Source lycopene from watermelon.

There's no upstaging watermelon at a summer picnic. The much-loved fruit with its juicy red flesh is one of the best sources of lycopene, an antioxidant thought to guard against heart disease and some cancers.

Now, a chemist with the USDA-ARS has made it easier to access watermelon's source of lycopene. The researcher has come up with a way to gently extract the antioxidant from watermelon flesh and juice, ensuring it stays in its most natural form. The resulting lycopene can be processed into a powder, paste or liquid suitable for use as a nutritional supplement or food coloring. A patent covering the technique has been filed, and licenses are available.

Currently, most lycopene formulations are sourced from tomatoes--from the copious juice, skins and fleshy residue left over after processing the fruit. But fresh watermelon, which actually contains more lycopene than fresh tomatoes, ounce for ounce, is an ideal source of the powerful antioxidant.

With the new technique, growers would also have a potential new market for their imperfect melons. Each year U.S. watermelon growers must toss out up to 25% of their crop because the fruits don't make the grade. But despite their bruised, misshapen or discolored exteriors, these melons could be a valuable source of lycopene, since the fruit's outward appearance has no effect on its nutrient content.

The lycopene formulation researchers have discovered is unlike any currently available. That's because the extraction method respects the melon's cellular makeup. In the fruits and vegetables in which it is found, lycopene is naturally packaged in tiny structures called chromoplasts.

Scientists use a technique that does not injure these delicate organelles, or their thin, fragile membranes. They found that lycopene left inside its protective membrane is more stable and boasts a longer shelf life. The technique can also be used to tap the lycopene found in other fruits, including tomatoes, guava, rosehips and pink grapefruit.

Lycopene is one of about 600 carotenoids naturally found in plants, bacteria, fungi and algae. Like other carotenoids, such as lutein and B-carotene, lycopene plays dual roles in humans and plants as a free-radical scavenger and exhibits strong antioxidant properties in vitro.

Further information. Wayne Fish, USDA-ARS South Central Agricultural Research Laboratory, 911 E. Highway 3, Lane, OK, 74555; phone: [phone]; fax: [phone]; email: [e-mail].