DETERMINATION OF BETA-CAROTENE AND OTHER HYDROCARBON CAROTENOIDS IN RED GRAPEFRUIT CULTIVARS

Liquid-liquid extraction sample preparation was employed with nonaqueous reverse-phase HPLC and photodiode array detection to separate and quantify lycopene, beta-carotene, zeta-carotene, phytoene, and phytofluene in newer red grapefruit cultivars. These cultivars contained appreciably higher concentrations of both visible and colorless carotenoids when compared to the Ruby Red cultivar. Lycopene and beta-carotene were found in highest concentrations in the Star Ruby cultivar. Mean lycopene (all trans) levels in descending order were Star Ruby (33-mu-g/g), Ray (21-mu-g/g), and Flame (7.9-mu-g/g). Lycopene levels in the comparison Ruby Red grapefruit were 2.9 (interior) and 1.6-mu-g/g (Indian River). Mean beta-carotene levels in decreasing order were Star Ruby (9.6-mu-g/g), Flame (8.6-mu-g/g), and Ray (7.0-mu-g/g). The comparison Ruby Red fruits were both 4.2-mu-g/g. These cultivars could serve as important dietary sources of beta-carotene.