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Playing with Food

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An OSU scientist fights food-borne disease with a surprising collection of natural ingredients.

Mark Daeschel likes playing with food.

Whether he’s making disinfectant from wine, zapping water to fight bacteria or transforming raisins into preservatives, this Oregon State University food science professor finds weird and wonderful ways to conquer food-borne disease and keep our food supply both safe and tasty.

While traditional food safety methods rely mostly on chemical preservatives to combat disease microbes, Daeschel searches for natural ingredients that do the same thing. By looking in the least likely places, Daeschel is finding effective, and surprising, alternatives to chemicals. His approaches are revolutionizing the food industry by providing alternative uses for foods while cutting production costs. It’s no wonder he has five patents under his belt.

Food production is inherently risky—even tiny water droplets can invite microbial contamination.

“We’ve used chemical preservatives in the past because they work well to keep food from spoiling,” Daeschel says. “Now our strategy is to use a series of obstacles that will cumulatively wear down microbes without using chemicals and without affecting the quality of the food product.” Simple treatments such as heating slightly or decreasing moisture content can stress microbes and inhibit their growth. Natural antimicrobials, Daeschel’s specialty, can provide a final blow.

But microbes constantly evolve. And so do society’s tastes and preferences. “You really have to understand the food system to develop a good antimicrobial,” says Daeschel. And you’ve got to know your microbes. As the former Nor W’ester Chair in Fermentation at OSU, Daeschel knows microbes. He spent much of his early career focused on the lactic acid bacteria involved in the preservation and fermentation of beer and wine. As the increasing number of food safety challenges piqued his interest, he began to probe the hidden talents of microbes already used in food production.

In particular, Daeschel was intrigued by a group of bacterial proteins, called bacteriocins, that have the ability to destroy bacteria. He knew that one well-studied bacteriocin called nisin attacks bacteria that can cause deadly outbreaks of food poisoning, such as botulism and listeria. Searching for new uses, Daeschel and colleagues found that coating food processing equipment with nisin can help prevent microbial spoilage. He found that nisin, as well as an enzyme called lysozyme, which occurs naturally in egg whites, can function as effective natural preservatives in beer and wine.

Man spraying a glass table. Colorful bottles and sprayers.

Daeschel began to test wine's ability to fight microbes, developing a disinfectant with a spritz of chardonnay. Photo: Lynn Ketchum

 

Finding new uses for seemingly useless products, OSU’s Mark Daeschel transformed surplus wine into a household disinfectant. Photo: Lynn Ketchum

“Lysozyme breaks down the cell walls of bacteria, chews them up and digests them,” Daeschel said. He estimates that 25 percent of the wine industry now uses lysozyme to prevent bacterial spoilage.

After years of screening microbes, Daeschel and his colleagues discovered a new bacteriocin called Plantaricin W, which has the potential to replace sulfites in wine fermentation. The new bacteriocin conducts the right kind of fermentation to create wine and inhibits the growth of spoilage bacteria.

From studying ways to fight microbes in wine, Daeschel turned his attention to exploiting the inherent antimicrobial properties of wine itself. He thought there might be a grain of truth in the old adage from seasoned travelers that sometimes it’s safer to drink the wine than the water. It seems that wine drinkers, compared to teetotallers, rarely suffer from food poisoning. To test this observation, Daeschel created a fake stomach out of plastic tubes and bags and set it to digesting a mixture of food, wine and synthetic gastric juices. The model gave Daeschel a way to measure what would happen when he added the pathogen Salmonella to the mix. Salmonella is a leading cause of food poisoning, but it didn’t stand a chance when it was added to the model stomach containing wine. It seems that the wine’s natural acids, coupled with its alcohol content, gave disease organisms the “one, two” punch.

