Study On Prevention And Control Of Aspergillus Flavus Contamination In Maize During Storage Period With Ar-tumerone

Aspergillus flavus is a common saprophytic pathogenic fungus with serious harm.The secondary metabolite aflatoxin produced by Aspergillus flavus is easy to contaminate food and is one of the important risk factors affecting food safety.Aflatoxin can pollute agricultural products in the process of harvesting,processing,storage and transportation,and accumulate in the human body through the food chain.Aflatoxin may cause hepatotoxicity,kidney toxicity,and even cancer.Maize is a common staple food in daily life.Because of its high carbohydrate and water content,it is easy to be contaminated by Aspergillus fl avus and aflatoxin,which leads to quality degradation and safety hazard.Therefore,it is very important to find effective methods to control the pollution of Aspergillus flavus and aflatoxin.Based on our previous research,this dissertation mainly introduced the effect and mechanism of Ar-tumerone,which is the main active component of turmeric essential oil,on the growth of Aspergillus flavus and the accumulation of aflatoxin.And the effectiveness of the application of Ar-tumerone in preventing maize from being contaminated by Aspergillus flavus during storage was expounded.The first chapter of this paper introduced the harm of Aspergillus flavus and aflatoxin,the present situation of maize Aspergillus flavus pollution,the main prevention and control methods and the related research progress of aromatic ginger flavonoids,etc.,which provided the relevant ideas and foundation for the experimental design of the subject.The second chapter of this paper was the synthesis of Ar-tumerone,the main active component of turmeric essential oil.The chemical synthesis could obtain pure Ar-tumerone in good yields,effectively solved the problem that the yield of Ar-tumerone was affected by turmeric species and origin;the optimization of reaction conditions reduced the equipment requirements,simplified the synthesis method and improved the reaction yield.The third chapter of this paper was the study on the antibacterial and antitoxic effect of Ar-tumerone on Aspergillus flavus.It was found that Ar-tumerone had dose-dependent inhibitory effect on Aspergillus flavus growth and aflatoxin accumulation.The higher the concentration of Ar-tumerone,the better the inhibitory effect was.50.00μg/mL Ar-tumerone could 100.00%inhibit the Aspergillus flavus growth,spore germination,mycelium biomass and aflatoxin accumulation within 7 days.25.00μg/mL Ar-tumerone could inhibit 83.50%spore germination and 72.88%AFB₁ accumulation on the surface of maize for short-term storage under high temperature and high humidity.In addition,the method of pre-column derivatization-high performance liquid chromatography-fluorescence detector was optimized and validated in this chapter.The optimized method has low detection limit,high sensitivity and low equipment requirements,and could realize the detection of low-dose aflatoxin.The fourth chapter of this study provided the antibacterial and antitoxic mechanism of Ar-tumerone at the molecular level for the first time.2,018 differentially expressed genes（DEGs）such as catA,ppoC,erg7,erg6 and aflO related to the A.flavus growth and aflatoxin product were significantly downregulated including 45 DEGs were 100.00%suppressed.In addition,the related mechanism of action was demonstrated through the fungal cell-related experimental reasoning.In the fifth chapter,a method of the application of Ar-tumerone in maize storage was designed,and the optimal condition of resistance to Aspergillus flavus pollution during maize storage were 0.940 aw,400μg/mL Ar-tumerone,16 ℃,which were determined by single factor and orthogonal experiments.The fuzzy matrix was used to compare the sensory changes of maize stored under the best conditions for 21 days and found that there was no significant difference in maize quality,except for the slight smell of Ar-tumerone,which indicated that Ar-tumerone had the potential of antifungal application in food.