Evaluation of egg yolk colour.

Bovskova H., Mikova K., Panovska Z. (2014): Evaluation of egg yolk colour. Czech J. Food Sci., 32: 213–217. We compare visual evaluation of yolk colour estimated by the usual method applying La Roche scale with spectrophotometric determination of β-carotene by AOAC method, and by new rapid analyser iCheckTM Egg photometr (Bio Analyt). The eggs under consideration were purchased on a current Czech market. The eggs originated from various countries and various types of breeding including some specialities. The yolk colour varied between the values of 4–13 of La Roche scale. The carotenoid content expressed as β-carotene measured by AOAC method varied between 11–87 mg/kg. The carotenoid content expressed as β-carotene measured with the analyser iCheckTM Egg photometr was lower and varied between 7.5–68.5 mg/kg. The correlation between the colour hue measured visually and the carotenoid content was not proved. Slovak eggs from cages which contained 28.3 mg carotenoids in 1 kg of yolk had the darkest yolks (value 13), Czech bio eggs which contained 20.2 mg carotenoids in 1 kg of yolk had the palest yolks (value 6). The highest content of carotenoids was found in eggs from home hen breeding (72.5 mg carotenoids in 1 kg of yolk) whose colour hue had the value of 10.