Effects of fermentation on the structure and physical properties of glutinous proso millet starch

This study investigated the effects of spontaneous and Lactobacillus plantarum (LP) fermentation on structure glutinous proso millet starch (GPM) and physical properties. In order to explore starch changes by fermentation for quality regulation of fermented food glutinous proso millet and improve properties of modified GPM starch products. The molecular weight, amylopectin chain length distribution, morphological properties, short-range ordered structure, and crystal structure of GPM starch were analyzed. Results showed that compared with the non-fermented GPM starch, amylose content of spontaneous and LP-fermented GPM starch increased then decreased, with the latter decreasing faster. There were no changes in the Type A structures of spontaneous fermented, LP-fermented, and non-fermented GPM starch. After 24 h of LP fermentation, higher water swelling power, and lower GPM starch solubility were obtained compared to non-fermentation and spontaneous fermentation. The decrease in pasting properties and thermal properties while increasing GPM starch properties was shown after fermentation compared to non-fermentation experiments. Besides, LP fermentation showed faster changes of these properties than spontaneous fermentation. In conclusion, our findings showed that fermentation could improve GPM starch properties, benefiting fermented GPM products and as a modification method for GPM starch. Especially, LP fermentation was more effective than spontaneous fermentation.