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

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.

Eco-Friendly Electrospun Nanofibers Based on Plant Proteins as Tunable and Sustainable Biomaterials

“…On the other hand, samples of PEA-72% and SOY-72% nanofibers are characterized by a broader amide I peak compared to POTATO-72%, centered in the region around 1660 cm –1 , indicating larger structural heterogeneity. These spectra resemble the spectra that we have previously reported for soy protein isolate, where the contribution of aggregated β-sheet structures was identified together with content of native β-sheet typical of soy protein and native α-helical structures, turns, and loops; similar structures have been also previously discussed for pea − and soy protein isolates , in solution or powder form.…”

Improving the Storage Stability of Soy Protein Isolate through Annealing

“…Figure 2 illustrates the particle size distributions of NSPI and HSPI annealed at 65 °C over a 12-week storage period. Their distributions manifested a distinct bimodal pattern, wherein HSPI, having undergone thermal denaturation, exhibited protein particle aggregation, resulting in a rightward shift (indicating larger particle sizes) of the two peaks [24]. At week 0, the protein particle size increased with increasing annealing time (Figure 2A), probably attributed to the aggregation induced by the heat The effects of different annealing conditions on solubility change during HSPI storage were diverse.…”

Concentration-Regulated Fibrillation of Soy Protein: Structure and In Vitro Digestion

“…Soy protein isolate (SPI), a commercially available protein with excellent processability (e.g., gelation, emulsification, and water/fat binding) and biocompatibility, has been applied as an important functional ingredient in a range of foods, such as high-protein tofu, plant protein beverage, sausage, and other food formulations. − Moreover, SPIs also possess a well-balanced amino acid composition with better economic viability and environmental sustainability than animal proteins . To date, a number of treatments, such as heat, pH-shifting, and proteolysis, have been widely adopted to modify original SPI structures with the intention of improving functionalities for particular food applications. Given the existing criteria for high quality and effective productivity of modified protein matrices, there is an ongoing need to expand their application in food products by introducing a new portfolio of alternative processing routes …”

“…1−3 Moreover, SPIs also possess a wellbalanced amino acid composition with better economic viability and environmental sustainability than animal proteins. 2 To date, a number of treatments, such as heat, 4 pH-shifting, 5 and proteolysis, 6 have been widely adopted to modify original SPI structures with the intention of improving functionalities for particular food applications. Given the existing criteria for high quality and effective productivity of modified protein matrices, there is an ongoing need to expand their application in food products by introducing a new portfolio of alternative processing routes.…”