Special bath will help honeydews arrive at market much sweeter

Friday, May 21, 1999 | 9:55 a.m.

Sweeter, more nutritious honeydew melons might be rolling onto grocery shelves soon -- thanks to a simple process that allows them to stay on the vine to full maturity, while remaining firm enough to withstand cross-country shipment.

Two USDA scientists have found that cooling melons in a water bath containing a special calcium-amino acid solution right after harvest slows the natural aging process.

"Calcium, found in the green tissue under the rind, moves to the seeds as the melon ages, which softens the rind and eventually leads to spoilage. The calcium bath puts more of the mineral into the rind, keeping it firmer longer. This not only increases shelf life, but also fortifies the fruit's calcium content," said Dr. Michael A. Grusak, a plant physiologist at the USDA/ARS Children's Nutrition Research Center at Baylor College of Medicine in Houston. Grusak and Dr. Gene Lester, an ARS Subtropical Agricultural Research Center scientist in Weslaco, Texas, developed the anti-aging bath.

"Honeydew melons are very perishable, which has forced growers to pick them several days prior to full maturity to allow for shipment," Grusak said. While early harvesting has helped extend the melon's shelf life, it's also made their purchase a hit-or-miss situation for consumers.

"Once picked, honeydew melons don't develop any further sweetness," he said. A fully mature melon has a "soluble solids" content of 12 to 15 percent, mostly in the form of fruit sugar. But to allow for shipping, honeydews are currently harvested with levels as low as 9 percent. That's why some honeydews can lack flavor and sweetness.

Because the calcium-containing solution can be added to water baths used to cool melons at harvest, it is an easy and inexpensive process for growers to adapt, Grusak said. Several U.S. growers are considering testing the process during the May to June melon harvest season this year. Once perfected, this could make "vine-ripened" honeydews available to consumers.

Honeydew melon is rich in vitamin C and potassium and already provides a fair amount of calcium, for just 60 calories. It also provides fiber and smaller amounts of other important vitamins and minerals.