Rheological and Tribological characteristics of soy-whey dual-protein gels with whey protein microparticle...

This study investigated the influence of different types of whey protein microparticles (acid or ion induced with different particles size) on the physical properties of soy protein gels. The gelling behavior, rheological properties, and tribological properties of gels were characterized. The total protein content of the gels was maintained at 4.5 % and part of the soy proteins (0.5 %-1.5 %) were replaced with whey protein particles. When SPI was partly replaced by acid-induced particles of all studied sizes, the apparent viscosity of dual-protein gels increased, and the enhancement effect was more pronounced with a higher substitution ratio. Acid induced small-size particle (SP-acid) and medium-size particle (MP-acid) significantly enhanced the gel strength of the protein gel at 1.0 % substitution ratio, as evidenced by the dynamic oscillatory results. The ion-induced particles of all studied sizes (SP-ion, MP-ion and LP-ion) caused acceleration of gel formation and resulted in poor network formation, manifested by lower G' values at the end of the cooling process and poor water holding capacity. The apparent viscosity of the SP-ion gel was significantly lower than SP-acid at 1.0 % and 1.5 % substitution ratios. The friction results showed that the SP-acid and SP-ion increased the friction of the dual-protein gels, while LP of both acid or ion-induced particles improved the lubricating properties of gels compared to SPI. Hence, the properties of dual-protein gels can be modulated by using different types of whey protein microparticles. LP-acid could be a promising strategy for improving the texture of soy-whey dual-protein gels.