Enhanced Efficiency of Carotenoid Processing Utilizing Change in Physicochemical Properties Induced by Z-isomerization

Abstract

Carotenoids, the most common fat-soluble plant pigments in nature, have attracted considerable attention because of their powerful antioxidant activity and potential to prevent of various diseases, such as cancer and arteriosclerosis. These compounds have numerous geometric isomers owing to E/Z-isomerization at arbitrary sites of the multiple conjugated double bonds. However, in nature, most carotenoids are present in the all-E-configuration. (all-E)-Carotenoids are characterized by low solubility in solvents and high crystallinity. Thus, these characteristics result in the decreased efficiency of carotenoid processing, such as extraction and micronization. On the other hand, Z-isomerization of carotenoids induces change in physicochemical properties. For example, the solubility of carotenoids is markedly improved and they change from a “crystalline state” to an “oily (amorphous) state”. Utilizing these changes in physicochemical properties of carotenoids, we successfully improved the efficiency of carotenoid processing. The objective of this paper is to review the effect of Z-isomerization of carotenoids on the physicochemical properties and its application to carotenoid processing, such as extraction, emulsification, and micronization. Furthermore, aspects of Z-isomerization methods of carotenoids and effects of Z-isomerization of carotenoids on the bioavailability and bioactivity are also included in this review.