If wine worked so well in the human stomach, Daeschel thought, how would it work on the kitchen sink? He began to test wine’s ability to fight microbes, developing a disinfectant with a spritz of chardonnay. It worked. He found that dry white wines, such as Sauvignon blancs or chardonnays, work best because they don’t stain or leave a sticky residue. Never one to waste anything, Daeschel has created a new market for vast supplies of waste and surplus wine. This is the stuff that doesn’t meet vintners’ standards for quality and flavor and would never make it to the bottling stage. Environmental regulations no longer allow waste wine to be dumped down the drain. So vintners have been interested in this potential new market, turning sour grapes into a hot commodity.

Man spraying a water bottle. Raisins.

OSU food scientist Mark Daeschel explores the unexpected properties of everyday products—including wine, raisins, crab shells and water—to discover new ways to fight food-borne disease. Photo: Lynn Ketchum

 

Raisins replace chemical preservatives in beef jerky. Photo: Lynn Ketchum

Creating new uses for seemingly useless stuff is Daeschel’s genius. His motto is “Keep it simple.” And it doesn’t get much simpler than water. As if with a magic touch, Daeschel found that when he split water molecules in the presence of salt he created a powerful antimicrobial agent. When he sprayed this electrolyzed water on fresh vegetables, he saw that it quelled bacterial spoilage. He found it was especially effective on alfalfa sprouts, those moist little threads that can create a perfect storm of bacterial infestation in restaurant salad bars. Since then, Daeschel has experimented with new applications for electrolyzed water, including as a way to clean pipes in beer distilleries.

“People have the notion that here in the United States, where we can put a rover on Mars, we should never have food-borne illnesses,” Daeschel says. Unfortunately, that’s not the case. Almost 76 million illnesses and 5,000 deaths are due to food-borne disease each year. As a result, the fear of litigation is motivating change in the food industry. Daeschel has served as an expert witness on several high-profile court cases, including those involving Odwalla juice and Jack-in-the-Box burgers. He has a unique view of the growing impact of litigation on current food safety needs. Increased litigation in the food industry has meant that everything in food production must be documented, and this has drastically increased costs. It has also focused industry attention on ways to ensure food safety without chemical additives.

“The hunt is on for natural solutions,” says Daeschel. And he adds that non-chemical alternatives make good economic sense. A new chemical food additive can take five to ten years to develop and could cost between $3 and $10 million in research, development and testing. Daeschel and his colleagues at Oregon’s Agricultural Experiment Station are finding that many foods can be used as ingredients as long as their active antimicrobial component remains in its natural condition. They found that anything with strong sensory response is a likely candidate to have antimicrobial properties—spices, garlic, orange peels, even sauerkraut. And by using one kind of food to preserve another kind of food, Daeschel circumvents the costly process of chemical development and testing. The cost of developing a food-based preservative, for example, can be one-tenth the cost of chemical additive development. And developing alternative uses for existing food products adds value with no extra cost.

Food industries, eager to expand markets for their products, have taken note. When the raisin industry was facing economic peril, they contacted Daeschel in hopes that he could find a new use for raisins that would add value to their sagging market. Daeschel thought that perhaps the concentrated sweet of raisins could replace the need to use the preservative sodium nitrite. “Who’s ever seen raisin bread go moldy, even when it’s left out for several days?” Daeschel quips. So he tested raisins to find out what they could do.

Bean sprouts. Water dripping from faucet into a bucket.

Electrolyzed water, produced by splitting water molecules in the presence of salt (right), can be a powerful antimicrobial, useful for cleaning pipes in beer distilleries or quelling spoilage in fresh vegetables such as bean sprouts (left). Photos: Lynn Ketchum

He found that raisins have a unique combination of high sugar and high acid. The acid in raisins, like the acid in wine, is a bona fide killer, just as effective at inhibiting bacterial growth as sodium nitrite. So, Daeschel created a beef jerky using raisins to replace the chemical preservative. Consumers liked the sweet-and-sour flavor. And they liked the fact that it’s healthier than the chemically preserved product, with less fat and more fiber and antioxidants.

