Enzymatically Hydrolyzed Wheat Gluten as a Foaming Agent in Food: Incorporation in a Meringue Recipe as a Proof-of-Concept.

There is a growing interest in substituting animal proteins with plant protein sources in food systems. A notable example is the replacement of hen egg white (EW) protein, which is used in a wide range of food products because of its excellent foaming characteristics. Here, enzymatically hydrolyzed wheat gluten, which has greater solubility and better foaming properties than wheat gluten itself, was prepared and incorporated in a classical meringue recipe to investigate its potential as a foaming agent. Meringues based on gluten hydrolysates (GHs) had batters with lower density and greater apparent viscosity than those based solely on EW protein. Furthermore, after baking, these GH containing meringues had greater specific volume than those based on EW protein alone and no notable differences in color or texture between the different samples were noted. These outcomes were related to basic insights in the air-water interfacial behavior of GHs obtained in earlier studies. More specifically, the greater foaming capacity of GH than of EW protein solutions was related to their superior meringue batter (density and apparent viscosity) and product (specific volume) properties. While EW protein solutions had better foam stability than GH solutions (in the absence of sugar), this was apparently less relevant for meringue properties, probably due to the very high viscosity of the sugar rich batter, which could obscure differences in the intrinsic foam stabilizing ability of the samples. PRACTICAL APPLICATION: Replacing animal proteins with plant protein sources in the food industry is desirable from an economic and environmental perspective. Enzymatic hydrolysis serves as a tool to improve the foaming properties of water-insoluble wheat gluten proteins. We conclude that wheat gluten hydrolysates can be a valid functional alternative for egg white proteins in meringues, and possibly other food systems.