A Comparison and Extension of Methods for Carotenoids Detection in Green Vegetables Grown in Taiwan

This study examined several factors that affect the precision and accuracy of the quantitative determination of lutein, zeaxanthin, and fl-carotene. A modified and extended method for the analysis of carotenoids in green leafy vegetables was described. The procedure involves acetone extraction of carotenoids from a homogenized sample and saponification of the extract using a strong base resin (Ambersep 900 OH). Compared to the traditional protocol, Resin protocol reduced the analysis time from 4h to 1.5h, required less solvent and resulted in a higher recovery of carotenoids. In order to prevent oxidation of carotenoids, BHT was added in the beginning of extraction at a concentration of 0.1% (w/v) of solvent. The result also showed that fresh vegetables were superior to freeze-dried samples because the former had a higher extracting efficiency. A high amount of all transforms of lutein and n-carotene was found in sanchi, spinach, and Chinese kale.