Reflectance Colorimetric Evaluation of Egg Yolk Pigmentation

Moderately pigmented yolks were diluted with pigment‐free yolks to provide a wide range of samples with which to compare standard beta carotene equivalents with excitation purity and luminous reflectance values obtained with a reflectance calorimeter. Pigmented yolks were also mixed with a white diluent for reflectance colorimetric comparisons. Correlation coefficients of beta carotene equivalents with excitation purity and luminous reflectance values were +0.906 and −0.874, respectively. The regression line for luminous reflectance was linear and for excitation purity was curvilinear. The white diluent (1:l ratio) resulted in significant reduction of the tendency of excitation purity to plateau for deeply pigmented yolks.