Accumulation of All-trans-β-carotene and Its 9-cis and 13-cis Stereoisomers during Postharvest Ripening of Nine Thai Mango Cultivars

Accumulation of β-carotene during postharvest ripening of nine Thai mango cultivars was assessed after verifying extraction and high-performance liquid chromatographic quantification of the β-carotene stereoisomers for this sample matrix. No relevant trans−cis isomerization was induced by the analytical procedure. The vitamin A potential of mangoes was evaluated at different ripening stages unequivocally defined by a ripening index (RPIWB). Being rather stable throughout postharvest ripening, the cultivar-specific proportion of cis-β-carotene isomers ranged from 14 to 40% of the total β-carotene content. Subjected to the same postharvest ripening conditions, only the cultivars Kaew, Maha Chanok, Chok Anan, and Nam Dokmai #4 developed a bright yellow−orange mesocarp coloration at their fully ripe stage (RPIWB = 1.5−1.8, sugar−acid ratio ∼ 50), resulting in total β-carotene contents of 6544−11249 μg/100 g mesocarp dry weight (DW) and vitamin A values of 892−1573 retinol equivalents (RE)/100 g DW. Contrarily, poor-colored cultivars Mon Duen Gao, Rad, Kiew Sawoei, Okrong Kiew, and Okrong Thong reached total β-carotene contents of 1019−2195 μg/100 g DW and vitamin A values of 136−298 RE/100 g DW at comparable sugar−acid ratios. Exponential development of mesocarp color (hue angle, H°) and all-trans-β-carotene levels, respectively, with RPIWB was described for each cultivar, allowing good prediction of mesocarp color and vitamin A value at consumption ripeness. Keywords: β-Carotene stereoisomers; Mangifera indica L.; postharvest ripening; vitamin A value; color