Study on the changes of the structure and physiochemical properties of millet starch induced by Pediococcus acidilactici fermentation.

Millet starch is one of the most dominant components of millet and is essential to understand how fermentation can be applied to improve the quality of traditional millet starch-based foods. Fermentation has long been an important method for cereal food processing and remains an effective approach for starch modification. This study aimed to investigate the impact of probiotic fermentation (Pediococcus acidilactici) on the structural and physicochemical properties of millet starch. The results demonstrated that fermentation reduced pH from 6.45 to 3.16-3.46 and bacterial viability from 1.08 × 10 CFU/mL to 1.25 × 10 CFU/mL over 48 h, attributed to organic acid production. After 24 h of fermentation, the amylose content in millet increased to 21.61 %, compared to 20.60 % in unfermented samples. Microscopic analysis showed that the surface of the starch granules was eroded and the granule size changed dynamically due to fermentation. Multi-scale structural characterization indicated a significant increase in relative crystallinity (24.05-26.08 %), while the crystal structure remained A-type. Furthermore, analyses of pasting, thermodynamic, and hydration properties showed that fermentation led to a decrease in peak viscosity, disintegration value, and hydration capacity, suggesting a positive influence on the starch's pasting behavior. These findings demonstrate that fermentation with P. acidilactici is an effective strategy for modifying millet starch and could significantly enhance the quality of starchy foods.