The New York Times

August 29, 2007
Edible Films With Superpowers
By KIM SEVERSON

LEAVE heirloom tomatoesto the organic farmers and pork belly to the chefs. In the chemistrydepartment at Rutgers University and other laboratories like it, thereal action is in less trendy ingredients like oregano, crab shells andmilk.

In a handful of foodscience labs around the country, people who talk about food in terms ofmicrobes and polymers have been turning the natural pathogen fightersfound in everyday food into edible films and powders.

If their work pans out,thin films woven with a thyme derivative that can kill E. coli couldline bags of fresh spinach. The same material in powder form might besprinkled on packages of chicken to stop salmonella.

Strawberries could bedipped in a soup made from egg proteins and shrimp shells. Theresulting film — invisible, edible and, ideally, flavorless — wouldfight mold, kill pathogens and keep the fruit ripe longer.

For average eaters whoare still scratching their heads over trans fat, food coated withinvisible films that lure bad microorganisms to their death might aswell be nuclear fusion. But food scientists believe the potential forusing these everyday ingredients to make a safer food supply is huge.

“These natural films arereally a very hot topic these days,” said Michael Chikindas, a foodscientist working with the team at Rutgers. “The range of applicationsis endless, from very delicate foods to Army rations and spacemissions.”

On the most basic level,the films are something like a plastic wrap made of edible componentsthat dissolves in water. The films can be infused with molecules fromcloves, thyme or other foods that can keep unhealthy bacteria fromgrowing. They can even be manipulated to carry flavor.

Of course, what works inthe lab doesn’t always translate to the production line. As far as mostof the scientists know, these new edible antimicrobial films andpowders have yet to coat any food on the market. But their time isnear, researchers say. Patents are pending and several large companies,commodity groups and the federal government have invested money in theresearch.

In any food processinginnovation, the timing has to be right for both consumers andmanufacturers, and this might be the moment. Reports of food-bornesickness outbreaks have become part of the daily news. Just last week,baby carrots infected with shigella, a bacteria, were recalled in 12states. In July, 86 brands of canned chili sauce and other meatproducts were recalled in a botulism scare. In June consumers wereadvised to throw away bags of the snack called Veggie Booty aftersalmonella in it made people in 17 states sick.

As shoppers demand safer food, they’re also demanding healthier food made with ingredients they can pronounce.

“We’re working onconsumer-friendly antimicrobials, so people will read the package labeland not freak out,” said Mark Daeschel, a professor of food science atOregon State University.

Professor Daeschelteamed up with the food scientist Yanyun Zhao to engineer an ediblefilm made from a fiber found in crab and shrimp shells. They mixed inlysozyme, a protein found in both eggs and human tears that has proveneffective against listeria and staphylococcus. “It’s why we don’t geteye infections,” he said.

The result is a film that could coat fruit or meat or even become an edible yogurt lid.

Beyond concerns forsafer food and more natural products, the researchers are enjoyinganother bit of good timing: Consumers are becoming accustomed tothinking about edible film as a product that can deliver mouthwash andcough syrup. Why not food?

“One of the bigbreakthroughs were those Listerine strips,” said Tara McHugh, a foodresearcher with the Department of Agriculture who makes films fromcarrots and tomatoes. “Consumers have just become more comfortableeating films.”

Many people already eatmore films and coatings than they realize. The wax on apples and thecoating on aspirin are examples of edible protective layers used tobattle oxygen, moisture and mishandling.

Most coatings are madefrom gluten, cellulose, starch and various proteins approved by theFood and Drug Administration as safe for consumption. They line icecream cones and coat battered frozen food. A layer of film in somefrozen pizzas keeps moisture from the sauce from seeping into thecrust. Fresh sliced apples and other produce get coatings of ascorbicacid to keep them from turning brown.

Indeed, many shinyconfections like chocolate-covered almonds and raisins are coated withconfectioner’s glaze, a substance that might make some snackers cringe.It is often made with the secretions of a mite-sized beetle that livesin India and Thailand.

Makingconfectioner’s glaze also requires ethanol, which is regulated by theEnvironmental Protection Agency, said Dr. John Krochta, a foodscientist at the University of California at Davis. The new kinds ofedible coatings might eliminate the need for ethanol, he said.

In themid-1990s, when work on edible films was beginning to take off,Professor Krochta figured out how to turn whey into a film that wouldbe biodegradable. He was interested in the film, but also in finding away for cheesemakers to use the excess whey they produced. TheCalifornia government and that state’s dairy industry helped pay forthe research.

Now he isinvestigating whether his milk film can fight bacteria. The magicingredients are milk proteins designed to help protect calves frombacterial infections. He believes they could be manipulated so thatedible film wrapped around ready-to-eat turkey or smoked salmon wouldinhibit salmonella or listeria.

At Rutgers, researchers have just begun to dream about a product that could be used on food.

Ashley Carbone, agraduate student in Dr. Kathryn Uhrich’s chemistry lab, got togetherwith Dr. Chikindas from the food science department and started playingwith spice derivatives, sometimes filling the chemistry lab with thesmell of curry. Ms. Carbone discovered a way to synthesizebiodegradable polymers with oils from oregano, cloves or thyme. Thepolymers can then be turned into films or powders that, when applied tofood, can keep communities of bad bacteria from forming.

“We haven’t tried eatingit yet but I’m sure it’s going to be O.K.,” said Dr. Uhrich, whose teampresented her lab’s findings last week at the American ChemicalSociety’s annual meeting in Boston.

“It’s a naturallyderived polymer,” she said. “Even though I am a chemist, I recognizethat people are more comfortable with food-derived components.”

The films of Ms. McHugh,who works in the U.S.D.A. Agricultural Research Service labs near SanFrancisco, have a much less scientific beginning. She originallyintended to make films as way to get people to eat more fruits andvegetables. People liked the flavor and the novelty and they took off.A company called Origami Foods now wraps sushi in her carrot filminstead of nori and sells it at stores like Trader Joe’s. Her applefilm adds flavor and moisture to a spiral-cut ham.

As is often the case in the food science, one thing led to another.

“The next step is to get additional value out of them by adding some antimicrobials,” she said.

She’s playing aroundwith cinnamon, which would go nicely with her apple film and could workagainst listeria or salmonella, and oregano, whose oil contains thymoland carvacrol, which damage E. coli.

And unlike somewater-based films that are brushed on in liquid form, her sticky fruitand vegetable films might adhere to food better and provide alonger-lasting attack on bacteria.

Researchers are stillnoodling over several problems. One is how to control the timing of therelease of the natural bug fighters once the film is on the food.Others are the films’ excessive sensitivity to humidity, and how theycan be applied to food so that the good bacteria touch every surface.Then there are labeling issues. Are the milk and shellfish proteinsused in films the same ones that trigger allergic reactions? What aboutmilk films on products a vegan might eat?

And no one knows howmuch it might cost in additional research and new equipment to actuallytransfer films from a lab to a food plant.

But scientists say thefilms might be a more palatable way of killing pathogens thanirradiation, a process that has met resistance from food advocacyorganizations. And as excited as the scientists are about their newpowders and films, they are quick to point out that the products arenot cure-alls.