Studies on Egg Yolk Pigmentation

THE evaluation of food color is a psychological problem of appeal and of sensitivity to attractiveness or to irritation. In the case of egg yolk color there exists an “optimal-yellow,” which must be “appetizingly pretty,” as determined by the “corruptible human eye” (Bitz, 1963). Consumer acceptability thus depends on visual impression, which is not always well correlated with chemical determinations of yolk pigment concentration, since: a) the human eye is not very sensitive to the darker shades of yellow (Sunde, 1962; Madiedo and Sunde, 1962; De Groote and Reyntens, 1963; Tagwerker et al., 1962; Völker and Bürke, 1964); b) the standard colorimetric method (A.O.A.C., 1960) is not sensitive to reddish pigments, which deepen the visual color of yolks (Carlson et al., 1961, 1964; Farr et al., 1961, 1962; Völker and Bürke, 1964; Bartov and Bornstein, 1964); and c) the color of the broken yolk is not the same as the …