Foaming, emulsifying properties and surface hydrophobicity of soy proteins isolate as affected by peracetic acid oxidation

Junsheng Li,Bixuan Wang,Junfu Fan,Xin Zhong,Guoxia Huang,Liujuan Yan,Xiane Ren

doi:10.1080/10942912.2019.1602540

Junsheng Li, Bixuan Wang + Show 5 more

Open Access

https://doi.org/10.1080/10942912.2019.1602540

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Abstract

ABSTRACTIn this study, the effects of the disulfide bond cleavage induced by peracetic acid oxidation on the surface properties and surface hydrophobicity of soy proteins isolate (SPI) were investigated. The surface hydrophobicity, foaming capacity and emulsifying capacity of oxidized-SPI increased gradually at the initial stage with the increase of peracetic acid concentration. When the concentration of peracetic acid was increased up to 0.4%, compared with that of native SPI, the surface hydrophobicity, foaming capacity, emulsifying capacity and emulsifying stability of oxidized-SPI increased by 114.0, 81.4, 65.2, 49.8%, respectively, and achieved optimal results. However, excessive oxidation led to a decrease in surface hydrophobicity, foaming capacity and emulsifying stability of SPI, but it had no obvious effect on the foaming stability and emulsifying capacity of SPI. The foaming capacity, emulsifying capacity and emulsifying stability of SPI were positively related to the changes of surface hydrophobicity which caused by disulfide bond cleavage. The results of fluorescence spectroscopy, CD spectroscopy, and particle size analysis showed that the disulfide bond cleavage did cause great changes in the molecular structure of SPI, but there was no clear correlation between the molecular structural change and the surface activity of SPI. These suggested that the improvement of foaming capacity, emulsifying capacity and emulsifying stability of SPI could be achieved by changing its surface hydrophobicity via peracetic acid oxidation.

Highlights

Similar to traditional surfactant molecules, a protein molecule has both hydrophobic and hydrophilic parts
Excessive oxidation led to a decrease in surface hydrophobicity, foaming capacity and emulsifying stability of soy proteins isolate (SPI), but it had no obvious effect on the foaming stability and emulsifying capacity of SPI
The results of fluorescence spectroscopy, Circular dichroism (CD) spectroscopy, and particle size analysis showed that the disulfide bond cleavage did cause great changes in the molecular structure of SPI, but there was no clear correlation between the molecular structural change and the surface activity of SPI

Summary

Introduction

Similar to traditional surfactant molecules, a protein molecule has both hydrophobic and hydrophilic parts. Enhancing the surface activity of proteins by changing the molecular structure of proteins, such as ultrasound treatment[1], heating and chemical modification[2,3], is a necessary technical way to expand and utilize their surface activity It is the amphiphilic nature of the protein that makes the polypeptide chains automatically fold into spherical molecules in the aqueous environment because the non-polar solutes have a tendency to adhere to one another in an aqueous environment (socalled hydrophobicity).[4] The automatic folding of protein polypeptide chains leads to a situation that most of the non-polar amino acid residues are embedded within the protein molecules to form

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