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 for 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 minutes 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 to 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 larger 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.status: publishe