Relating the protein composition and air-water interfacial properties of aqueous flour extracts from wheats grown at different nitrogen fertilization levels

Abstract

Aqueous phase extractable proteins from wheat can play a functional role in foods requiring interfacial stabilization. We here investigated the (protein) composition of aqueous flour extracts from wheats grown at different nitrogen (N) fertilization levels and studied their air–water interfacial characteristics. An important finding was that α- and γ-gliadins were extracted from wheat flour with water, even to an extent that they in the present work comprised 62–71% of the extract proteins. Application of N fertilization during wheat cultivation led to flour extracts with higher foam stabilities and air–water interface dilatational moduli. In all cases, proteins were found to most likely be the dominant constituent at the air–water interface. Analysis of foam protein compositions revealed an enrichment of proteins with molecular weights matching those of α- and γ-gliadins. It thus seems that gliadins can to a large extent determine the foaming characteristics of aqueous wheat flour extracts.