Wheat Bread Supplemented with Egg Albumin: Structural Features, and In Vitro Starch and Protein Digestibility

This study aimed to explore the effects of egg albumin protein addition (5, 15 and 20 g/100 g db) on the textural characteristics, as well as in the in vitro digestibility of protein and starch of wheat bread. Egg albumin addition resulted in smoother bread loaves as compared to traditional wheat bread. Reduced hardness and increased cohesiveness were correlated to the protein secondary structure, mainly with the content of β-sheets. The in vitro protein digestibility decreased with the albumin addition, suggesting the mediation of protein-starch interactions. The in vitro starch digestibility was also decreased, reflected in a huge decrease of the slowly digestible starch fraction, but with non-significant changes in the rapidly digestible starch fraction. The supplemented albumin can form a physical barrier around the starch granules, which hampers the access of the amylolytic enzymes to the starch chains. Overall, the results of this study suggest that the addition of egg albumin is a viable alternative for producing wheat bread with reduced glycemic index and improved nutritional properties.