Comparative study of emulsifying properties in acidic condition of soluble polysaccharides fractions obtained from soy hull and defatted soy flour

Acid emulsions stabilized by soy whey concentrates and soluble soybean polysaccharides: Role of biopolymer interaction strategies on stability against environmental stresses

This article focuses on the evaluation of different interaction strategies between soy whey concentrates (SWC) and soluble soybean polysaccharides (SSPS) at pH 3.0 on the emulsion stability against freeze-thawing and mechanical stirring. Emulsions were prepared from aqueous dispersions of both biopolymers (3.0% w/w SSPS and SWC, 1:1 mass ratio) and sunflower oil (10% w/w) by aqueous phase complexation (APC), interfacial complexation (IC) and interfacial complexation and sonication (ICS). SWC control emulsion was a poor emulsifying ability; SSPS addition, through the APC and ICS strategies, noticeably improved the SWC emulsifying properties. ICS emulsions showed the highest stability to environmental stresses, due a combination of low initial particle size, flocculation degree and steric hindrance promoted by the presence of SSPS chains at the interface. This study provides valuable information forthe utilization of whey soy proteins in acid dispersed systems stable to environmental stresses.

Impact of environmental stresses on the stability of acidic oil-in-water emulsions prepared with tofu whey concentrates

The emulsifying properties of tofu-whey concentrates (TWCs) at pH 3.0, 4.0, and 5.0, and the stability of the resultant oil-in-water emulsions against freeze-thawing (24 h, −20 °C) and controlled or mechanical stress (orbital stirring at 275 rpm, 40 min) were addressed. TWCs were prepared from tofu-whey by heating at 50 °C (8.0 kPa) or 80 °C (24.0 kPa), dialysis (4 °C, 48 h), and freeze-drying, giving the samples TWC50 and TWC80, respectively. The particle size and interfacial properties at the oil/water interface were measured. Emulsions were prepared by mixing the TWC aqueous dispersions (1.0% protein w/w) and refined sunflower oil (25.0% w/w) by high-speed and ultrasound homogenization. The preparation of TWCs at higher temperatures (80 °C) promoted the formation of species of larger particle size, a slight decrease of interfacial activity, and the adsorption of more rigid biopolymer structures associated with an increase of film viscoelasticity in interfacial rheology measurements. The emulsifying properties of both concentrates were enhanced with decreasing pH (5.0–3.0), through a significant decrease of particle size (D_4,3) and flocculation degree (FD), but only those prepared with TWC80 exhibited higher stability to freeze-thawing and mechanical stress at pH 3.0. This could be ascribed to a combination of low initial D_4,3 and FD values, high protein load, and the presence of rigid species that impart high viscoelasticity to the oil/water interface. These results would be of great importance for the utilization of TWCs as food emulsifiers in acidic systems to impart high stability to environmental stresses.

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Tofu whey concentrates (TWCs) were prepared by heating (50 °C, 80 °C) at reduced pressure.

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The emulsifying properties of TWC50 and TWC80 were evaluated at pH 3.0, 4.0 and 5.0.

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The emulsifying properties of TWC50 and TWC80 were enhanced at pH 3.0.

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For TWC80 emulsions, the freeze-thaw stability was enhanced at pH 3.0.

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TWC80 emulsions showed a high stability to mechanical stress at pH 3.0.

Structure/function relationships of bean polysaccharides: A review

Beans are a rich source of high quality protein and oil, and have attracted increasing interest from both nutrition researchers and health-conscious consumers. This review aims to provide a foundation for the future research and development of bean polysaccharides, by summarizing the sources, structure, and functions of bioactive bean polysaccharides. Structure/function relationships are described, for biological activities, such as immunological, antioxidant and anti-diabetes. This will provide useful guidance for further optimization of polysaccharide structure and the development of bean polysaccharides as a novel functional material.

Contribution of soybean polysaccharides in digestion of oil-in-water emulsion-based delivery system in an in vitro gastric environment

This study aims to evaluate the effects of soy soluble polysaccharide and soy hull polysaccharide on stability and characteristics of emulsions stabilised by soy protein isolate in an in vitro gastric environment. Zeta potential and particle size were used to investigate the changes of physico-chemical and stability in the three emulsions during in vitro gastric digestion, following the order: soy protein isolate-stability emulsion < soy protein isolate-soy soluble polysaccharide -stability emulsion < soy protein isolate-soy hull polysaccharide-stability emulsion, confirming that coalescence in the soy protein isolate-stability emulsion occurred during in vitro gastric digestion. Optical microscopy and stability measurement (backscattering) also validate that addition of polysaccharide (soy soluble polysaccharide and soy hull polysaccharide) can reduce the effect of simulated gastric fluid (i.e., pH, ionic strength and pepsin) on emulsion stability, especially, soy protein isolate-soy hull polysaccharide-stability emulsion, compared with soy protein isolate-stability emulsion. This suggests that the flocculation behaviours of these emulsions in the stomach lead to a difference in the quantity of oil and the size and structure of the oil droplets, which play a significant role in emulsion digestion in the gastrointestinal tract. This work may indicate a potential application of soy hull polysaccharide for the construction of emulsion food delivery systems.

Effect of salt content and type on emulsifying properties of hull soy soluble polysaccharides at acidic pH

Hull soluble polysaccharide (HSPS) is a novel product consisting in a mixture of polysaccharides and proteins extracted from soy hulls by using a methodology based on the extraction of citric pectins. In this work we studied the effect of the addition of two different salts (NaCl and CaCl2) on the emulsifying properties of HSPS at acidic conditions. Low and high homogenization energies were used, obtaining coarse and fine emulsions, respectively. Mean droplet size, the stability against destabilizing processes (creaming, flocculation and coalescence) and the rheological properties of the emulsions were analyzed. Also, the rheology of the O/W interface was studied by using du Noüy ring geometry. Coarse HSPS emulsions were unstable to creaming, being more stable in the presence of salts. In contrast, fine HSPS emulsions showed long-term creaming stability similar to those performed with commercial citric pectin (CCP), although they differ in particle size distribution and flocculation degree. The presence of CaCl2 reduced the mean size of droplets in fine HSPS emulsions and improved their stability to flocculation and coalescence. Significant differences were observed in the rheological behavior of O/W emulsions and interfaces of HSPS and CCP with respect to the salt addition. Our results indicate that HSPS can be used in the formulation and stabilization of acidic O/W emulsions. Besides, HSPS generates emulsions with different characteristics than those obtained with citric pectins. The use of HSPS provides a suitable alternative in food engineering contributing to the exploitation and valorization of soy hulls, which represents an important waste material in soybean processing.