Effect of ultrasound-assisted pH-shifting treatment on the physicochemical properties of mung bean protein/milk protein concentrate hybrid protein systems and its application in hybrid yogurt gels.

This study aimed to explore the impact of ultrasound-assisted pH-shifting on the physicochemical characteristics of a mung bean protein/milk protein concentrate (MBP/MPC) hybrid protein system and assess its applicability in hybrid yogurt gels. The results indicated that ultrasound and pH-shifting synergistically improved the physicochemical properties of hybrid protein system, increasing solubility (86.92 %-91.98 %), enhancing emulsification (4.08 %-53.65 %), and reducing particle size (8.02 %-87.87 %). Additionally, ultrasound-assisted pH-shifting significantly decreased α-helix and β-turn contents while increasing random coils content, without altering the protein's primary structure. In hybrid yogurt gel applications, ultrasound-assisted pH-shifting markedly improved gel texture, water-holding capacity, and elasticity. However, when the MBP/MPC ratio exceeded 60:40, the hybrid gels exhibited inferior properties compared to mung bean protein single yogurt gels, even after treatment. The best gel quality was attained at an 80:20 MBP/MPC ratio, where hydrophobic interactions were identified as the dominant factor in gel network formation. These findings suggested that the quality of hybrid protein yogurt gels strongly depends on the MBP/MPC mixing ratio. This study provides a theoretical basis for applying ultrasound-assisted pH-shifting in MBP/MPC hybrid protein yogurt gel systems.