A comparison of egg white and egg yolk in gluten-free bread

Abstract

Gluten-free breads made with egg whites, two-thirds egg white to one-third egg yolk, two-thirds egg yolk to one-third egg white, or egg yolks, were evaluated through sensory and mechanical testing. Breads were also made with adjustments to the water content differences between egg whites and yolks. Unadjusted bread formulations made with higher percentages of egg whites were larger in volume (2.60 cm3/g) compared to breads made with all egg yolk (2.07 cm3/g). Breads with higher levels of egg whites also had more consistent cell structure (10.7 ± 1.65 cells/cm2 vs 8.1 ± 0.72 cell/cm2, respectively), were moister and less firm, and had greater springiness than breads with egg yolks. Differences at the air cell interface were observed in the protein/lipid interaction through fluorescence microscopy and may contribute to lower volumes. Differences observed above were diminished in adjusted formulas, but significant differences in multiple sensory and mechanical attributes still remained. Although water content is an important factor, the addition of egg whites contributes to significant differences compared to breads made with higher levels of egg yolks on several sensory, mechanical and structural attributes. This study quantitatively confirms the characteristics contributed to egg whites versus egg yolks in gluten-free breads.