Whey protein gel particles as clean-label pickering stabilizers in frozen yogurt

Emulsifiers and stabilizers are essential ingredients in frozen desserts, creating microstructures that enhance texture and storage stability by stabilizing air bubbles and increasing unfrozen matrix viscosity. The clean label movement has prompted the food industry to seek natural alternatives to synthetic emulsifiers and certain stabilizers. Pickering stabilization using biopolymer microgels has emerged as a promising approach, offering superior long-term stability for food emulsions and foams. Frozen yogurt was used as the model system in this study because its lower fat content and lower pH, relative to ice cream, place greater demands on stabilization of the air and fat phases, offering a rigorous test of the functionality of the gel particles. This study investigated the effects of whey protein gel particles on frozen yogurt properties, examining both the mix and final product characteristics. Whey protein gel particles were prepared by heating whey protein concentrate (WPC) at pH 7.0 and 85°C for 30 min, followed by sonication and pH adjustment to 4.0, 4.5, or 5.0. Partial replacement of nonfat dry milk (NDM) with WPC gel particles in frozen yogurt mixes resulted in smaller fat globule sizes, increased overrun, and enhanced foam stability. The most notable improvement was in melting properties, as evidenced by a prolonged induction time and reduced drip-through rate. Descriptive sensory analysis indicated that WPC gel particle-containing frozen yogurts exhibited slower meltdown, though with elevated intensities of cardboard flavor and astringency relative to the control, attributable to the thermal processing of the gel particles. These off-flavor attributes represent a key area for formulation refinement. The enhanced foaming properties were attributed to the combined mechanisms of increased continuous phase viscosity and Pickering stabilization by the gel particles.