Improvement on soy protein isolate function via combined treatment of ultrasound and basic amino acids
In order to investigate the influence of ultrasound and basic amino acid(BAA)combined treatment(hereafter called combined treatment)on the structural and functional properties of soy protein isolate(SPI),the surface hydrophobicity,fluorescence spectra,Zeta potential,average particle size,free sulfhydryl group,total sulfhydryl group,relative solubility,secondary structure,sodium dodecyl sulfate-polyacrylamide gel electrophoresis,emulsification and emulsification stability of SPI treated with ultrasound,BAA or both were compared,and the correlation analysis based on some results was performed.The results showed that,compared to BAA treatment alone,the combined treatment enhanced the emulsification and relative solubility of SPI,and improved surface charges and electrostatic repulsion between the protein particles.And more hydrophobic groups were exposed to the polar environment,promoting the ratio of hydrophilic/hydrophobic groups of SPI,which was conducive to the SPI emulsification ability.The free sulfhydryl group exposure was increased,with the total sulfhydryl group content decreased,which was beneficial for SPI transformation into ordered molecular structure.The structure of SPI subunit was not changed by ultrasound or BAA alone or combined treatment.The correlation between surface hydrophobicity and relative solubility as well as emulsification was 0.960 and 0.861,respectively,showing a very significant positive correlation.The correlation between Zeta potential and relative solubility was-0.974,demonstrating a very significant negative correlation.
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