Zeaxanthin is a carotenoid produced by plants and has been associated with protection of the photosyn-
thetic machinery under light stress and, together with lutein, in protection of the central retina of the eye.
Zeaxanthin levels in blood plasma have been negatively correlated to the development of AMD (age-
related macular degeneration) (Gale et al., 2003). Under normal conditions, plants have a low content
of zeaxanthin. The aim of this study was to increase the zeaxanthin content in green vegetables by post
harvest treatments. Efficient conditions for activation of the endogenous enzyme system generating zea-
xanthin was established and included incubation at low pH (2.5–5.5), with the membrane permeable ace-
tic acid/acetate buffer at room temperature or above for 30 min or more. Typically more than 20-fold
increase in zeaxanthin content was obtained for spinach, corn salad, parsley, basil, lemon balm and peas.
For spinach up to 4 mg/100 g fresh weight of leaves were obtained. In consequence less amount of veg-
etables would be needed in the diet to provide the same amount of zeaxanthin for the eye.