Fresher Finer Foods
by Judy Purdy

With names like hydroxypropyl methylcellulose, edible food coatings may not sound very appetizing. But thanks to Manjeet Chinnan's research, you may find them quite palatable indeed.

The UGA food science and technology professor has shown that edible films reduce spoilage by keeping fruits and vegetables fresh longer. His research proves they can increase the shelf life of foods like roasted peanuts by as much as 60 percent.

And for the growing number of Americans fighting the battle of the bulge, the news is even more appetizing. In two studies to be published later this year in the Journal of Food Science and the Journal of Food Engineering, Chinnan's research team has shown that edible films can reduce the amount of fat in fried foods.

In tests on fried chicken strips, Chinnan tried a variety of coatings - all of which are derived from plants - and found that some reduce fat absorption by more than a third. The coated chicken also proved moister.

Chances are, you already may have eaten some of the coating ingredients that Chinnan tests. They are used to thicken, coat, bind or gel everything from sausage and salad dressing to ice cream and beer.

"People in Asia have been using rice and soybean starches and proteins for centuries," Chinnan said. "They use wrappers made from such ingredients to hold the shape of jellied candies as well as to prevent stickiness."

Chinnan is not just containing and/or wrapping foods for freshness and reduced fat absorption. He also is developing and characterizing new films and coatings that have additional functional properties, such as controlling the migration of gases and lipids.

Many of the transparent coatings Chinnan uses in his research have little or no taste of their own, so they don't interfere with the flavor of the foods they protect. And because the coatings usually are made from plants, they could lead to more environmentally friendly packaging of food products, Chinnan said.

"The biggest challenge has been working with meats because the films are in a [water-based] solution and it takes time for them to evaporate," he said. "We don't want to leave the meat at room temperature because of microbial reasons, and meats don't dry as well when cold." So it was a boon when Chinnan's team discovered that, for frying meats like chicken, edible coatings work best when mixed directly with batter instead of being applied beforehand.

With a team that includes postdoctoral fellows, graduate students and visiting scientists from other nations, Chinnan also is finding ways to use coatings to keep frying oils fresher. When food is fried, fat and acids in the food or its marinade - things like vinegar and lemon juice - migrate to the oil, causing it to break down. The edible coatings create a barrier to these ingredients and enhance the oil's shelf life, Chinnan said.

His group also is experimenting with a peanut protein coating they make in their lab. "It's not very easy to make because of the nature of protein," he said. "Proteins are not easy to handle; they are fragile. But maybe by combining them with some other material we can increase their stability and enhance their physical properties."

The UGA food scientists also are interested in engineering films with properties that could deliver other benefits, such as transferring flavors to foods, adding health-promoting vitamins or using anti-microbial agents to reduce surface contamination of produce.

Future research will be devoted to determining which films are most cost-effective, Chinnan said. "Currently we are trying to optimize films and coatings, not only the types of films but also the quantity to apply. Ultimately my goal is to have increased food choices with added value and safety for consumers."

for more information, E-mail chinnan@cfsqe.griffin.peachnet.edu.