准低温条件下不同含水量玉米储存品质和微观结构变化

玉米因富含营养物质、自身胚部大，易受到虫霉等侵染，造成其品质劣变，因此玉米保质保鲜储存具有一定的挑战，为此需要明晰玉米的储存品质规律与变化。以初始含水量分别为13.04%、14.03%、14.99%玉米为研究对象，以常温储藏环境(25℃)为对照研究在温度20℃准低温储存期间玉米的容重、脂肪酸值、发芽率、霉菌活动等品质与安全指标变化规律及玉米籽粒微观结构变化。实验结果表明：在20℃下，三个不同初始含水量的玉米的发芽率、脂肪酸值、容重较25℃储存环境下变化均较慢，均处于宜存范围。真菌孢子数随储存时间延长而急剧上升，且与玉米初始水分含量具有显著性相关，即14.99%的玉米储存至120d，真菌孢子数量级别已达到严重危害程度，13.04%、14.03%、14.99%玉米的安全储存期分别为180d、180d和100d。储存期间的玉米微观结构发生了渐变，即表面由平滑整齐变为凹凸褶皱，淀粉颗粒排列由结构紧密逐渐变为稀疏无序。由此可知，玉米在(准)低温储存条件下，储存时间和初始含水量是影响玉米储存品质和微观结构变化的主要因素。研究结果为实现玉米产后保质减损提供新的视角。

Study on Storage Quality Change and Microstructure of Maize with Different Moisture Content under Quasi-low Temperature

Corn is abundant in carbohydrate, protein, carbohydrates and other nutrients. However, because of its large embryo, it is easy to be infected by microorganisms and insects, which leads to the deterioration of corn quality. Therefore, the quality preservation and storage of corn is a challenge. So it is necessary to clarify the rule and change of corn storage quality. Corns with initial water content of 13.04%, 14.03% and 14.99% were taken as reasearch objects in this paper. During storage between 70% relative humidity and 20 ℃ (quasi-low temperature environment) , the changes laws of quality indexes such as bulk density, fatty acid value, germination rate, mold activity and microstructure of corn grain were studied emphatically. Otherwise changes of storage quality of corn at 70% relative humidity and 25 ℃ (room temperature environment) were compared. Therefore it can provide reference for safe storage of high-quality corn. The results demonstrated that the germination rate, fatty acid value and bulk density of corn under 20 ℃ were slower than those under 25 ℃. And they were in the suitable storage range in accordance with the national standard. The number of fungal spores increased sharply with the prolonged storage time. Meanwhile it showed significant correlation with the initial moisture content of corn. In other words, the number of fungal spores for corn under 14.99%w.b was stored for 120 d, and the safe storage periods of corn under 13.04%w.b, 14.03%w.b and 14.99%w.b were 180 d, 180 d and 100 d, respectively. The microstructure of corn kernel changed gradually during storage. It means the appearance changed from smooth and tidy to concave and convex folds. Furthermore, the arrangement of starch granules changed from tight structure to sparse and disordered structure. The main factors of corn quality and microstructure change were corn initial water content and storage time, during storage at quasi-low temperature environment. So the change laws of corn storage quality with different water content were explored, so as to provide new research perspective for maize post-harvest to reduce loss and guarantee qualtiy.