Gellan gum regulated high-moisture extruded soy protein: Texture and structure

Single-material systems high-moisture extrudates have limitations regarding texture and digestibility; however, biphasic material systems can effectively regulate and improve the properties of the extrudates. This study subjected soy protein isolate (SPI) and gellan gum (GG) mixtures with varying mass ratios to high-moisture extrusion (HME), systematically characterizing the morphology, texture, structural characteristics, rheological behavior, digestive properties, and moisture properties of the extrudates. The findings indicated that with an appropriate addition of GG, the anisotropy index of the extrudates achieved up to 1.41, demonstrating notable anisotropy and a complex fibrous structure. Additionally, the incorporation of GG significantly improved gastric retention and increased protein digestibility to a maximum of 80.52 %. Furthermore, biphasic extrudates contained a greater proportion of bound water and exhibited enhanced moisture retention during drying and rehydration. Moreover, the Weibull function was recognized as a suitable model for describing the drying kinetics of high-moisture extrudates. The insights gained from this study will offer valuable guidance for regulating the properties of biphasic high-moisture extrudates, which is essential for the structural design and processing characteristics of plant-based products.