Evaluation on pH-dependent thermal gelation performance of chickpea, pea protein, and casein micelles

Concerns about health, the environment, and sustainable food supply have inspired researchers into searching new alternative plant proteins to dairy proteins. This study investigated thermal treatment coupled with pH manipulation (3.0, 5.0, 7.0, and 9.0) on the structural and gelation performance of pea, chickpea protein, and casein. Gel electrophoresis suggested that only specific fractions contributed to disulfide bond-mediated aggregates formation: bovine κ-casein and αs2-casein in casein micelles, acidic and basic legumin subunits in pea and chickpea protein. No protein formed self-standing gels but precipitated in macroscopic flocs at pH 5.0. Casein displayed optimum gel performance at pH 3.0 (storage modulus (G′) of 2596.00 Pa, hardness of 603.47 g, water holding capacity of 94.92%), and transitioned into fluid-like viscous state (G′ < 1, loss tangent >1) under neutral or higher pH conditions. Pea protein did not form self-holding gels but aggregates with globular particles over all test pH. Nevertheless, chickpea protein formed self-standing gels regardless of pH (except 5.0) and peaked gel performance at pH 9.0. Hence, this study indicated considerable potential of casein in acidic thermal gel-based food products and confirmed the promising applications of chickpea protein as an alternative to pea protein across diverse pH conditions, and to casein in neutral and alkaline food gel formulations. In addition to providing scientific insight understanding the effects of thermal treatment coupled with pH manipulation on the performance of plant-based protein and dairy protein, this research sheds light on the promising prospects of incorporating chickpea protein into gel-based food formulations.