Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2003
Publication Date: July 5, 2003
Citation: Perkins Veazie, P.M., Collins, J.K., Edwards, A.J., Wiley, E.R., Clevidence, B.A. 2003. Watermelon: Rich in the antioxidant lycopene. Acta Horticulturae. 628:663-668.
Interpretive Summary: Lycopene imparts a red color to tomatoes, watermelon, and red grapefruit. This pigment has strong antioxidant properties, and consumption of lycopene-rich fruits has been implicated in reduced incidence of certain cancers. A study was done to determine how production practices and varieties influence the lycopene content of watermelon, and to determine how available lycopene from watermelon was in humans. Red-fleshed watermelons contained the most lycopene, and content was comparable to that of tomatoes (36 to 78 mg/kg fresh weight). Plasma levels of lycopene in humans after ingestion of watermelon juice (uncooked) or tomato juice (thermally processed) were similar, while almost no lycopene was found in the plasma of subjects held on a no-lycopene diet. These results indicate that watermelon contains substantial amounts of lycopene and that it is available to humans when consumed as a food.
Lycopene pigment provides the red color found in some plants, notably tomato and watermelon fruit. Lycopene is a highly efficient oxygen radical scavenger and has been implicated in many epidemiological studies as providing protection against cardiovascular disease and some cancers, particularly of the prostrate. Human uptake of lycopene from tomato-based products is thought to be more effective after heat and processing treatments. Watermelons contain as much or more lycopene than tomatoes but have been little studied as a source of lycopene. Over the last three years, we have conducted numerous studies with watermelon to determine maturity, storage, and minimal processing effects on lycopene levels. Additionally, a human clinical study with watermelon juice and tomato juice was done to determine lycopene uptake in humans. Watermelon cultivars exhibited a range of lycopene values, with seeded and seedless red fleshed types having 36 to 78 g/g lycopene, and orange or yellow watermelons had less than 5 g/g lycopene. Underripe and overripe melons had as much as 20% less lycopene than fully ripe melons, with maturity effects dependent on the variety. Storage of whole or cut melons for 2 to 10 days reduced lycopene by 6 to 10%. Assays of human plasma after lycopene ingestion indicate that lycopene was as efficiently obtained from watermelon juice as from tomato juice. Thus, watermelon fruit contains considerable lycopene, the pigment is maintained effectively in germplasm and with postharvest handling. Human uptake of lycopene from fresh watermelon juice was as efficient as that from a heated and processed tomato juice.