The effects of resonance acoustic mixing on Ca2+- induced gelation of commercial soy protein isolate

This study reported a new physical processing technology, resonant acoustic mixing (RAM), for the modification of commercial soy protein isolate (SPI) to enhance its gelling properties, and the underlying mechanisms were investigated. With the increase of treatment time, the β-sheet of SPI increased (from 28 % to 31 %) and α-helices content decreased (from 28 % to 26 %), which suggested that RAM treatment could promote the unfold of SPI and further induced the exposure of reactive groups. The exposure of sulfhydryl and hydrophobic groups in SPI molecules after RAM treatment led to the formation of a large number of disulfide bonds and enhanced hydrophobic interaction during the formation of Ca 2+ -induced gel, which further enhanced the gel hardness and WHC as well as other texture properties including chewiness and gumminess. In addition, RAM treatment significantly reduced the protein particle size and increased the solubility of SPI, resulting in the formation of compact and dense microstructures of gel with enhanced viscoelasticity. However, the influence on nonlinear rheological properties could be ignored. Particularly, SPI with desired structural and gelling properties was obtained under RAM treatment for 25 min. These results could provide theoretical guidance for the utilization of RAM as a modification technique for food protein. • RAM treatment promoted the unfold of SPI and exposure of reactive groups. • RAM treatment significantly increased the solubility of commercial SPI. • RAM treatment enhanced the hardness, WHC, and viscoelasticity of SPI gels. • The optimal RAM treatment time for commercial SPI was 25 min.