Surface Properties of Heat‐Induced Soluble Soy Protein Aggregates of Different Molecular Masses

Abstract

Suspensions (2% and 5%, w/v) of soy protein isolate (SPI) were heated at 80, 90, or 100 °C for different time periods to produce soluble aggregates of different molecular sizes to investigate the relationship between particle size and surface properties (emulsions and foams). Soluble aggregates generated in these model systems were characterized by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Heat treatment increased surface hydrophobicity, induced SPI aggregation via hydrophobic interaction and disulfide bonds, and formed soluble aggregates of different sizes. Heating of 5% SPI always promoted large-size aggregate (LA; >1000 kDa) formation irrespective of temperature, whereas the aggregate size distribution in 2% SPI was temperature dependent: the LA fraction progressively rose with temperature (80→90→100 °C), corresponding to the attenuation of medium-size aggregates (MA; 670 to 1000 kDa) initially abundant at 80 °C. Heated SPI with abundant LA (>50%) promoted foam stability. LA also exhibited excellent emulsifying activity and stabilized emulsions by promoting the formation of small oil droplets covered with a thick interfacial protein layer. However, despite a similar influence on emulsion stability, MA enhanced foaming capacity but were less capable of stabilizing emulsions than LA. The functionality variation between heated SPI samples is clearly related to the distribution of aggregates that differ in molecular size and surface activity. The findings may encourage further research to develop functional SPI aggregates for various commercial applications.

Subcritical Water Induced Complexation of Soy Protein and Rutin: Improved Interfacial Properties and Emulsion Stability

“…In the absence of rutin, SW‐induced protein (HSPI) has a significantly ( P < 0.05) larger hydrodynamic radius ( R h ) than native protein (NSPI), but R h did not differ significantly before and after the introduction of rutin for native and heated protein, which agrees well with the previous observations on the enrichment of catechin to pectin (Oliveira and others ). This phenomenon was attributed to the unfolded proteinsand soluble aggregates formation during SW treatment (Wang and others ; Guo and others ). The hydrodynamic radius of NSPI–rutin mixture was smaller than that for NSPI, as well as for the HSPI–rutin mixture compared to HSPI.…”

Role of interfacial protein membrane in oxidative stability of vegetable oil substitution emulsions applicable to nutritionally modified sausage

“…With an appropriate temperature-time combination, for example, 80°C for 30 min or 90°C for a few seconds, soy and whey proteins can undergo certain conformational change to expose hydrophobic groups (Feng, Xiong, & Mikel, 2003). Aggregates formed by subsequent hydrophobic and disulfide aggregation also contribute to the emulsifying activity and emulsion stability (Guo et al, 2015;. Knudsen, Øgendal, and Skibsted (2008) found that thermal aggregates of β-lactoglobulin, the most abundant protein in whey, improved the apparent viscosity of emulsions.…”

Effect of Soybean Soluble Polysaccharide on the Formation of Glucono-δ-Lactone-Induced Soybean Protein Isolate Gel

“…Generally, after thermal denaturation, unfolding, and molecular aggregation, soybean proteins were cross-linked to form a three-dimensional network gel [2]. It has been reported that many factors can affect the formation of protein gels, such as pH, coagulant, heating method, protein concentration, and addition of sugars [3][4][5]. Therefore, it is valuable to study the effects of other ingredients and treatment conditions on the production of protein-based products.…”