Isomerization of carotenoids

Abstract

At room temp. solns. of chromatographically pure lycopene, [beta]-carotene or kryptoxanthin undergo partial isomeriza-tion as indicated by decrease of the colorimetric value and by displacement of the absorption maxima towards shorter wave lengths. The speed of this spontaneous isomerization, which tends towards an equilibrium, increases on heating. The interconversion is reversible. Partly isomerized solns. always give 2 distinct layers in the Tswett column composed of Ca(OH)2 or alumina. The phenomenon is not caused by the adsorption itself.