Improvement of Functional Properties of Glutens Extracted from Two Iranian Wheat Varieties (Sardari and Mahdavi) Employing Chemical and Enzymatic Modifications

Proteins are not only considered as a nutritional source but also are responsible for a number of functional properties such as solubility, emulsification, foaming capacity and gel formation in food products. However, insolubility of the proteins (as can be seen in gluten) and therefore their insufficient functional properties have created some limita-tions for their incorporation in formulated foods. Studies have indicated that chemical and/or enzymatic modifications are potential ways to improve proteins functionality. In this study gluten was extracted from two wheat varieties, Sardary and Mahdavi, and then modified by deamidation, acylation (succuinylation and acetylation) as well as enzymatic hydrolysis. Functional properties such as solubility measured as nitrogen solubility (NSI), emulsifying capacity (EC), foaming capacity (FC) and stability (FS) as well as the electro-phoresis patterns of native glutens were studied and compared with those of chemically- and/or enzymatically-treated samples. Most modifications significantly increased NSI from 20 to more than 70% and EC up to 35%. A great increase was also evidenced in foaming capacity that increased from 80 ml of foam volume in native samples to about 180 ml of foam in all the treated samples; however, only deamidated samples had stable foam over the time. Electrophoresis patterns indicated that, among chemical modifica-tions, deamidation caused limited hydrolysis of gluten polypeptides while enzymatic hy-drolysis led to a pronounced reduction in the molecular weight of wheat gluten polypep-tides (less than 15 KD) of both varieties.