Determination of carotenoids in yellow maize, the effects of saponification, and food preparations

Maize is an important staple food consumed by millions of people in many countries. Yellow maize naturally contains carotenoids which not only provide provitamin A carotenoids but also xanthophylls which are known to be important for eye health. This study was aimed at 1) evaluating the effect of saponification during extraction of yellow maize carotenoids, 2) determining the major carotenoids in 36 genotypes of yellow maize by high performance liquid chromatography with a C30 column, and 3) determining the effect of cooking on the carotenoid content of yellow maize. The major carotenoids in yellow maize were identified as all‐ trans lutein, cis‐ isomers of lutein, all‐ trans‐ zeaxanthin, α‐ and β‐cryptoxanthin, all‐ trans β‐carotene, 9‐ cis β‐carotene and 13‐ cis β‐carotene. Extraction procedures without saponification showed a significantly higher yield than that obtained using saponification. In addition, cooking by boiling yellow maize at 100°C for 30 minutes increased the carotenoid concentration, while baking at 450°C for 25 min decreased the carotenoid concentrations by almost 70% as compared to the uncooked yellow maize flour. Therefore, yellow maize is a good source of provitamin A carotenoids and xanthophylls, the stability of maize carotenoids depends on cooking methods and no saponification is needed for analysis of maize carotenoids