Differential Effects of Pre-Fermentation with Different Lactic Acid Bacteria Strains on the Structure, Functionality, and Flavor of Semi-Dry Milled Glutinous Rice Flour

This study selected three lactic acid bacteria strains (Lactiplantibacillus plantarum CGMCC 1.12974, Limosilactobacillus fermentum CICC 22704, and Lactobacillus acidophilus CICC 22162) to pre-ferment brown and polished glutinous rice grains followed by semi-dry milling, aiming to systematically compare the differential effects of various strain treatments on the structure, functionality, and flavor of glutinous rice flour. Pre-fermentation decreased protein content (11.23–20.80% in polished flour, 0.14–2.45% in brown flour), enriched γ-aminobutyric acid (GABA, up to 6.94 mg/100 g), increased relative crystallinity and gelatinization enthalpy, and altered hydration properties. Dumplings from fermented flours showed higher soup transmittance (up to 44.93% in the brown rice group), reduced hardness (24.82–67.32%) and chewiness, and improved cohesiveness and resilience. Volatile profiles shifted towards higher acids and esters and lower alcohols, aldehydes and ketones, with strain-specific features. Redundancy analysis confirmed that starch became the dominant texture-determining factor after fermentation. Among the three strains, Lp. plantarum CGMCC 1.12974 exhibited the best improvement for most quality attributes. In conclusion, pre-fermentation of rice grains effectively enhances whiteness, GABA content, textural softness, and flavor diversity of semi-dry milled glutinous rice flours.