Disclaimer: Dr. E. Allen Foegeding served as Scientific Editor and Dr. Shridhar Sathe served as Associate Editor overseeing single-blinded review of this manuscript. It is the policy of JFS to blind Editorial Board members from the peer-review process of their own submissions, just as all authors are blinded.
C: Food Chemistry
Changes in Structural Characteristics of Antioxidative Soy Protein Hydrolysates Resulting from Scavenging of Hydroxyl Radicals
Article first published online: 17 JAN 2013
© 2013 Institute of Food Technologists®
Journal of Food Science
Volume 78, Issue 2, pages C152–C159, February 2013
How to Cite
Zhao, J., Xiong, Y. L. and McNear, D. H. (2013), Changes in Structural Characteristics of Antioxidative Soy Protein Hydrolysates Resulting from Scavenging of Hydroxyl Radicals. Journal of Food Science, 78: C152–C159. doi: 10.1111/1750-3841.12030
- Issue published online: 6 FEB 2013
- Article first published online: 17 JAN 2013
- Manuscript Accepted: 30 NOV 2012
- Manuscript Received: 20 MAY 2012
- hydroxyl radical;
- soy protein
Antioxidant activity of soy protein (SP) and its hydrolyzed peptides has been widely reported. During scavenging of radicals, these antioxidative compounds would be oxidatively modified, but their fate is not understood. The objective of this study was to evaluate the structural characteristics of SP hydrolysates (SPHs), compared to intact SP, when used to neutralize hydroxyl radicals (•OH). SPHs with degree of hydrolysis (DH) 1 to 5 were prepared with Alcalase. Antioxidant activity of SPHs was confirmed by lipid oxidation inhibition measured with thiobarbituric acid-reactive substances, ability to scavenge 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radicals, and ferrous ion chelation capability. Oxidation of SPHs was initiated by reaction with •OH generated from 0.1 mM FeCl3, 20 mM H2O2, and 1.0 mM ascorbate. After oxidative stress, carbonyl content of SPHs increased by 2- to 3-fold and sulfhydryl groups decreased by up to 42% compared to nonoxidized samples (P < 0.05). Methionine, histidine, and lysine residues were significantly reduced as a result of inactivating •OH (P < 0.05). Attenuated total reflectance-Fourier transform infrared and circular dichroism spectroscopy suggested the conversion of helical structure to strands and turns. Oxidatively modified SPHs had a lower intrinsic fluorescence intensity but similar solubility when compared to nonoxidized samples. These structural changes due to •OH stress may impact the ingredient interaction and functionality of SPHs in food products.