ARS makes melons more nutritious
to make melons more nutritious - by spraying them with potassium
while they are still growing on the vine.
Over the past 15 years, melons have seen the biggest leap in popularity of all fruits in the use. Consumption increased 23 percent between 1989 and 2004 to an annual average of 30 pounds per person. The retail value of the melon market, including imports, is estimated to be between $3 and $4 billion.
Cantaloupe and honeydew melons feature in the new food pyramid, MyPyramid, as possible fruits to include in the recommended daily five to nine portions of fruit and vegetables.
Both varieties already have an excellent nutritional profile, with a fourth of a medium-sized cantaloupe providing 400 percent of the daily recommended vitamin A and almost 100 percent of vitamin C.
An eighth of a honeydew is also a good source of potassium and vitamin C.
But Gene Lester, a plant physiologist in ARS' crop quality and fruit insects research unit, thought there was still room for improvement:
"If we can improve their quality," he said in the ARS magazine, "we can provide even more opportunities for melon growers to increase profits while adding nutritional value for consumers."
Lester's method involved spraying the leaves of the cantaloupe and honey dew melon plants with one of two food-grade compounds, a glycine-potassium mix or potassium chloride, once a week during the four to six week growing period, which takes place in spring or fall.
The compounds were absorbed through the plants' leaves and the skin of the fruit, and resulted in "greatly increased" levels of beta carotene in the harvested melons. It also boosted photosynthesis, which led to raised sugar levels and, as a result, higher levels of vitamin C.
The results, seen over two harvests in both greenhouses and on several acres of land, were slightly better with the glycine-potassium, but with both compounds the observed results were better than with no potassium at all.
Beta-carotene, the vitamin A precursor, is also known to be one of the most powerful antioxidant carotenoids and has been implicated in the prevention of a range of health conditions, including cancer and cataract.
By making melons sweeter - as much as 11 percent or so - Lester's research could lead to their being classified as a gourmet-type fruit, attracting the attention of high-end restaurants and buyers. What is more, the melons treated with potassium matured two to three days earlier.
On the costs side, the potassium formulations are quite inexpensive, as well as being readily available and safe. Lester also said that they could be combined with insecticide or sprays for disease.
Other investigations have indicated that applying calcium to melons on the vine can make them more resistant to disease and prolong shelf life, so growers may wish to consider combining the two for a longer-lasting, nutritious fruit.
