Edible coatings help preserve fruits and vegetables during their often long trek from the farm to your local produce stand.

To help improve these coatings, Agricultural Research Service scientists have applied for a patent for a new edible coating made of food-grade polyvinyl acetate. It is cheaper to use and more effective than shellac at preventing postharvest fruit decay without discoloring the fruit.

The new coating developed by researchers at the ARS Citrus and Subtropical Products Laboratory in Winter Haven, Fla., preserves and protects harvested fruit, without whitening, at a considerable savings. The coating can be applied to fruits and vegetables by dipping, spraying or brushing on.

Polyvinyl acetate is a synthetic polymer that is used as an ingredient in chewing gum. In addition to the polyvinyl acetate, the coating for fresh produce can include plasticizers, surfactants that aid coverage, gloss-enhancing additives, and other ingredients for specific uses, such as to coat candy and baked goods.

The new coating has several advantages over shellac, which slows fruit respiration and keeps the fruit firm. Shellac tends to whiten or “blush” when it is exposed to moisture. This often occurs when apples are moved from cold storage to a humid environment. Another problem is that citrus fruits and some apple varieties develop “off” flavors when coated with shellac. And the fact that shellac coatings are primarily composed of insect exudate has made them objectionable to some consumers.

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