Digestibility of indica rice and structural changes of rice starch during fermentation by Lactobacillus plantarum

Fermentation technology is a useful tool to modifying starch, and the relationship between starch structure and digestibility is a crucial parameter that affects fermentation technology. In this study, the changes in digestibility and starch structure of indica rice during fermentation by Lactobacillus plantarum were investigated. The relationship between digestibility and the changes in starch composition, amylose content, chain length distribution of amylopectin, short-range ordered structure, and relative crystallinity was analyzed. The results showed that during the fermentation of indica rice by L. plantarum, the glycemic index (GI) of the indica rice decreased, and after 60 h of fermentation, the GI of indica rice decreased from 82.88 to 74.53. Additionally, the contents of slowly digestible starch (SDS) and resistant starch (RS) increased. Furthermore, the proportion of short chain of amylopectin increased, which facilitated the intermolecular interaction of short chain to form a compact and orderly structure. This led to an increase in short-range ordered structure and relative crystallinity of indica rice starch. These structural changes promoted the stability of starch structure, resulting in a decrease in rice digestibility. This work has significant implications for the development of low-GI rice and rice-based foods.