Impact of casein and egg white proteins on the structure of wheat gluten‐based protein‐rich food

BACKGROUND There is a growing interest in texturally and nutritionally satisfying vegetable alternatives to meat. Wheat gluten proteins have unique functional properties but a poor nutritional value in comparison to animal proteins. This study investigated the potential of egg white and bovine milk casein with well‐balanced amino acid composition to increase the quality of wheat gluten‐based protein‐rich foods. RESULTS Heating a wheat gluten (51.4 g)–water (100.0 mL ) blend for 120 min at 100 °C increased its firmness less than heating a wheat gluten (33.0 g)–freeze‐dried egg white (16.8 g)–water (100.0 mL ) blend. In contrast, the addition of casein to the gluten–water blend negatively impacted firmness after heating. Firmness was correlated with loss of protein extractability in sodium dodecyl sulfate containing medium during heating, which was higher with egg white than with casein. Even more, heat‐induced polymerization of the gluten–water blend with egg white but not with casein was greater than expected from the losses in extractability of gluten and egg white on their own. CONCLUSION Structure formation was favored by mixing gluten with egg white but not with casein. These observations were linked to the intrinsic polymerization behavior of egg white and casein, but also to their interaction with gluten. Thus not all nutritionally suitable proteins can be used for enrichment of gluten‐based protein‐rich foods. © 2015 Society of Chemical Industry