Effect of the combined addition of hyaluronic acid and gellan gum on the physicochemical and digestive properties of tofu.

The aim of this study was to increase the quality of glucono-δ-lactone (GDL)-coagulated tofu by incorporating microbial polysaccharides. The effects of different concentrations (0.1 %, 0.2 %, 0.3 %) of hyaluronic acid (HA) and a fixed concentration (0.2 %) of low-acyl gellan gum (LAG) on the textural and digestive properties of tofu were investigated. Polysaccharide addition significantly enhanced tofu's texture; notably, the HA and LAG synergistically improved gel strength and water retention. Microstructural analysis revealed that HA filled the gel matrix and that LAG facilitated a coral-like structure. The LF-NMR and FTIR analyses indicated changes in water distribution and protein secondary structure, while XRD and XPS showed that the polysaccharides promoted protein aggregation resulting in a more stable tofu structure. In vitro digestion experiments demonstrated that although the digestibility of polysaccharide-enriched tofu was lower than that of nonenriched tofu, the amino acid content after digestion was higher. These properties positively influenced the satiety responses while maintaining the tofu's original nutritional value. Additionally, the addition of polysaccharides did not significantly affect the storage stability of tofu. In conclusion, the incorporation of HA and LAG significantly improved the quality of GDL-coagulated tofu, providing a theoretical basis for applying this technique in the food industry.