Optimisation of egg yolk colour using natural colourants

The aim of this study was to obtain optimal egg yolk colour by replacing synthetic pigments with natural colour sources. The mixture design was applied varying the levels of marigold, carrot and paprika in the diet from 5 g/kg to 15 g/kg. Three hundred and sixty Lohmann Brown hens were divided into 12 dietary treatments with 6 replicates each. The coloration of the egg yolk was measured visually according to RYCF (Roche Yolk Colour Fan), lightness (L*), redness (a*) and yellowness (b*) were determined using the Minolta Chroma Meter, and content of beta-carotene was measured by spectrophotometer. Sensory analysis of acceptability, homogeneity and colour was performed by a panel of trained assessors. Principal Component Analysis was successfully used in discriminating of samples into treatment groups. Artificial Neural Network was developed for predicting colour and sensory parameters and showed high overall prediction accuracy (r(2) = 0.865). Significant differences in egg yolk colour between treatments were found. Treatments containing 10 g/kg marigold and 5 g/kg paprika; 5 g/kg marigold, 5 g/kg carrot and 5 g/kg paprika, or 10 g/kg carrots and 5 g/kg paprika were the most sensory acceptable and they had RYCF values of yolk colour, between 12.2 and 13.4.