Abstract:The efficiency of traditional maize drying is low and the quality of dried maize kernel is not good. Maize will be damaged during processing. Natural drying, hot-air drying and hot-air-vacuum combined drying of maize kernel were carried out, and the mechanical properties and apparent morphology of maize kernel dried by three methods were investigated. The test results of mechanical properties showed that the maize kernel dried by 50℃ hot-air+45℃ vacuum had the largest deformation. In hot-air drying, the creep curve of maize kernel dried at 65℃ was the highest, and that of maize kernels dried at 75℃ was the lowest. Among three drying methods, the stress achieved by the stress relaxation curve of natural drying was the largest, and its value was 0.0455MPa. In compound drying, the stress achieved by the stress relaxation curve of 50℃ hot-air+65℃ vacuum was the largest, and its value was 0.0414MPa. The three-element Maxwell model could fit the stress relaxation test results well, and the coefficients of determination were all above 0.977. Both the storage modulus (G′) and loss modulus (G″) of maize kernel were increased with the increase of frequency. The storage modulus was greater than loss modulus, and the dominant position was occupied by elasticity. The elasticity of dried maize kernel was greater than its viscosity. The results of the apparent morphology test showed that the starch granules in maize kernels dried at high temperature were relatively drier and shriveled, while those in maize kernels dried at low temperature were rounder and plumper. At the same temperature, the starch granules dried by compound process were plumper than those dried by hot-air. The quality of the maize kernel dried by compound process was better. The maize kernel structure exhibited A-type crystalline pattern. The characteristic peaks of maize kernel dried by hot-air appeared at about 13.7°, 15.7°, 16.4°and 21.5°(2θ). Among them, single peaks appeared at 13.7° and 21.5°, and double peaks appeared at 15.7°and 16.4°. In compound drying, only 50℃ hot-air+55℃ vacuum and 50℃ hot-air+65℃ vacuum were basically the same as natural drying. Their characteristic maize peaks appeared at about 14.8°, 16.9°, 17.8°and 22.8°(2θ). The mechanical properties of maize kernel dried by hot-air-vacuum compound process could provide an experimental basis for the development of maize processing and storage related equipment.