Calcium Bath Keeps Melons Fresh Longer

Dunking melons in special calcium solution right after harvest prolongs fruit freshness up to two weeks beyond the normal shelf life of seven to 12 days, Agricultural Research Service scientists report.

Longer melon shelf life is good news for consumers, given that per capita melon consumption in the U.S. reached new highs in the 1990's, thanks largely to sweeter, more nutritious varieties. Now the calcium treatment may further boost melon consumption by paving the way for extensive marketing of vine-ripened fruit.

Aging melons--especially the tissue associated with the rind--need calcium to maintain firmness that protects against spoilage. But calcium in the tissue becomes depleted as it steadily migrates to the seeds.

ARS plant physiologists in Weslaco and Houston, Texas, first studied greenhouse-grown melons to find concentrations of an amino acid-calcium chelate solution that might curb the migration loss without harming the fruit. Then, in experiments begun last spring, they submerged field-grown melons for 20 minutes in solutions of up to 4 grams of calcium per liter.

With technology for extending melons’ shelf life, growers of recently developed hybrid honeydews may find marketing of vine-ripened fruit a more attractive option partly because it will become easier to comply with a federal harvesting law. It stipulates that melons destined for interstate commerce can be harvested when 9 percent of the fruit consists of solids that can be dissolved in water. When ripe hybrid melons detach themselves from the vine, their soluble solids contents typically range from 12 to 15 percent, almost totally in the form of sugars.

An article about the calcium treatment appears in the February issue of Agricultural Research magazine. The article also is online at:

/is/AR/archive/feb99/melon0299.htm

ARS is the chief research agency of the U.S. Department of Agriculture.

Scientific contact: Gene E. Lester, ARS Crop Quality and Fruit Insect Research Unit, Weslaco, Texas; phone (956) 565-2647, fax (956) 565-6652, glester@pop.tamu.edu; and Michael A. Grusak, ARS Children’s Nutrition Research Center, Houston, Texas; phone (713) 798-7044, fax (713) 798-7078, mgrusak@bcm.tmc.edu.