Lower carotenoid concentrations in HPLC methods may also be explained by
saponification losses due to the relatively harsh conditions of alkaline
treatment. Especially the polar carotenoids are sensitive to such conditions. Although similar types of work have not been conducted in egg yolk it can be concluded for our results that the
observed underestimation in the HPLC method might be due to one or the other mentioned reason. Finally, some unidentified carotenoids present in the egg yolk are missed in the calculation
because of unknown chemical structure (no external standards available) or concentrations at detection level.