Multi-frequency ultrasound improves the functional characteristics of soybean protein isolate by promoting
Minghui Li1, Yuze Zhou1, Yuqing Duan2
1School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
Abstract:
The effects of multi-frequency ultrasound-assisted germination on the functional characteristics of soybean protein isolate (SPI), and the changes in SPI physiochemical properties were investigated in this study, as well as their intrinsic relationship with molecular structure of SPI. Compared with single-frequency ultrasound (SFU), multiple-frequency ultrasound with dual frequency (DFU) and triple-frequency (TFU) dramatically improved the functional characteristics of SPI. Among them, DFU-assisted germination (DFUG) was the most efficient strategy, which not only increased the solubility (29.15 %), water-holding ability (20.74 %), foaming and emulsifying capacity of SPI (35.24 %, and 167.16 %, respectively), but also improved its tertiary structure, with maximum particle size (1225 nm), higher zeta-potential (-52 mv), suitable surface hydrophobicity (5638), and the highest structural orderliness (lowest random coil content, 12.36 %), free sulfhydryl content (10 μmol/L). Correlation analysis revealed that these changes in SPI molecular structure are the critical factors in enhancing its functional properties. Moreover, DFUG improved the nutritional values of SPI via regulating the amino acid composition and gastrointestinal digestibility. Overall, this study confirmed the great potential of multi-frequency ultrasound to improve SPI functional characteristics by promoting germination.
