Enhancing the gel properties of soy protein isolate: the role of oxidized konjac glucomannan in acid‐induced gelation

Abstract Background Soy protein isolate (SPI) gels formed using a single coagulant often have poor water‐holding capacity (WHC) and low hardness, making them fragile and unsuitable for transportation and storage. Adding compound coagulants or polysaccharides can improve the gelation properties of SPI gels induced by gluconolactone (GDL). This study explores the impact of oxidized konjac glucomannan (OKGM) on the physicochemical and structural properties of GDL‐induced SPI gels, with the aim of evaluating the potential of OKGM for enhancing the overall quality and stability of these gels. Results In this study, the composite gels demonstrated a significant increase in whiteness (69.02% to 70.59%) compared with the SPI gel (67.41%). Key physicochemical properties, such as water‐holding capacity (WHC), textural characteristics, viscoelasticity, and thermal stability, were notably improved. Scanning electron microscopy (SEM) revealed a reduction in the average pore diameter of the composite gels from 70.57 ± 4.13 μm to 37.19 ± 0.24 μm when the oxidation degree of OKGM was kept at or below 60 min, contributing to a more compact and orderly microstructure. Enhanced hydrophobic and electrostatic interactions within the composite gels also accelerated the gelation process, shortening the gelation time from 15.77 ± 0.37 min to 12.45 ± 0.18 min. Conclusion The results demonstrate that OKGM acts effectively as a gel enhancer, improving the physicochemical and structural properties of SPI gels significantly. © 2024 Society of Chemical Industry.