Rheological Properties of Soybean β-Conglycinin in Aqueous Dispersions: Effects of Concentration, Ionic Strength and Thermal Treatment

Abstract

Steady shear and dynamic oscillatory measurements were used to investigate the effect of concentration, ionic strength and thermal treatment on rheological properties of soybean β-conglycinin in aqueous dispersions. SDS-PAGE and Differential Scanning Calorimetry (DSC) showed that β-conglycinin exhibited partial denaturation and formation of aggregates during isolation. Under steady shear flow, strong shear-thinning behavior was observed with increasing shear rate from 0.001 to 1200 s −1. A dispersion of β-conglycinin (≥5% w/v, without applying thermal treatment) exhibited gel-like dynamic mechanical spectra at 20 • C. This suggested that β-conglycinin in aqueous dispersions showed rheological properties of typical weak gel-like (entanglement) or semi diluted polymeric solution. Weak gel network of β-conglycinin was susceptible to ionic strength, suggesting that electrostatic forces play an important role in the formation of weak gel network. These properties of β-conglycinin have practical significance for the food processors in the formulation of new products.

Rheological and Solubility Properties of Soy Protein Isolate

“…Thereafter, the G ″ > G ′ for all dispersions, signifying the transition from a weak gel to a more viscous liquid-like system [ 39 ]. Previously, Liu et al (2011) showed that the critical concentration of an SPI dispersion to form a weak gel-like structure was approximately 5% ( w/w , protein), with protein concentrations less than 5% ( w/w ) showing only viscous behaviour (i.e., G ″ > G ′) [ 26 ]. Ultimately, the data in Figure 7 confirm that the SPI dispersions have elastic-like behaviour at low frequencies but convert to viscous type systems at frequencies of ≈10 Hz or higher.…”

“…This can result in inaccurate soy protein solubility values, which is the reason why a particular focus on soy protein solubility was undertaken in this study. In fact, Liu et al (2011) showed that SPI dispersions at concentrations of 5%, w/w, protein displayed a weak-gel-like property during low oscillatory measurements [26]. These physicochemical properties make soy protein an ideal ingredient for some product applications such as plant-based yogurts, high protein powders, or soy-based beverages in the form of an oil-in-water emulsion; however, to the authors' knowledge a commercially available soluble soy protein based beverage without oil addition does not exist.…”

Stabilization of oil-in-water emulsions via soy protein and soy soluble polysaccharide interactions

“…In order for proteins to effectively stabilize emulsion droplets against coalescence, they must be present in sufficiently high concentration to fully cover the droplets [5]. Generally, increasing the concentration of SPI leads to more stable emulsions [47,48]. Under controlled conditions, one can induce partial denaturation of the proteins which may lead to improved emulsifying and stabilizing capabilities [19,38], as when they are partially denatured, they have improved freeze-thaw stability and increased tolerance to salt [19,45].…”

Gelation Property of Alcohol-Extracted Soy Protein Isolate and Effects of Various Reagents on the Firmness of Heat-Induced Gels

“…[32] In the overall balance of attractive and repulsive forces contributing to soy protein gel network formation, hydrogen bonds, and hydrophobic and electrostatic interactions are all believed to be important. In a most recent study, Liu et al [33] found that weak gel network of soy β-conglycinin was susceptible to ionic strength, suggesting that electrostatic forces play an important role in the formation of weak gel network.…”