Effects of Heating and Illumination on Trans−Cis Isomerization and Degradation of β-Carotene and Lutein in Isolated Spinach Chloroplasts

Publisher Website
Google Scholar
Abstract
The influence of thermal treatment and light exposure on degradation and isomerization of the predominant carotenoids (lutein and β-carotene) occurring in green leafy vegetables was assessed. The effect of lipid addition on carotenoid stability was also evaluated. For the first time, the stabilities of pure carotenoids and chloroplast-bound carotenoids were compared. Besides degradation, heating caused carotenoid isomerization in all samples. Whereas pure carotenoids favor 13-cis isomers, in native chloroplasts and heated chloroplasts 9-cis isomers were predominant. Illumination of freshly prepared chloroplast isolates caused an initial increase in the level of lutein (9.6%) and β-carotene (29.8%), while pure carotenoids exhibited time-dependent degradation. The addition of lipids to chloroplast preparations had the reverse effects on the retention of both carotenoids after heating; isomerization was not significantly affected. It was demonstrated that carotenoid stability has to be evaluated for every individual pigment in its genuine environment. Stability data based on model systems (e.g., pure carotenoids) may not be transferred to complex food matrices without intensive investigation. Keywords: Spinach; chloroplast; β-carotene; lutein; trans−cis isomers; heat; illumination

This publication has 28 references indexed in Scilit: