She says red pigment is important from a marketing standpoint.
"People like to eat red watermelon. They associate a pale-pink
color with unripe melon."
Davis, working with Perkins-Veazie and food technologist Julie Collins,
screened for sugar content in lines of watermelon, Citrullus lanatus,
provided by ARS's Southern Regional Plant Introduction Station's germplasm
bank. The station is run by ARS's Plant Genetic Resources Conservation
Unit in Griffin, Georgia, in cooperation with the Southern Agricultural
The team grouped melons into "red" and "pink" categories
and compared the TSS values to color development. Among their findings:
of 77 red watermelons, 7 had a TSS of less than 6 percent, which Davis
considers low. Of 80 pink melons tested, 33 had a TSS below 6 percent.
"This shows that pigment production can occur without high TSS
production," she says. "We even found red pigmented fruit
with a TSS content as low as 3.1 percent."
Next was development of a commercially acceptable, low-sugar, high-pigment
watermelon that consistently produces flavorful fruit. "We have
a line that produces crisp, red-fleshed watermelon with a TSS content
of around 5 percent," she says. "But it's not ready for commercial
production, since it does not yet express consistent flesh color. Further
selection is required."
Mini-Melons for Your Lunch Bag
Meanwhile, Perkins-Veazie investigated the nutritional aspects of mini-watermelons,
which are about 6 inches in diameter and weigh between 3 and 7 pounds.
They are seedless, have a thin rind, and offer uniform flavor throughout.
They've been commercially available for about 2 years.
"They're a new option," she says. "You don't have to
slice a watermelon up anymore to carry it with you. You can take one
along for lunch and slice it open there."
Her team tested 15 lines of mini-watermelons already on the market
and discovered that the fruits are chock-full of lycopene and beta-carotene.
Average lycopene concentrations of the 15 lines ranged from 6,700 to
9,600 micrograms per 100 grams (µg/100 g), with several varieties
scoring higher lycopene levels than previously reported for conventional
large seeded and seedless watermelons. Those ranged from 3,700 to 6,900
"Also, two varieties were unusually high in beta-carotene, with
averages of 1,100 to 1,400 µg/100 g," says Perkins-Veazie.
"Full-sized seeded melons usually have about 300 µg/100 g."
She stresses that all mini-melon lines are the result of natural breeding
and that genetics is probably the biggest factor in her results. "It
wouldn't be right to say that mini-melons just naturally have higher
lycopene and beta carotene contents than larger melons. But we've shown
that the mini-melons on the market are high in these important nutrients,
and that's just another characteristic that consumers will like."
Future research will focus on methods of extracting lycopene from watermelons
for use in dietary supplements or food colorants. "With all these
exciting changes, watermelon is not just for picnics anymore,"
Sam Pair, the laboratory's research leader, agrees. "I have in
my office an experiment station bulletin more than 100 years old that
states watermelon has no other use than as a sweet treat. That concept
has been thoroughly dispelled. We are only beginning to scratch the
surface regarding the health benefits and potential value-added products
watermelon can provide."By Luis
Pons, Agricultural Research Service Information Staff.
This research is part of Plant, Microbial, and Insect Genetic Resources,
Genomics, and Genetic Improvement (#301) and Quality and Utilization
of Agricultural Products (#306), two ARS National Programs described
on the World Wide Web at www.nps.ars.usda.gov.
Angela R. Davis and
Penelope M. Perkins-Veazie
are with the USDA-ARS South Central
Agricultural Research Laboratory, Hwy. 3 West, Lane, OK 74555-0159;
phone (580) 889-7395, fax (580) 889-5783.
"A New World of Watermelon" was published in the December
2004 issue of Agricultural Research magazine.