The structure, antioxidant and antibacterial properties of thiol-modified soy protein isolate induced by allicin

This study investigated the effect of allicin binding on the structure, antioxidant and antibacterial properties of soy protein isolate (SPI). Results showed that allicin bound to 82.6 % free thiol groups of SPI at a molar ratio of 0.5. The combination of allicin and SPI significantly affected the structure of protein. Result of circular dichroism showed that the content of α-helix decreased by 26.9 % and the content of β-sheet increased by 12.2 % over control when the molar ratio was 0.5. The result of surface hydrophobicity signified the unfolding of SPI with the action of allicin. These results implied that allicin binding might be a suitable method for the modification of SPI. Furthermore, the antibacterial and antioxidant experiments indicated that allicin-SPI conjugates not only had the capacity to inhibit the growth of Escherichia coli and Staphyloccocus aureus, but also had DPPH and ABTS radicals scavenging activities.