Pigmentation of White, Brown, and Green Chicken Eggshells Analyzed by Reflectance, Transmittance, and Fluorescence Spectroscopy

Abstract

We report on the reflectance, transmittance and fluorescence spectra ( λ =200–1200 nm) of four types of chicken eggshells (white, brown, light green, dark green) measured in situ without pretreatment and after ablation of 20–100 μm of the outer shell regions. The color pigment protoporphyrin IX (PPIX) is embedded in the protein phase of all four shell types as highly fluorescent monomers, in the white and light green shells additionally as non‐fluorescent dimers, and in the brown and dark green shells mainly as non‐fluorescent poly‐aggregates. The green shell colors are formed from an approximately equimolar mixture of PPIX and biliverdin. The axial distribution of protein and colorpigments were evaluated from the combined reflectances of both the outer and inner shell surfaces, as well as from the transmittances. For the data generation we used the radiative transfer model in the random walk and Kubelka‐Munk approaches.

Mitochondrial transcription factor A induces the declined mitochondrial biogenesis correlative with depigmentation of brown eggshell in aged laying hens

“…Brown, blue, white, and tinted eggshells contain 2 major pigments, protoporphyrin IX ( Pp IX ) and biliverdin ( Bv ) ( Ostertag et al., 2019 ). Blue eggshells contain a large amount of Bv, which is formed from the decomposed heme ( Zhang et al., 2019 ) and have antioxidative activities toward free radicals and reactive oxygen species ( Hargitai et al., 2016 ).…”

“…Blue eggshells contain a large amount of Bv, which is formed from the decomposed heme ( Zhang et al., 2019 ) and have antioxidative activities toward free radicals and reactive oxygen species ( Hargitai et al., 2016 ). Brown, white, and tinted eggshells are rich in Pp IX ( Ostertag et al., 2019 ), which exhibits antibacterial activity as a protector on the egg surface ( Ishikawa et al., 2010 ). The concentration of Pp IX has been reported to be positively correlated with antibacterial protein contents of the albumen ( Javůrková et al., 2019 ) and cuticle ( Mikšík et al., 2014 ).…”

Expanding the eggshell colour gamut: uroerythrin and bilirubin from tinamou (Tinamidae) eggshells

“…Thus, tinamous have access to an expanded eggshell pigment colour palette. Furthermore, since this two-pigment model, which assumes an even mixing of the pigments throughout the pigmented layer, achieved a close match to the experimental eggshell colours, it also indicates that none of the additional mechanisms discovered to modulate eggshell colours-such as uneven distribution of the pigments throughout the cuticle and eggshell [46][47][48] , colour modulation by the cuticle and eggshell structure 2,3 , pigment aggregation 49 , or the strongly solvatochromic properties and conformational plasticity of linear tetrapyrroles 30,[50][51][52] that might express different hues in variable protein matrices-play a prominent role here. Likewise, the much less deeply yellow-coloured dipyrrins present also do not play any major role in the coloration of the eggshells.…”

Evaluation of Calcium Carbonate Content in Eggshells of Avian, Turtle, Snail, and Ostrich Using Chemical Analysis and Scanning Electron Microscopy

“…The shells of eggs are the perfect complex bio-mineral that superposes functionality, mechanical stiffness, and aesthetic appearance and contains all that an embryo requires for safe development through to hatching in harsh environmental conditions. The chicken eggshell mainly consists of calcium carbonate (95% w/w), hydroxyapatite crystals (1% w/w) in the outermost calcified layer of the chicken eggshell, organic matrix (2 % w/w of the palisade layer), pigments as colorants (0.15-1200 nmol/g) and more than 10% (v/v) void cavities with about 0.4% (w/w) of adsorbed water [1], [2]. The surface of the inner shell consists of two membranes followed by interstitial calcite columns, a so-called mammillary layer that is a regular array of cones, each with a core of concentration of organic matter that had been described as neutral mucopolysaccharide [1].…”