Egg white matters: studying the role of genetic line and egg chilling storage on rheology of thick egg white and microstructure features supporting meringue.

Abstract

The thick white fraction of albumen (or egg white) is critical for maintaining the high quality and freshness of eggs during stor-age, but there is limited understanding of how storage affects the rheological behavior of this important gel. This study aimed toinvestigate the impact of egg storage time on the viscoelastic properties of the thick egg white (TKEW) fraction from two geneticlines (ISA-White (W) and ISA-Brown (B) hens), assessing the modification mechanisms through the analysis of microstructuralcharacteristics. Haugh units (HU) and foaming properties of albumen were also determined. Experiments were conducted afterlaying (Day 0) and after 15 and 30 days of egg chilling storage. The effects of storage duration on the TKEW viscoelastic propertiesdiffered between the W and B lines, causing an increase and a decrease in gel strength (a slope) of the W and B thick albumen,respectively. These findings, together with the microstructure analysis, indicated that after 30 days of storage, the W TKEWdeveloped a more elastic (lower loss factor, tan δ) but brittle (lower strain amplitude, γmax) albumen network structure, whereasthe B TKEW exhibited a weaker but much more deformable (higher γmax) structure. The textural properties of freshly made me-ringue batters containing chilled whole egg white (EW) presented similar behavior, supported by the microstructural featuresobserved in foams and batters. Additionally, the W TKEW showed higher HU, and the W EW produced a more stable foam (FS)during storage, although its foam capacity (FC) was lower than that of the whole albumen from the B genetic line