Farm Progress

Method destroys bacteria in food while retaining health-promoting nutrients.

January 20, 2017

4 Min Read
LONG SHELF LIFE: Packaged guacamole is just one type of food available today that's undergone high-pressure processing for fresh flavor, preservation and safety.wmaster890/iStock/Thinkstock

Consumers increasingly want fresh, natural foods with no artificial preservatives, minimal processing, and wholesome, recognizable ingredients. Such foods offer a “clean label,” which Food Business News identified in 2015 as “Trend of the Year” and in late 2016 estimated as a $62 billion market in the U.S.

A novel technology, known as high-pressure processing, can help provide just that. And it’s gaining attention throughout the food industry, says V.M. “Bala” Balasubramaniam, professor of food engineering with Ohio State University’s College of Food, Agricultural and Environmental Sciences. His laboratory, with a multidisciplinary team of microbiologists, chemists and nutritionists, investigates innovative food processing technologies to allow industry to implement them.

Balasubramaniam is the primary author of “Kinder, Gentler Food Processing,” the cover story in December’s issue of Food Technology, the magazine from the Institute of Food Technologists. Known internationally for his pioneering research on high-pressure and other types of nonthermal processing, or safely processing food without heat, Balasubramaniam holds joint appointments in the departments of Food Science and Technology, and Food, Agricultural and Biological Engineering.


V.M. “Bala” Balasubramaniam

“Consumers are interested in additive-free, chemical-free foods, and high pressure offers the ability to reduce additives while retaining health-promoting nutrients,” Balasubramaniam says. “But we are finding it does other things, too.”

The amount of pressure used is significant: 87,000 pounds per square inch, give or take, compared with normal air pressure at sea level of about 14.4 psi. The packaged food experiences the equivalent of the water pressure at about 35 miles below sea level. Though the food is exposed to very high pressure, it is applied uniformly across the entire surface, so contrary to popular expectations, Balasubramaniam says the food’s structure is preserved after the process.

Process destroys bacteria
While the pressure is high enough to destroy bacteria, such as salmonella and E. coli, it allows the prepackaged foods to retain important nutrients and other fresh-like qualities that can be destroyed by the heat used in traditional canning and pasteurization, he says.

Lisa Pitzer, marketing director with Avure, a Cincinnati area-based manufacturer of high-pressure processing equipment, says: “Guacamole that you make fresh would last maybe two or three days. But after guacamole has been high-pressure processed, it lasts 40 days, and it tastes just as good as the day you made it. And you don’t have to worry about getting sick.”

Consumers are already purchasing high-pressure processed foods perhaps without even realizing it, Balasubramaniam says. The products can be found in delis and the refrigerated section, and include sauces, fruit juices, smoothies, nut milks, lunch meats, seafood, salsa, vegetable products, deli salads and guacamole.

Beverages are often labeled as “cold-pressed,” Pitzer says, although terms such as “cold-pressured” and “cold-pasteurized” are also used.

“But to be honest, consumers don’t really care about the process,” Pitzer says. What they care about, she says, are foods without additives and preservatives that are safe to consume.

Even so, Balasubramaniam and his colleagues at Ohio State hope to go one better: By combining high-pressure processing with various amounts of heat or electricity, they can destroy harder-to-kill pathogens, such as the spores that cause botulism.

“For really harmful spores like Clostridium botulinum, you need much more hammer power — highly intensive pressure and increased temperature to kill them,” he says. Balasubramaniam’s work is identifying the right combinations of pressure and temperature to allow fresh foods to remain shelf-stable.

And he’s also making other discoveries by developing high pressure-based clean-label technologies for food and beverage products.

For example, in work with beverage processors, Balasubramaniam found that a dairy-based product processed with a continuous high-pressure process tasted much sweeter than the traditionally processed product.

“What that means is that we can reduce some of the sugar in the product and still have the same sweet taste,” he says. 

Other products react similarly, enabling manufacturers to reduce fat and salt in their products, as well, he says. Yogurt that is processed with high pressure becomes much creamier than traditionally pasteurized yogurt.

It’s not clear how high-pressure processing causes these effects, he says.

“When you work with a new technology, you first make observations; then it takes a while to fully understand why things are happening,” Balasubramaniam says. His Food Safety Engineering Laboratory is continuing its research in collaboration with food processors and equipment vendors to develop continuous high-pressure processes for various beverage products.

Pitzer says the high-pressure processing industry is forming a consortium that will focus on consumer education about the process and will develop a label so consumers can identify high-pressure products that adhere to industry standards.

“High-pressure processing offers a lot of opportunities to extend the shelf life of minimally processed foods,” Balasubramaniam says. “It’s leading the way to allow many types of food to carry a clean label, which is what consumers want.”

Source: OSU Extension


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