The effect of fermentation treatment on the surface morphology, crystal structure, molecular weight, chain length distribution, and physicochemical properties of corn starch was investigated using natural fermentation of corn ballast. The amylose content in corn ballast starch reduced at first after natural fermentation, then grew, following the same trend as solubility. There were certain erosion marks on the surfaces of fermented corn ballast starch granules. The crystalline structure of corn ballast starch remained the same, i.e., a typical A-type crystalline structure, at different fermentation times; however, the intensities of diffraction peaks were different. The weight-average molecular weight of starch first increased and then decreased after fermentation. The content of low-molecular-weight starch (peak 3) decreased from 25.59 to 24.7% and then increased to 25.76%, while the content of high-molecular-weight starch (peak 1) increased from 51.45 to 53.26%, and then decreased to 52.52%. The fermentation time showed a negative correlation with the viscosity of starch, and the pasting temperature first increased, and then decreased. Natural fermentation can be used as a technical means to produce corn starch products as a result of the experiments' findings, and future experiments will detect and analyze the bacterial structure of corn fermentation broth in order to better understand the molecular mechanism of natural fermentation affecting the structure and physicochemical properties of corn starch.

The aim of this study was to investigate the influence of microwave drying on the protein quality of japonica sorghum following an intermittent drying test. Using label-free technology and liquid chromatography-tandem mass spectrometry for proteomic analysis, the effects of microwave drying on sorghum differential protein expression, functional classification, and metabolic pathways were analyzed at the molecular level. After sorghum was dried using a microwave, 85 differential proteins were identified. Among them, 51 showed up-regulated expression while 34 had down-regulated expression. The up-regulation and down-regulation of differential protein expressions significantly changed them, and proteins with larger up-regulated and downregulated expressions were postulated to affect biological and metabolic processes of sorghum during subsequent processing. Differential proteins were significantly (P ˂ 0.01) involved in metabolic pathways, such as carbon metabolism, glycolysis/ gluconeogenesis, carbon fixation in photosynthetic organisms, biosynthesis of amino acids, amino sugar and nucleotide sugar metabolism, and the TCA cycle. For the protein interaction network, glyceraldehyde-3-phosphate dehydrogenase of the downregulated proteins was postulated to be the key factor affecting the entire metabolic system or signal transduction pathway. Up-regulated proteins, including phosphoglycerate mutase and phosphopyruvate hydratase, as well as down-regulated proteins such as glyceraldehyde-3-phosphate dehydrogenase and fructose-bisphosphate aldolase, not only directly or indirectly affected a variety of metabolic processes, but were specifically closely related to glycolysis and glycometabolism. Overall, this study showed that among the related metabolic pathways, differential protein changes in glycometabolism pathways may have the greatest impact on metabolic processes. The research results discussed herein can provide theoretical support for the industrial application of microwave drying and deep processing of sorghum.