Putting on the Pressure: ‘No Heat’ Way to Zap Pathogens

“The most promising food-safety innovation in recent years.”

In the world of food safety, it’s not just about food poisoning outbreaks and recalls. Sometimes there’s some good news to share. That’s the case in breakthroughs and advances in science and technology that can stop foodborne pathogens dead in their tracks. And sometimes that sort of news appears in unexpected places.

Take, for example, the January edition of Popular Mechanics. In a section about the “Ten Tech Concepts You Need to Know,” readers learn that “this year’s big ideas in tech will make your food safer, make hybrid cars more energy efficient, and sentence overpriced texting plans to death.”

Right out of the gate, at the top of the list, is a USDA-approved food-safety process that the magazine refers to as “Pascalization,” commonly known in the food industry as HPP, or high pressure processing. And while it’s only been used on the commercial level for the past 2 decades or so, the technology has been around far longer than that.

Turns out that none other than French scientist, mathematician and philosopher Blaise Pascal (1623-1662) conducted research on food preservation. What he came up with — high pressure processing — is what Popular Mechanics describes as “changing the way we think about food.”

This process doesn’t rely on heat, such as pasteurization; or chemicals, such as preservatives; or irradiation to kill the harmful bacteria on food. And while heat and cooking are good ways to kill bacteria, they can also impair the flavor, texture, color and nutrition of the food. For the most part, the same is true of irradiation.

Under high pressure processing, already packaged products such as fresh hamburger and turkey; processed fruit such as apple sauce; oysters; fish; guacamole; and ready-to-eat meats such as sliced turkey, pastrami and beef are put inside a pressure chamber. Water is then added to the chamber before it is sealed. From there, the pressure is increased to the maximum desirable level and sustained for a set period of time. The chamber is then decompressed and drained and the packaged products are removed.

We’re talking about a lot of pressure. For example, at sea level, air pressure is 14.4 pounds per square inch. In the case of products put under HPP, the pressure ranges from 60,000 to 87,000 pounds per square inch.

And while that sounds like enough pressure to squash or damage the packaged food, that doesn’t happen because the pressure is applied equally on all areas of the product.

The good news is that the pressure zaps foodborne pathogens such as E. coli O157:H7, Listeria and Salmonella, as well as “spoilage” microorganisms such as molds and yeasts — without affecting the nutritional qualities or the taste of the food products. That’s because while it has enough force to significantly disrupt cellular activity, it doesn’t affect the structures of the food components that are responsible for nutrition and flavor.

Another plus is that because HPP is applied when the products are already packaged, it eliminates the possibility of cross-contamination. In other words, the products are free of pathogens when they get to the customers, whether they be grocery shoppers, restaurants, schools or other institutions. Even so, people preparing the food must follow basic food-safety procedures, such as washing their hands and preventing cross-contamination with other foods or cooking utensils to keep the food safe from foodborne pathogens.

But HPP isn’t a one-step-and-it’s-safe sort of approach to food safety. Companies that use it also follow standard food safety principles all the way down the line.

Last year when Food Safety News wrote about HPP, the big news was that meat-processing giant Cargill had introduced a patent-pending process for a new line of fresh hamburger patties produced under high pressure processing. At the time, the company hailed it as a “natural option for food safety” and a “technological breakthrough.” Until then, no one had figured out how to use high pressure processing on fresh hamburger meat without affecting its taste, texture or appearance.

The patties were slated for the food service industry, with customers such as restaurants saying that they were looking for a “fresh hamburger” option with good shelf life. According to a news release from Cargill, the HPP burgers have double the shelf life of non-HPP burgers. Yet the fresh flavor stays intact and food safety is enhanced.