blight-infected wheat,and constructed an early warning model for mycotoxin presence in wheat storage to provide a reference for predicting and detecting mycotoxins in wheat storage.We analyzed changes in wheat fungi and major mycotoxins,such as DON and its derivatives 3-Ac-DON and 15-Ac-DON,under different storage conditions,including temperature,moisture levels,initial mycotoxin content,and tonnage of grain stored in a warehouse under naturally occurring scab-infected wheat.Based on a Logistic regression model,we developed an early warning system for the occurrence of mycotoxins during wheat storage.Our study results are as follows:(1)In simulated storage conditions,we observed that more pronounced changes in mycoflora were associated with significant changes in mycotoxin production.Wheat was stored under different temperatures,moisture levels,and initial mycotoxin content,resulting in significant variation in mycotoxin levels.The optimal temperature for Fusarium to produce mycotoxins was found to be 25℃.Due to intense fungal competition during early high-temperature storage,there was a wide fluctuation in DON content.Storage pests had a significant impact on DON content at 30℃.Under high moisture conditions in wheat storage systems,there is intense fungal competition,resulting in significant fluctuations in DON content.When stored at 12%moisture content,stress-induced production of DON by Fusarium during the later stage of storage leads to a significant increase in DON levels.Fusarium competition was found to be low in wheat with low DON content,while the conversion of DON was complex in wheat with high DON content.(2)During storage of tons of grain in a warehouse under varying mycotoxin content and storage conditions,we observed a similar trend in mycotoxin changes in wheat,with significant differences in the timing of mycotoxin changes.When stored indoors at a constant temperature of 25℃,fungal competition was found to be more intense,resulting in significant differences in mycotoxin changes compared to natural storage conditions.During constant temperature storage,temperature,humidity,and CO2 levels increased and were significantly influenced by grain storage pests.Under natural storage conditions,temperature,humidity,and CO2 levels fluctuated with environmental changes.(3)A database was established based on environmental parameters and mycotoxin content changes during wheat storage,and a suitable warning model equation was derived(the specific equation is:Logit P=ln(P/1-P)=52.145-430.908aw+1.552T+308.509aw2-0.114T2-2.409awT-0.031time).Accuracy is 83.05%,indicating good prediction performance.This model was then verified and optimized by simulating grain storage in a 240-ton storage warehouse of a large grain depot.Based on the optimized Logistic model,a change prediction and early warning system for mycotoxin content changes in wheat storage was developed to provide scientific and technical support for the safe storage of wheat.In conclusion,mycotoxin changes during wheat storage were significantly influenced by changes in mycoflora.Greater fluctuations in mycotoxin content were observed when there were more pronounced changes in mycoflora.The optimal temperature for Fusarium to produce mycotoxins was found to be 25℃.Storage of wheat with 12%moisture content may lead to stress-induced production of Fusarium mycotoxins,while wheat with low initial mycotoxin levels is more suitable for storage.During ton storehouse storage,we observed a similar trend in mycotoxin changes,with significant influence from initial mycotoxin levels,storage temperature and humidity,and grain storage pest infestation.Furthermore,the Logistic model was effective in predicting mycotoxin changes during the wheat storage process.