Edible coatings for ready-to-eat fresh fruits and vegetables

The use of edible films likely will expand dramatically in the future — especially for fruits and vegetables

The scientist who turned fresh-cut apple slices into a popular convenience food, available ready-to-eat in grocery stores, school cafeterias and fast-food restaurants, today described advances in keeping other foods fresh, flavorful and safe for longer periods of time through the use of invisible, colorless, odorless, tasteless coatings.

The overview of these edible films was part of the 246th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society. The meeting, which continues through Thursday in the Indiana Convention Center and downtown hotels, features almost 7,000 presentations on advances in science and other topics.

Attila E. Pavlath, Ph.D., pointed out that the use of edible films has grown dramatically since the mid-1980s, when only 10 companies were in the business, to more than 1,000 companies with annual sales exceeding $100 million today. Ready-to-eat fruits and vegetables now account for about 10 percent of all produce sales, with sales exceeding $10 billion annually. The use of edible films likely will expand dramatically in the future — especially for fruits and vegetables — as health-conscious consumers look for more foods that require minimal preparation like cut fruit and premixed salads, he noted.

“Fruits and vegetables have skins that provide natural protection against drying out, discoloration and other forms of spoilage,” Pavlath explained. He is with the U.S. Department of Agriculture’s Western Regional Research Center in Albany, Calif. “Cutting and peeling remove that natural protection, allowing deterioration and spoilage to begin. It’s visible within minutes for foods like apples and bananas, but occurs without any outward sign for other fruits and vegetables. Nature is a very good chemist and we are learning from that and sometimes improving on it with new edible coatings that protect the quality and nutritional value of food.”

Those coatings consist of a thin layer of edible material applied to the surface of a food product to preserve freshness. Apples, for instance, lose some of their natural wax coating during washing after harvest. The replacement is a thin layer of carnauba wax, obtained from the leaves of palm trees. That wax also gives sugar-coated chocolate candy an appealing gloss. Other common edible coatings include starch, alginate, carrageenan, gluten, whey and beeswax.

Pavlath and his group invented the technology that enabled schoolchildren and other consumers to enjoy a new apple treat — refrigerated, packaged apple slices that last 2-3 weeks without turning brown or losing crispness. Apples ordinarily begin to turn brown within 30 minutes after cutting or peeling. Pavlath’s process involves treating freshly cut apple slices with a form of vitamin C, resulting in the first commercial product that retains the desirable characteristics of fresh apples without leaving a detectable residue.

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