Nobody likes biting into an apple and getting a mouthful of mush.

Fortunately, that doesn't happen too often. The credit goes to a bunch of folks--apple growers, packers, inspectors, distributors and grocery store produce managers. They make sure we consumers get only the finest, crispiest apples.

But what of the soft apples, or those that don't "make the grade"? Some go to food processing plants for making juice or other tasty products like apple sauce. Still, a few mushy apples seem to find their way into mom's fruit basket.

Part of the reason is because distributors don't have a fast, gentle method of checking individual apples on their way to market, processing or storage. They can check a sampling of apples but not an entire harvest, something that sonic testing shoots for.

Puncture tests and tests that check an apple's sugar content, are destructive. And they can't be used more than once.

Consider also the sheer number of apples that distributors deal with. In 1994, for example, U.S. growers harvested about 11 billion pounds, worth about 1.5 billion dollars.

"Firmness," says Judith Abbott, a horticulturist, "is not sorted for right now. There's just no way to do it."