Pigmenting Efficacy of Several Oxycarotenoids on Egg Yolk

Abstract

This experiment was conducted to test the influence of three dietary sources of yellow (YEW) and two sources of red (RED) oxycarotenoids when combined at two different YEW to RED ratios (a 3x2x2 factorial arrangement of treatments) on egg yolk color. Pigmentation was measured visually by the Roche color fan (RCF) and by reflectance colorimetry using a Minolta CR-300 colorimeter. Source of YEW, RED, and YEW:RED ratio influenced yolk pigmentation. Beta-apo-8’-carotenoic acid ethyl ester pigmented the yolk more efficiently than either of two natural saponified marigold extracts. A natural saponified marigold extract rich in zeaxanthin obtained by isomerization pigmented the yolk better than a standard saponified marigold concentrate. Canthaxanthin pigmented the yolk better than a natural saponified red pepper extract. A YEW:RED ratio of 8:4 improved pigmentation over a ratio of 12:3 (RCF of 13.3 and 12.9, respectively; P<.001). The ratio of redness to yellowness obtained by reflectance colorimetry gave scores similar to those obtained by RCF. Thus, industry use of RCF or reflectance colorimetry to evaluate egg yolk color will yield indistinguishable results in practical application.