Impact of Insoluble Dietary Fiber and CaCl2 on Structural Properties of Soybean Protein Isolate-Wheat Gluten Composite Gel

Characterization of the effects of insoluble soybean polysaccharides on the formation and physicochemical properties of soybean isolate protein gel

The effects of insoluble soybean polysaccharides (ISPS) on the formation and physicochemical properties of soybean protein isolate (SPI) gel were studied. As ISPS concentration increased, SPI suspensions showed reduced surface hydrophobicity and zeta-potential and enhanced thermal stability. However, the zeta-potential increased after gel formation. The ISPS decreased the hardness of the 6 % SPI gel, which could be attributed to the fact that ISPS reduced the elasticity of gel network, making the microstructure loose and porous and behaving as a weak gel; however, for the 10 % SPI gel, the ISPS promoted the increase in hardness and exhibited a weaker negative impact on the textural and microstructural properties of SPI gel. Results revealed that ISPS could react with SPI via non-covalent bonds and embedded into the protein network, weakening or strengthening the structure and texture of SPI gel and this impact is related to the mass ratio between these two biopolymers.

Effects of soybean insoluble dietary fiber and CaCl2 on the structure and properties of low-moisture extruded products

BACKGROUND

Texturized vegetable protein is currently a leading alternative to animal meat. This study examined the effects of soybean insoluble dietary fiber (SIDF) (0% to 20%) and CaCl2 (0% to 1%) on the structure and properties of extruded products made from a soybean protein isolate-wheat gluten (SPI-WG) composite.

RESULTS

The study showed that SIDF (4% to 8%) increased the viscosity of extruded products, enhanced their specific mechanical energy, and improved their rehydration rate and tensile strength compared with a control group. The rehydration rate of the extruded products reached a maximum value of 331.67% in the 8% SIDF, 0.5% CaCl2 groups. The addition of excess SIDF prevented the cross-linking of protein molecules to form a loose network structure. Analysis of the infrared spectrum and intermolecular forces showed that physical interactions between fibers and proteins were the dominant forces, with hydrophobic interactions and hydrogen bonds primarily maintaining the structure of the extruded products. The addition of CaCl2 (0.5%) led to protein aggregation and further improved the rehydration and tensile strength of extruded products.

CONCLUSION

Soybean insoluble dietary fiber can improve the rehydration rate and quality of extruded products. The addition of CaCl2 mitigated the weakening of the protein structure caused by excess SIDF. These results provide a basis for the improvement of the quality of low-moisture-extruded texturized vegetable protein products with a high dietary fiber concentration and a high rehydration rate. © 2024 Society of Chemical Industry.

Ultrasonic treatment of emulsion gels with different soy protein-hemp protein composite ratios: Changes in structural and physicochemical properties

To improve the emulsion gel system of single soybean isolate protein (SPI) and to broaden the application field of hemp protein isolate (HPI), ultrasonic treatment and HPI were introduced to improve the properties of SPI emulsion gel and to explore the mechanism. The results showed that the gel strength (218.6 g) and water-holding capacity (86.24 %) of the emulsion gels were improved under ultrasonic treatments when the ratio of SPI:HPI was >6:4, and the reticulation structure of the gels was enhanced. When the ratio of SPI:HPI was <6:4, the gel structure was loose and formless. Ultrasonic treatment has a significant effect on the emulsion gel with the ratio of SPI:HPI was >6:4. Appropriate ultrasonic treatment (400 W) changed the protein structure, improved the rheological properties of emulsion gels to form the protein-oil-coated network structure. However, excessive ultrasonic treatment (600 W) will destroy the conformation of the protein, reducing the stability of the structure. The effect of ultrasonic treatment on emulsion gels with the ratio of SPI:HPI was <6:4 is low, but improved the gel protein digestibility. This study provides a theoretical basis for the application of ultrasonic in composite protein emulsion gels systems and the development and application of HPI.

Conformational changes induced by cellulose nanocrystals in collaboration with calcium ion improve solubility of pea protein isolate

The low solubility of pea protein isolate (PPI) greatly limits its functional properties and its wide application in food field. Thus, this study investigated the effects and mechanisms of cellulose nanocrystals (CNC) (0.1-0.4 %) and CaCl2 (0.4-1.6 mM) on the solubility of PPI. The results showed that the synergistic effect of CNC (0.3 %) and Ca2+ (1.2 mM) increased the solubility of PPI by 242.31 %. CNC and Ca2+ changed the molecular conformation of PPI, enhanced intermolecular forces, and thus induced changes in the molecular morphology of PPI. Meanwhile, the turbidity of PPI decreased, while surface hydrophobicity, the absolute zeta potential value, viscoelasticity, β-sheet ratio, and thermal properties increased. CNC bound to PPI molecules through van der Waals force and hydrogen bond. Ca2+ could strengthen the crosslinking between CNC and PPI. In summary, it is proposed a valuable combination method to improve the solubility of PPI, and it is believed that this research is of great significance for expanding the application fields of PPI and modifying plant proteins.

Tapioca Starch Improves the Quality of Virgatus nemipterus Surimi Gel by Enhancing Molecular Interaction in the Gel System

The gel prepared using Nemipterus virgatus (N. virgatus) surimi alone still has some defects in texture and taste. Complexing with polysaccharides is an efficient strategy to enhance its gel properties. The main objective of this study was to analyze the relationship between the gel quality and molecular interaction of N. virgatus surimi gel after complexing with tapioca starch. The results make clear that the gel strength, hardness, and chewiness of surimi gel were increased by molecular interaction with tapioca starch. At the appropriate addition amount (12%, w/w), the surimi gel had an excellent gel strength (17.48 N), water-holding capacity (WHC) (89.01%), lower cooking loss rate (CLR) (0.95%), and shortened T2 relaxation time. Microstructure analysis indicated that the addition of tapioca starch facilitated even distribution in the gel network structure, resulting in a significant reduction in cavity diameter, with the minimum diameter reduced to 20.33 μm. In addition, tapioca starch enhanced the hydrogen bonding and hydrophobic interaction in the gel system and promoted the transformation of α-helix to β-sheet (p < 0.05). Correlation analysis showed that the increased physicochemical properties of surimi gel were closely related to the enhanced noncovalent interactions. In conclusion, noncovalent complexation with tapioca starch is an efficient strategy to enhance the quality of surimi gel.