Enhancement by gellan gum on acid-induced gels of rice-soy protein using high-energy fluidic microfluidizer coupled with alkali-driven pretreatment

• The HEFM-alkali-driven treatment enhanced the acid-induced gelation properties of the protein. • The minimum gelation concentration of the rice-soy composite protein was 4%. • GG improved the viscoelasticity, water holding capacity, and gel strength of RSP gel. • The RSP-GG composite gel exhibited a dense and compact microstructure. This study found that the acid-induced gelation performance of rice-soy composite protein prepared by high-energy fluidic microfluidizer coupled with alkali-driven treatment was superior to that treated solely by alkali-driven or conventional preheated treatment. The minimum gelation concentration can be reduced to 4% (RSP), significantly lower than that of heat-pretreated SPI (10%). The mechanical properties and rheological tunability were further improved by incorporating gellan gum (GG). A 0.4% concentration of GG increased the hardness and chewiness of RSP gel by 61 and 42 times, respectively. SAOS and LAOS results demonstrated that GG incorporation significantly enhanced the modulus, reduced the phase angle, and improved strain resistance. Intermolecular interaction and FTIR analyses revealed that GG incorporation attenuated electrostatic interactions, enhanced hydrogen bonds and hydrophobic interactions, and increased β-sheets content. Additionally, microscopy observations indicated that GG facilitated the stacking of proteins into a denser and more compact structure. Specifically, low concentrations of GG induced the formation of large aggregates that interconnected into a network, whereas high concentrations of GG suppressed the generation of large aggregates. This enhanced stacking compactness contributed to reduced water mobility and improved WHC. In conclusion, HEFM-alkali-driven pretreatment combined with GG incorporation provided valuable insights for developing innovative low-protein gel foods with high nutritional value.