Carotenoid composition and content of legumes, tubers and roots by HPLC

As part of a series of studies on the analytical and nutritional aspects of carotenoids and retinoids in foods, seventeen types of legumes and their products and 9 tubers and starchy roots were studied for their carotenoid composition and content by HPLC. All samples were saponified and subsequently chromatographed using a reverse-phase HPLC method previously developed in this laboratory in which carotenoids were separated isocratically on an octadecylsilane (C18) column using a ternary mixture of acetonitrile, methanol and ethyl acetate (88:10:2) as the mobile phase. Carotenoid peaks obtained were tentatively identified using 6 reference standards similarly chromatographed. The HPLC method used enabled the separation and quantitation of the major carotenoids present, namely, lutein, cryptoxanthin, lycopene, g-, a- and b-carotenes. For most of the legumes, the major carotenoids detected were b-carotene, lutein and cryptoxanthin. Lutein was found in all the legumes studied, and was clearly the major carotenoid in most of the legumes, followed by unidentified carotenoids, b-carotene and cryptoxanthi. The other carotenoids were encountered infrequently and at low levels. The starchy roots and tubers gave a different carotenoid composition from those obtained for the legumes: lycopene and b-carotene were detected in all the samples except in sago. There was no clear pattern of carotenoids present in the samples studied. Compared with the vegetables and fruits, the carotenoid concentration in legumes, tubers and roots were found to be much lower. None of the items studied can be said to be good sources of vitamin A. Nevertheless, they are still of nutritional import flee, if consumed in significant amounts.