Screening high-enzyme-producing strains from fermented rice slurry to enhance amylose content and remodel starch structure in rice noodles.

The modulation of rice starch molecular structure and amylose content by microbial fermentation during rice noodle production remains unclear. In this study, crucial enzymes were identified and high enzyme-producing strains were screened from six traditional fermentation regions. Single and mixed-strain fermentations were conducted to assess their impacts on starch molecular structure and amylose content. α-amylase (α-AL) and debranching enzyme (DBE) activities were positively correlated with amylose levels. Co-fermentation with Lactobacillus rhamnosus, Lactococcus cremoris, and Saccharomyces cerevisiae enhanced α-AL and DBE activities, increasing amylose content by 13.56 %, with DBE exerting a stronger influence. Synergistic enzymatic hydrolysis cleaved α-1,4- and α-1,6-glycosidic bonds, preferentially breaking B3 long chains, enriching A chains, causing a decrease in branching degree, molecular weight, and particle size. Structural remodeling reduced rapidly digestible starch (RDS) by 6.02 % and increased resistant starch (RS) by 6.99 %. This study shows microbial enzyme-mediated starch restructuring enhances rice-based products' texture and nutritional profile.