Gel Characteristics and Digestion of Composite Protein Emulsion-Filled Gels with Varying Soy and Whey Protein Ratios in the Matrix

The effect of mixed soy and whey protein in the matrix on properties and digestion characteristics of emulsion-filled gels was investigated. Different matrix protein concentrations (8-14%) with a composite soy and whey protein (SW) ratio of 5:5 were screened using gel hardness. The better-performing gel (13%) was selected for matrix composition studies. Soy and whey composite protein mixed at different ratios (S/W = 0/10, 3/7, 5/5, 7/3, and 10/0) was dispersed into another soy-whey (S/W = 6/4) composite emulsion and gelled thermally. Different hybrid protein ratios in the matrix can alter the textural and rheological properties and, consequently, the digestion kinetics of mixed plant-animal gel systems. The storage modulus was highest at an S/W ratio of 0/10. The hardness of gel with the S/W ratio matrix of 0/10 was 3.10 and 9.60 times higher than that of 5/5 and 10/0 (<i>p</i> < 0.05). The SW ratio did not affect water-holding capacity or springiness (<i>p</i> > 0.05). All the gels had swelling ability below 10% except SW 10/0 (around 60%). Gels with an S/W of 5/5 exhibited a lower hydrolysis degree and rate during gastric digestion, while the reverse occurred during intestinal digestion. The compact gel network might limit pepsin's accessibility to cleavage sites.