Spices keep old spuds from sprouting.

Cinnamon, mint oil and thyme make foods taste better -- and they also keep potatoes fresher longer, according to new laboratory findings.

Left in storage, potaties tend to sprout. When they send up a green shoot, they soften, shrivel and eventually spoil. At the same time, their starches convert to sugars that darken during cooking, creating brown spots on french fries and potato chips. Synthetic chemicals can delay the sprouting, but researchers with the U.S. Department of agriculture have now developed a host of natural alternatives.

Oils extracted from peppermint and other plants seem to suppress the growth of the green shoots, says plant physiologist Steven F. Vaughn at the National Center for Agricultural Utilization Research in Peoria, Ill. And almonds, cinnamon, cumin and thyme contain aromatic aldehydes ad alcohols that destroy the potato eye--the growth spot where roots and stems form. Other cells in the potato survive, explains Vaughn, but they convert their starch to sugar more slowly.

These natural sprouting inhibitors also kill a fungus that causes dry rot in potatoes, he says, including a strain that has become resistnat to fungicides.

The USDA scientists found that washing and cooking remove all traces of the spices. They have applied for two patients on the use of these substances as sprouting inhibitors, says Vaughn, and at least one company is considering developing them.

He described the new laboratory findings last week at the annual meeting of the Potato Association of America in Spokane, Wash. The researchers say they now plan to try the sprout inhibitors on potatoes stored in large commercial bins.