Emulsifying and Foaming Properties of Soy Protein Isolates with Covalent Modification by (-)-Epigallocatechin-3-Gallate

M Zheng,Z.B Jia,J.X Jiang

doi:10.19026/ajfst.6.17

Abstract

Soy Protein Isolates (SPI) with covalent modification by (-)-Epigallocatechin-3-Gallate (EGCG) were prepared under the alkaline condition. The effects of covalent modification on the emulsifying and foaming properties of SPI were evaluated. The Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) profiles of the modified SPI revealed that EGCG treatment caused cross-linking of subunits. Emulsifying activity of modified SPI significantly increased when compared with that of control (p<0.05) at the concentration of 35 mg/mL. Modification of SPI by EGCG caused a decrease in the foam volume initially. In the range of 15 to 35 mg/mL, the foaming activities of modified SPI were found to be less than those of the control (p<0.05). The foaming stabilities of modified SPI were significantly higher when compared to those of control (p<0.05). The results obtained in this study indicated the modification by EGCG resulted in the enhancement of emulsifying activity and foaming stability of SPI. This modification may serve as a promising approach for improving functional properties of SPI.

Highlights

Soy Protein Isolates (SPI) is the most highly refined soy products commercially available and represent the major protein fraction of the soy bean
Chemical modification has been developed to improve the functional properties of SPI and to promote its utilizations in food products (Babiker et al, 1998; Matemu et al, 2011)
The SDS-PAGE profiles of modified SPI (Fig. 1, lane 2) revealed that EGCG treatment caused cross-linking of subunits, as evidenced by the disappearance on the intensity of the bands with low molecular weight

Summary

INTRODUCTION

Soy Protein Isolates (SPI) is the most highly refined soy products commercially available and represent the major protein fraction of the soy bean. Chemical modification has been developed to improve the functional properties of SPI and to promote its utilizations in food products (Babiker et al, 1998; Matemu et al, 2011). The quinones may react with cysteine, lysine, methionine and tryptophan residues in protein (Rawel et al, 2002, 2004). Chemical modification has been focused on an effective method to improve the functional properties of protein. Such interactions have not yet been emphasized enough for their role played in affecting the functional properties of SPI.

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION