Xiaomin Guo, Muyao Lin, Jiaqi Liu, Haobo Chu, Mokhele Matsomoli Roslina, Nan Zheng, Xun Li, Xun Li, Yuyi Wang, Bo Nan, Xiujuan Wang, Chunhong Piao, Yuhua Wang, Xia Li, Xia Li
Based on the previously screened high-performance strain Lactobacillus LP707, this study systematically investigated the effects of its co-fermentation with yeast on properties of millet starch. By comparing starch samples from unfermented, yeast-only fermented, Lactobacillus-only fermented and co-fermented treatments, it was found that co-fermentation reduced the amylose content of millet starch to 17.45% and shifted the molecular weight distribution toward lower values. Scanning electron microscopy revealed more pronounced surface erosion features on the co-fermented starch granules. X-ray diffraction and Fourier-transform infrared spectroscopy confirmed that co-fermentation did not alter the A-type crystalline pattern of starch; however, the short-range ordered structure ratio (1.45), relative crystallinity (20.78%), and gelatinization enthalpy (7.32 J/g) were significantly reduced, indicating dissociation of ordered structures. Pasting property analysis showed that the final viscosity and setback value of co-fermented starch decreased significantly. Low-field nuclear magnetic resonance analysis of water distribution indicated an increased proportion of free water with reduced mobility in the co-fermented starch gel. In vitro digestion confirmed higher hydrolysis rates and increased rapidly digestible starch content in co-fermented starch. In summary, co-fermentation with Lactobacillus LP707 and yeast more effectively modified properties of millet starch, providing a theoretical foundation for targeted functional improvement through microbial co-fermentation technology.