Location: Food Quality LaboratoryTitle: Carotene and novel apocarotenoid concentrations in orange-fleshed Cucumis melo melons: determinations of beta-carotene bioaccessability and bioavailability Author
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2011
Publication Date: 3/18/2011
Citation: Fleshman, M.K., Lester, G.E., Riedl, K.M., Harrison, E.H., Kopec, R.C., S, N., Schwartz, S.J. 2011. Carotene and novel apocarotenoid concentrations in orange-fleshed Cucumis melo melons: determinations of beta-carotene bioaccessability and bioavailability. Journal of Agricultural and Food Chemistry. 59:4448-4454. Interpretive Summary: Melons are the most consumed fresh fruit in the U.S. based on lbs/capita and orange-fleshed melons are an excellent source of beta-carotene i.e. provitamin A (a critically essential human vitamin). But a thorough investigation of carotenes present in orange-fleshed melons and melon carotene human bioaccessibility/ bioavailability is yet to be determined. This study discovered a new group of carotenes: apocarotenoids, precursors of vitamin A, present in both orange-fleshed cantaloupe and honey dew melon fruits along with the main precursor of vitamin A: beta-carotene. The novel orange-fleshed honey dew melon had significantly higher dry weight and carotene concentrations vs. cantaloupe, but bioaccessibility of carotenes were similar for both melon types. Orange-fleshed melon types were comparable in their carotene human bioaccessibiltiy/ bioavailability, on a par with carrots, even though carrots have four-times more carotene. Our findings show the reasoning for melons having a more efficient carotene bioaccessibility/bioavailability is due to their chromoplasts (the plant structure which contains the carotenes) being fatty and globular making carotenes highly bioaccessible vs. carrot chromoplasts being hard and crystalline making carotene poorly bioaccessible. This new information is of importance to human nutritionists and to research plant physiologist/food scientists.
Technical Abstract: Muskmelons, both cantaloupe (Cucumis melo Reticulatus Group) and orange-fleshed honey dew (C. melo Inodorus Group), a cross between orange-fleshed cantaloupe and green-fleshed honey dew, are excellent sources of ß-carotene. Although ß-carotene from melon is an important dietary antioxidant and precursor of vitamin A, its bioaccessibility /bioavailability is unknown. We compared ß-carotene concentrations from previously frozen orange-fleshed honey dew and cantaloupe melons grown under the same glasshouse conditions, and from freshly harvested field-grown, orange-fleshed honey dew melon to determine ß-carotene ssibility/bioavailability, concentrations of novel ß-apocarotenals, and chromoplast structure of orange-fleshed honey dew melon. ß-Carotene and ß-apocarotenal concentrations were determined by HPLC and/or HPLC-MS, ß-carotene bioaccessibility/bioavailability was determined by in vitro digestion and Caco-2 cell uptake, and chromoplast structure was determined by electron microscopy. The average ß-carotene concentrations (Jg/g dry weight) for the orange-fleshed honey dew and cantaloupe were 242.8 and 176.3 respectively. The average dry weights per gram of wet weight of orange-fleshed honey dew and cantaloupe were 0.094g and 0.071g, respectively. The bioaccessibility of field-grown orange-fleshed honey dew melons was determined to be 3.2±0.3 percent, bioavailability in Caco-2 cells was about 11%, and chromoplast structure from orange-fleshed honey dew melons was globular (as opposed to crystalline) in nature. We detected ß-apo-8’-, ß-apo-10’, ß-apo-12’-, ß-apo-14’24 -carotenals and ß-apo-13-carotenone in orange-fleshed melons (at a level of 1-2% of total ß-carotene). Orange-fleshed honey dew melon fruit had higher amounts of ß-carotene than cantaloupe. The bioaccessibility/bioavailability of ß-carotene from orange-fleshed melons was comparable to that from carrot (Dacus carota).