OCCURRENCE OF CIS-ISOMERS OF PROVITAMIN-A IN BRAZILIAN FRUITS

Brazil has a wide variety of tropical, subtropical, and temperate fruits with widely differing carotenoid compositions, providing a good setting for investigating the natural;occurrence of cis-isomers of provitamins. Seventy-five samples were analyzed. The fruits could be classified into two main groups: (1) those having beta-carotene as the principal provitamin and (2) those with beta-cryptoxanthin as the major provitamin. Some fruits also had alpha-carotene, gamma-carotene, alpha-cryptoxanthin, and beta-apo-10'-carotenal, usually at low levels. cis-Isomers were not found in caja, papaya (two cultivars), passion fruit, pitanga, and West Indian cherry. Traces of 13-cis-beta-carotene were found in some samples of loquat, mango (two cultivars), and piqui. Buriti, mamey, nectarine, and peach had 0.1-4.2 mu g/g 13-cis-beta-carotene and 0.1-1.0 mu g/g 9-cis-beta-carotene; the latter two fruits and piqui also had 0.2-0.4 mu g/g neo-beta-cryptoxanthin. Overestimations of only 3-10% of the retinol equivalents occurred when the isomers were not separated, indicating that this separation is not important in fresh fruits.