Fabrication, in-vitro digestion and pH-responsive release behavior of soy protein isolate glycation conjugates-based hydrogels

Hydrogel made by glycated soy protein isolate (SPI) conjugates is a promising gastrointestinal targeted delivery system for bioactives. In this study, SPI conjugates were prepared with dextran molecules at various molecular weights by Maillard reaction -based heating, and then used to fabricate hydrogel aided by transglutaminase. The modification on the structure, interfacial and rheological properties of SPI by dextran was studied. The physicochemical properties, digestion behavior and curcumin-encapsulation capacity of resultant SPI-dextran hydrogels were comprehensively studied. As compared to SPI and SPI-glucose conjugates-based hydrogels, SPI-dextran hydrogels showed lower mechanical properties but more homogeneous gel network. Dextran with higher molecular weight showed lower grafting degree on SPI, but was more effective on improving the thermos-set gel performance, and resistance to in vitro gastrointestinal digestion. The contribution of glycinin and β-conglycinin, two major individual proteins of SPI, in the dextran conjugates formation were predicated by molecular docking for the first time. The impact of molecular weight of dextran on glycated SPI hydrogel-based delivery systems was comprehensively investigated, which is promising for development of functional food applications.