Fabrication of amorphous pea starch-whey protein emulsion gels for synergistic stabilization, nutrient delivery, and...

The amorphous pea starch (PeS)-whey protein isolate (WPI) mixture was demonstrated as an effective emulsifier in our previous study. Herein, we systematically investigated the effects of PeS/WPI ratio (0:6-6:0), total solid concentration (4-8 %), oil phase volume fraction (30-70 %), and environmental conditions (pH 3-11, 0-300 mmol/L NaCl) on the characteristics of the emulsion gels as well as their applications as nutrient carriers and solid fat replacers. An optimized formulation (4:2 PeS/WPI ratio, 8 % concentration, 60 % oil) yielded emulsion gels with superior stability (no creaming), gel strength (69.40 g), water-holding capacity (98.53 %), and elastic-dominated network structure (G' > G″), which were attributed to synergistic effects between the starch gel network and protein-mediated inter-droplet interactions. Environmental tests showed pH- and ionic strength-dependent structural responses, with optimal performance at pH 7 and 0 mmol/L NaCl. The bioavailability of β-carotene followed a trend similar to free fatty acid release, with both depending on the structural state of the emulsion gel. Notably, emulsion gels with PeS/WPI ratios of 2:4 and 1:5 exhibited superior β-carotene bioavailability. Pound cakes in which 33.3 % of the butter was replaced with the emulsion gel retained a quality comparable to butter cakes, whereas replacing 66.7 % and 100 % of the butter increased their moisture retention, specific volume, hardness, springiness, and resilience. This work provides mechanistic insights into starch-protein hybrid emulsion gels and demonstrates their potential for tailored food applications.