# Combined Effects of Lactic Acid Bacteria Fermentation and Physical Milling on Physicochemical Properties of Glutinous Rice Flour and Texture of Glutinous Dumplings

## TL;DR

This study shows how combining lactic acid bacteria fermentation with different milling methods improves the quality and texture of glutinous rice flour and dumplings.

## Contribution

The novel contribution is the combined use of LAB fermentation and physical milling to enhance the functional properties of glutinous rice flour.

## Key findings

- Fermentation with dry or semi-dry milling improved whiteness and increased GABA, phenols, and flavonoids in glutinous rice flour.
- Fermented flour showed higher peak viscosity and better texture in dumplings, especially when using Lactiplantibacillus plantarum.
- Peak viscosity and breakdown viscosity were key factors for better dumpling texture, while damaged starch and protein were negative factors.

## Abstract

This study investigated the combined effects of lactic acid bacteria (LAB) fermentation and different milling methods (wet, semi-dry, and dry) on the physicochemical properties of glutinous rice flour (GRF) and the texture of the final product. A systematic analysis of rice samples treated with three LAB strains (Lactiplantibacillus plantarum CGMCC 1.12974, Limosilactobacillus fermentum CICC 22704, and Lactobacillus acidophilus CICC 22162) revealed that fermentation pretreatment created favorable conditions for subsequent physical milling by degrading the protein network and modifying the starch structure. The results demonstrated that fermentation combined with dry or semi-dry milling significantly improved the whiteness of GRF and the contents of γ-aminobutyric acid (GABA), total phenols, and total flavonoids, while reducing the contents of damaged starch (except in samples fermented with Lb. acidophilus) and protein by 2.91–12.43% and 17.80–32.09%, respectively. The functional properties of the GRF were also optimized: fermented flour exhibited higher peak viscosity, lower gelatinization temperature, and higher gelatinization enthalpy. Texture profile analysis revealed that glutinous dumplings prepared from fermented dry/semi-dry milled GRF, particularly those fermented with Lp. plantarum, showed significantly reduced hardness and chewiness, along with significantly improved cohesiveness and resilience. Consequently, their texture approximated that of high-standard wet-milled products. Correlation analysis based on the top ten discriminative features selected by random forest identified peak viscosity and breakdown viscosity as the most important positive factors associated with superior texture (high resilience, high cohesiveness, and low hardness), whereas damaged starch content and protein content were key negative correlates. In summary, this study confirms that the combination of fermentation and milling exerts a beneficial influence on the functional quality of GRF.