Influence of Pasteurization, Spray- and Freeze-Drying, and Storage on the Carotenoid Content in Egg Yolk

A liquid chromatography−atmospheric pressure chemical ionization mass spectrometry [LC-(APCI)MS] method was developed to identify and quantify the carotenoids present in fresh, pasteurized, and freeze- and spray-dried egg yolk in two independent batches. The egg yolk powders in each batch were stored in the dark for 6 months at −18 or 20 °C. Carotenoids were isolated by solvent extraction without saponification and analyzed by HPLC using a C30 column coupled to a photodiode array and mass detector. The most abundant carotenoids were all-E-canthaxanthin, all-E-lutein, all-E-zeaxanthin, 9-Z-canthaxanthin, and β-apo-8′-carotenoic acid ethyl ester. Pasteurization of the egg yolk caused no critical changes in the carotenoid content. On the contrary, drying to a dry matter of 98−99% led to higher carotenoid contents, induced by a denaturation of binding proteins, and a destabilization of the cell matrix. After the 6 months of storage, the contents of all main carotenoids in the egg yolk powder were significantly lower. The synthetic carotenoids canthaxanthin and β-apo-8′-carotenoic acid ethyl ester showed a higher retention rate, and the greatest losses occurred within the first 8 weeks. Statistical tests (ANOVA, P < 0.05) also proved that after 26 weeks, the egg yolk powders stored at −18 °C showed only a slightly higher retention of carotenoids when compared to the powders stored at 20 °C.