Functional, nutritional and conformational changes from deamidation of wheat gluten with succinic acid and citric acid

Changes in deamidation degree, hydrolysis degree, nitrogen soluble index, the foaming and emulsification properties, the tertiary and secondary conformation and nutritional property of wheat gluten deamidated with succinic acid and citric acid were identified. Succinic acid and citric acid were found to effectively deamidate the amides in wheat gluten proteins into carboxyl groups, which resulted in a significant increase of the nitrogen soluble index of wheat gluten. Deamidation of wheat gluten by succinic acid was found to be more efficient than that with citric acid, although wheat gluten treated with succinic acid exhibited less improvement in the foaming capacity and stability and experienced inhibition in the emulsification activity compared with the gluten treated with citric acid. Wheat gluten deamidated with citric acid exhibited more flexible protein molecules, greater changes in the tertiary and secondary structures and better nutritional characteristics. These results may be useful to the food processing industry. (C) 2010 Elsevier Ltd. All rights reserved.