In vitro digestibility and functional attributes of the whey protein heat-induced hydrogels reinforced by various polysaccharides and CaCl 2

In this study, whey protein isolate (WPI) solution (12% w/v) was mixed with alginate or carrageenan at a concentration of 2.5 mg mL − 1 and then enriched with CaCl 2 (30 mM) to prepare mixed hydrogels with modulated functional properties and high stability to gastrointestinal degradation. The mixed gels enriched with CaCl 2 had higher hardness (approximately sixfold) and lower water holding capacity (WHC) compared to the other hydrogel samples ( P < 0.05). The highest (100%) and lowest (about 70%) WHC were observed for gel made of WPI/carrageenan and gel made of WPI/CaCl 2 , respectively. The WPI-alginate/carrageenan composite gels showed more homogenous and compact structure with lower pore sizes than the CaCl 2 -enriched pairs. According to the X-ray diffraction analysis, intermolecular interactions between WPI and alginate/carrageenan and CaCl 2 were occurred in the amorphous phase. Furthermore, the results revealed that the binary hydrogels made of WPI and carrageenan/alginate had lower swelling degree and protein degradation rate under simulated gastric and small intestinal conditions. Generally, the results of this study suggested that the mixed WPI-polysaccharide (alginate/carrageenan) based hydrogels can be used for the site-specific delivery of bioactive molecules and designing of novel functional foods with modulable technological functionalities.