Improvement of soybean protein isolate/konjac glucomannan-seaweed polysaccharide-based connective tissue simulants: effects of pH and water mobility on gel structure and gelling mechanism

Hydrogels are considered to have good potential to mimic connective tissue. In this study, the mechanical properties and thermal stability of protein-polysaccharide composite hydrogels were enhanced by moisture and acid-base modulation in an attempt to overcome the application limitations. The results of texture profile analysis (TPA) and compression experiments showed that the appropriate outward migration of moisture significantly improved the gel's mechanical properties. Rheological analysis showed that the gel exhibited optimal mechanical properties under an alkaline environment and, combined with the differential scanning calorimetry (DSC) results, excellent thermal stability was observed in the pH 10.5 sample group. Furthermore, magnetic resonance imaging (MRI) and scanning electron microscopy (SEM) results showed that the alkaline environment was also conducive to the formation of a denser gel network structure, and the outward migration of water led to a more orderly and uniform structure. Fourier transform infrared spectroscopy (FTIR) results showed that hydrogen bonding also played a major role in the formation of the cellular network structure of the gel. These findings demonstrate the positive contribution of moisture and pH modulation to the processing and edible property enhancement of animal connective tissue-mimicking structure and provide a theoretical basis for the regulation of hydrogel properties.