The role of protein concentration in heat‐induced particulation of soy proteins at different pHs: Structure and functional properties

Abstract

Abstract Protein particulation is a modification strategy for the optimization of the use of protein materials. The development and subtypes of particulate structures are largely dependent on the aggregated state of proteins after heat‐induced interactions, which is profoundly influenced by protein concentration (PC). In this work, the impact of PC below and above the critical gelation point, that is, 5% (w/v) and 10% (w/v), on the structure and functional properties of heat‐treated soy protein isolates (SPIs) at different pHs (2.0, 4.0, and 7.0), was investigated. The results showed that heat‐induced aggregation of SPIs was promoted by increasing the PC, leading to a β‐sheet‐dominated secondary structure. At pH 2.0 and 7.0, the 10% SPIs exhibited larger particle size and lower solubility, surface hydrophobicity index, and oil‐holding capacity compared to the 5% SPIs after heating. Furthermore, at neutral pH, the 10% SPI microgels had higher storage modulus (G′) and loss modulus (G″) than their acidifying counterparts, as well as the excellent emulsifying property for oil droplet stabilization. These findings would provide the theoretical basis for the structure modification and function improvement of plant proteins and, therefore, broaden the application of plant proteins in the food industry.

Keywords

• functional properties
• heat treatment
• protein concentration
• soy protein isolate
• structure