CAROTENOIDS IN CASSAVA - COMPARISON OF OPEN-COLUMN AND HPLC METHODS OF ANALYSIS

Cassava leaves and tubers from six cultivars were analysed for carotenoids by both open-column chromatography and high-performance liquid chromatography (HPLC). The major carotenoids of leaves were the non-vitamin A carotenoid lutein (86-290 mg kg-1 fresh weight (FW)) and the pro-vitamin A carotenoid beta-carotene (13-78 mg kg-1 FW). Immature leaves contained less than mature leaves. Tubers contained 0.1-3 mg kg-1 FW of beta-carotene and 0.05-0.6 mg kg-I FW of lutein. Carotenoids present in small amounts included alpha-, gamma-, and zeta- carotenes and beta-cryptoxanthin and others were separated and partially identified. Yellow tubers contain much more beta-carotene than white tubers and cassava is a good source of pro-vitamin A carotenoids compared with other root crops. Both methods gave similar results for beta-carotene and lutein, but the open-column method did not allow separation and quantitation of carotenoids present in small amounts. HPLC separated many carotenoids, but most peaks could not be identified for lack of reference compounds. A great advantage of open-column chromatography for developing countries is its use of simple equipment and readily available reagents and solvents compared with HPLC, which requires complex equipment needing careful maintenance and expensive solvents. The open-column method is more labour intensive but this is not a constraint in developing countries.