DOI: 10.1094/CC-83-0472 |  VIEW ARTICLE

Production of Thiyl Radical on a Peptide Derived from Wheat Protein by Superoxide Anion Radical.

Yuka Miyamoto (1,2), and Kimio Nishimura (1,3). (1) Department of Food Science and Nutrition, Doshisha Women’s College of Liberal Arts, Kamigyo-ku, Kyoto, 602-0893, Japan. (2) Present address: Department of Home Economics, Shukugawa Gakuin College, 6-58 Koshikiiwa-cho Nishinomiya, 662-8555, Japan. (3) Corresponding author. Phone: +81-75-251-4214. Fax: +81-75-251-4289 or 4214. E-mail: <knishimu@dwc.doshisha.ac.jp> Cereal Chem. 83(5):472-477. Accepted April 10, 2006. Copyright 2006 AACC International, Inc.

In the current study, we examined the role of superoxide anion radical (O(^–)(2)) in the improvement of bread dough by L-ascorbic acid. Because of difficulties in detecting thiyl radicals in the presence of L-ascorbic acid, we replaced the latter with riboflavin, which produces O(^–)(2) upon photoactivation. Nitro blue tetrazolium dye confirmed that O(^–)(2) was produced in dough upon photoactivation of riboflavin. Electron spin resonance spectroscopy coupled with spin trapping showed that, in a solution containing riboflavin and the hydrolyzed gluten peptide (GP-1), thiyl radicals are produced upon photoactivation. Addition of superoxide dismutase but not catalase suppressed the production of thiyl radicals on GP-1. These results suggest that the O(^–)(2) produced during the oxidation of L-ascorbic acid in dough generates thiyl radicals on gluten proteins. This, in turn, would increase the production of interprotein disulfide bonds and result in an improvement in bread structure.