Study On The Growth,Succession Laws Of Mold And The Quality Of Mildew In Stored Paddy Rice

Rice as a kind of grain reserves,the storage security of rice is closely related to the national economy and people’s livelihood.The research focuses on mold that is an important risk factor affecting the safety of rice storage,investigate the influence of mold growth,succession and mold growth on the quality of rice under simulated conditions and real warehouse environment.Under the condition of simulated local high temperature and high humidity storage,the amount of mold in rice increased with the storage period,and the amount of mold increased with the increase of moisture content and storage temperature.In the stored rice mainly separate to ten kinds of mold,in which that The field of mold comprises Fusarium graminearum,Cladosporium cladosporioides,the storage of mold for Aspergillus niger,Aspergillus versicolor,Aspergillus albicans,Penicillium griseofulvum,Aspergillus sydowii,Aspergillus glaucus,Penicillium sp,Aspergillus flavus.With the increase of storage time,the mold flora structure changed.In general,the dominant mold in the pre-storage,middle and late stage of rice is the Fusarium graminearum,Aspergillus glaucus,Aspergillus albicans,and the increase of initial moisture content and storage temperature will accelerate the area system of mold succession from field to storage.The amount of mold in rice is at the level of safety standard during the real warehouse storage process.After storage for 3 months,the average amount of mold in rice was reduced from 4.7×10~4cfu/g to 1.9×10~3cfu/g,while the average number of mold increased slightly to 3.0×10~3cfu/g at 6 months.In addition to the initial sample,the amount of mold in the rice was lower than 10~5cfu/g,which was within the controllable safety range.During storage,the microflora structure of mold in the grain was changed.The Fusarium graminearum is the dominant mold in the original rice.After three months of storage,the dominant mold in rice were mainly Aspergillus glaucus.After six months of storage,the main dominant mold in the rice were Penicillium,Aspergillus flavus and Aspergillus albicans.The value of fatty acid is the main index to test whether rice can be safely stored.The simulation warehouse experiment shows that the value of the fatty acid is related to the storage temperature and the initial moisture content of rice.Lower moisture content of rice fatty acid value less affected by temperature,under high moisture content of rice increase storage temperature will accelerate the rise of fatty acid value,simply raising moisture storage will also speed up the change of fatty acid value significantly.In the three simulated storage temperatures,the storaged rice that is 15.5%of the moisture content was all more than37mgKOH/100g after 120 days,it is too severe to be stored.In the real warehouse storage process,the storage conditions are well controlled.The value of the fatty acid in the paddy being changed slowly,and the rice in different positions were slightly different in the value of fatty acids.However,the average fatty acid value was 24.4 mgKOH/100g after 6 months of storage,and the every sample points were lower than 30mgKOH/100g,which were still at the appropriate level.The mildew of rice will change the nutritional composition of rice.The volatile components and contents of the samples which with a large amount of mold in simulated storage were different from those of normal samples in the real warehouse storage.In the simulated storage process,the contents of volatile components of rice were the highest,and the change was the largest during the storage period.In the aldehydes,the content that the high content of the characteristic aldehydes showed a decreasing trend,and the decrease of the characteristic aldehydes which is the high water content rice was larger,and the influence of different temperature conditions was not obvious.Different from the simulated storage,the variety and content of flavor ester of rice in real warehouse storage are more obvious.There were only two types of flavor esters of rice in real warehouse storage.After three months of storage,the types and contents of esters increased significantly,but the contents of contents of esters were significantly reduced at six months.In this paper,the results showed that the mold number in the rice of moisture less than 13.5%under the condition of warehouse stroed which is the safe moisture is lower than the safety standards,can safely stored,but the mould of high moisture rice to grow rapidly,and cause grain temperature rise,the quality of rice rapidly deterioration.Therefore,it is necessary to pay close attention to the whole grain situation in rice storage,and the local moisture rise and local temperature rise should be taken measures to reduce water and temperature as early as possible,so as to prevent the growth of mold storage and ensure the safe storage of whole grain.