Carotene and Novel Apocarotenoid Concentrations in Orange-Fleshed Cucumis melo Melons: Determinations of β-Carotene Bioaccessibility and Bioavailability

Muskmelons, both cantaloupe (Cucumis melo Reticulatus Group) and orange-fleshed honeydew (C. melo Inodorus Group), a cross between orange-fleshed cantaloupe and green-fleshed honeydew, are excellent sources of beta-carotene. Although beta-carotene from melon is an important dietary antioxidant and precursor of vitamin A, its bioaccessibility/bioavailability is unknown. We compared beta-carotene concentrations from previously frozen orange-fleshed honeydew and cantaloupe melons grown under the same glasshouse conditions, and from freshly harvested field-grown, orange-fleshed honeydew melon to determine beta-carotene bioaccessibility/bioavailability, concentrations of novel beta-apocarotenals, and chromoplast structure of orange-fleshed honeydew melon. beta-Carotene and beta-apocarotenal concentrations were determined by HPLC and/or HPLC-MS, beta-carotene bioaccessibility/bioavailability was determined by in vitro digestion and Caco-2 cell uptake, and chromoplast structure was determined by electron microscopy. The average beta-carotene concentrations (mu g/g dry weight) for the orange-fleshed honeydew and cantaloupe were 242.8 and 176.3 respectively. The average dry weights per gram of wet weight of orange-fleshed honeydew and cantaloupe were 0.094 g and 0.071 g, respectively. The bioaccessibility of field-grown orange-fleshed honeydew melons was determined to be 3.2 +/- 0.3%, bioavailability in Caco-2 cells was about 11%, and chromoplast structure from orange-fleshed honeydew melons was globular (as opposed to crystalline) in nature. We detected beta-apo-8'-, beta-apo-10', beta-apo-12'-, and beta-apo-14'-carotenals and beta-carotene than cantaloupe. The bioaccessibility/bioavailability of beta-carotene from orange-fleshed melons was comparable to that from carrot (Daucus carota).