Study On Variation Of Maize Storage Quality Based On Grain Ecology

China’s annual grain loss is very alarming,in the production,storage,transportation,processing,consumption and other aspects of the loss,of which storage is the key link.Because the proportion of storage time in the whole chain of grain is the largest,and it is easily affected by storage environment,warehouse facilities,microorganisms,pests,grain itself and technical management measures,resulting in grain loss.In addition,compared with the traditional grain situation detection system,it is difficult to obtain the state of grain storage quality in real time.However,the current prediction model of grain storage quality is mainly constructed on the premise of ideal conditions,and less influencing factors are considered.Therefore,this study intends to use the theory of grain storage ecology to study the changes of the main storage quality of maize under the influence of different abiotic factors(temperature,humidity,water,etc.).The reference map of corn quality was drawn to provide theoretical guidance for scientific grain storage.In this thesis,the newly harvested corn with initial moisture content of 15.7%w.b.was used as raw material,and the corn samples with three moisture gradiants of 13.04%,14.03%and 14.99%w.b were cleaned by removing impurities and dried naturally.The samples were sealed and placed in a constant temperature and humidity environment with temperature(20℃,25℃,30℃)and relative humidity(65%,70%,75%RH)to carry out a three-factor and three-level response surface storage experiment.The key quality indicators were detected by regular sampling to explore the quality changes of corn during storage.(1)The overall change of maize moisture content showed a fluctuating trend,first increasing and then decreasing.The higher the temperature and humidity of the storage environment,the greater the variation range;And the higher the relative humidity,the greater the absolute value of change,and the greater the equilibrium rate of water content.The increase rate of corn fatty acid value was positively correlated with storage time,moisture content,temperature and humidity,but the change of corn fatty acid value was slow in the early storage stage.Corn bulk density was negatively correlated with storage time,temperature and humidity.The germination rate of maize stored at different temperature and humidity showed a decreasing trend with the extension of storage time,and the germination rate decreased faster with the increase of temperature and humidity.The change rate and range of maize appearance quality were positively correlated with storage temperature,humidity and time,that is,the darker the maize surface color L*was,the more difficult it was to maintain the original color,and the faster the decrease rate of b*value was.The micro structure surface of corn starch granules changed from smooth and flat to sunken and coarseness,with edges and corners.The arrangement gradually changed from tight structure to sparse and disordered,and the appearance of corn grains changed from smooth and neat to concave and convex folds..(2)According to the analysis of LS/T 6132-2018《Detection spore Counting Method of Stored Grain Fungi for Grain and Oil Inspection》,the number of fungal spores in maize was significantly correlated with storage time,temperature and humidity.The corn with a moisture content of 13.04%w.b.was stored in different temperature and humidity environments,all of which were in a critical state and could be stored safely.Corn with moisture content of 14.03%w.b.can be safely stored at 20℃(65%RH)for 280 d,and when the humidity rises to 75%RH,the safe storage period of corn is 180 d;After storage at 25℃ and 30℃ for 80 d,the number of fungal spores exceeded the standard.and long-term safe storage could not be achieved.At 20℃ and 25℃,it can be safely stored for 180 d and 40 d,respectively.Corn with moisture content of 13.04%w.b.was stored under different temperature and humidity conditions,and corn with moisture content of 14%w.b.was stored at 20℃ and 65%RH.The detection amount of aflatoxin B1 was within the limit standard,and other storage conditions exceeded the limit standard.The increase and rise rate of zearalenone content were significantly positively correlated with storage time,temperature and humidity,but there was no significant change in zearalenone content during short-term storage,and its content was within the safe range.The content of corn vomitoxin under different storage conditions increased slightly in the early stage of storage,and the rate of change increased with the increase of storage moisture content and temperature and humidity.Among them,the corn with water content of 14.99%w.b.has the highest rate of increase at 30℃ and 70%RH,that is,when the storage time is 100 d,its value exceeds the limit standard by more than ten times.(3)Five response values,including fatty acid value,spore number,aflatoxin B1,zarealenone and vomitoxin,which changed significantly during corn storage were selected for multiple quadratic regression analysis.The coefficients of determination of the established regression model were 0.9512,0.9633,0.7408,0.7516 and 0.8991.The quality reference plots of multi-factor coupling-changes of each index,fatty acid value-spore number,fatty acid value-aflatoxin B1,fatty acid value-zetenone,fatty acid value-vomitoxin were drawn.After verification analysis,it is proved that the chart can be applied in practice,and can provide data reference for corn storage and processing.The quality index changes under certain storage conditions can be directly checked by referring to the quality reference figure,so as to determine the safe storage conditions of corn.For example,by referring to the quality reference figure of fatty acid value-spore number,when the moisture content of corn is 13.5%and the relative humidity of storage is 70%,the storage temperature of corn should be controlled below 27℃ to ensure the safe storage of corn for 360 d.In summary,this paper takes corn as the research object,explores the change rule of corn quality index in the storage process of different abiotic factors,and draws the quality reference chart of key quality index,which can directly and quickly reflect the quality and state of corn.According to the reference figure,the storage quality changes of corn can be predicted,and the storage abiotic factors can be regulated to realize the storage of corn quality and realize the green grain storage.