Daeschel has the California raisins singing his praises. His phone now rings off the hook with calls from meat companies, even veggie-burger companies, interested in the potential properties of raisins.

Demand continues to grow as consumers choose food with only natural ingredients and food companies seek alternative markets for their products. Daeschel continues his quest for a natural recipe to avoid disaster.

It's a Wrap

By: Peg Herring

What do you get when you cross an egg white with a crabshell?

You get a thin film, sort of like Saran Wrap, that prevents food from spoiling and can be eaten along with the food that it wraps. It can even be fortified with vitamins and minerals so the food and the film together make a more nutritious fare.

This super packaging is the latest technology to come out of Oregon State University’s Department of Food Science and Technology. The film combines two key ingredients: a fiber from shellfish (chitosan) and a protein from egg whites (lysozyme). And its discovery combines the ingenuity of two OSU researchers: Yanyun Zhao, a food technologist and specialist in value-added products, and Mark Daeschel, a microbiologist and specialist in food safety.

Woman dipping strawberry in glass jar.

Su-il Park peers through the super food wrap he helped develop at OSU’s Food Science and Technology Department. Photo: Lynn Ketchum

For several years, Zhao has been experimenting with chitosan to develop thin protective coatings for perishable fruits and berries. Chitosan is a key ingredient in crabshells and shrimp shells, the tough exoskeleton that serves as protective armor. She found that the tasteless natural fiber inhibits the growth of microbes that cause rot in fresh berries and other foods.

At the same time, Daeschel has been experimenting with lysozyme as a natural preservative in beer and wine. Daeschel found that the egg white protein was just as effective as chemical sulfites in preventing unwanted microbial growth, without compromising the taste or quality of the product.

The scientists realized that their two key ingredients each have particular antimicrobial properties that could enhance each other if combined.

Working with postdoctoral research associate Su-il Park, Zhao and Daeschel began experimenting with ways to combine lysozyme and chitosan to create an anti-microbial food wrap. The product they have developed and recently patented looks like familiar sandwich wrap, but delivers much more.

Because it is made entirely from food products, the wrap is edible. It’s so thin that it doesn’t interfere with the texture of the food it covers. And it is made from powerful natural antimicrobials, so it keeps fresh food from spoiling.

The technology behind the new food wrap has many potential applications.

“You can use it as a film to wrap foods or you can use it as a spray or dip to coat foods,” Zhao explained. “And you can enrich the film or coating with extra nutrients, such as vitamin E and calcium, to boost the nutritional value of the food.”

Woman dipping strawberry in glass jar.

Yanyun Zhao, OSU food technologist, coats fresh strawberries with thin, antimicrobial film. Photo: Lynn Ketchum

“These are naturally occurring ingredients,” said Daeschel. “The chitosan is derived from seafood shells, much of which is otherwise wasted. This is a good example of adding value to an existing product.”

Adding value to food products is what Zhao does. As a researcher with Oregon’s Agricultural Experiment Station and value-added product specialist for OSU Extension, Zhao finds ways to increase the economic value and consumer appeal of agricultural commodities.

When a recent survey of the Oregon fruit industry revealed their need for added value to their products as a result of global competition and new market demands, Zhao responded. She took on the challenge to extend the shelf-life of Oregon’s fresh berries.

Zhao developed a thin liquid using chitosan and other natural ingredients and dipped fresh raspberries and strawberries, fondue-style, to test how long they would stay fresh. She found that the dipped berries stayed fresh and juicy for two to three weeks in the refrigerator. Chitosan already had a reputation for various health benefits, including cholesterol reduction. Zhao demonstrated its antimicrobial benefits as well.

This led to the collaboration with Daeschel and his work with lysozyme.

The next challenge for Zhao, Daeschel and Park will be to develop practical applications for their super food wrap. The possibilities extend to packaging for ready-to-eat meats such as hot dogs, sausage and luncheon meat; packing films for cheese slices, blocks and sticks; and coatings for sliced fruits and vegetables that are highly perishable.