The process was invented by French chemist Louis Pasteur in 1862 and is used today to reduce the number of potentially harmful pathogens in food.
Though pasteurization has prevented countless illnesses and deaths, critics claim the process often alters the product's taste and nutritional value.
An emerging technology, however, could revolutionize food processing, making some foods safer and, potentially, greatly extending their shelf-life.
Jeannie Campbell explains how some companies are "putting the squeeze" on food pathogens with high-pressure processing.
Rep. Greg Walden, R – Oregon: "For the sake of consumers, what can be done for food safety…"
Even as concerns over food safety have grown, so has the demand for more natural, less processed foods. USDA numbers show that for over a decade there has been double-digit growth in consumer demand for organic produce.
Pat Adams, CEO Avure Technologies: "The food industry is all about giving people what they want. In some cases it's high quality, minimally prepared foods that taste as close as possible to something you would prepare naturally. That is the niche market that this technology seems to be most applicable to."
Pat Adams is CEO of Avure Technologies, a company best know for making high-pressure presses that produce industrial diamonds and metal alloys for knee replacements and jet engines. High-pressure technology that can now be used to preserve certain kinds of food.
Pat Adams, CEO Avure Technologies: "The ability to kill bacteria, disease causing bacteria, parasites was recognized over a century ago. Unfortunately the ability to build machinery that could delivery these pressures has only happened in the last decade, decade and a half."
The idea that pressure could be used to kill harmful organisms in milk and other foods was developed by Professor Burt Hite at the West Virginia Agricultural Experiment Station in the late 1800's. While Professor Hite's experiments held some promise, the equipment, even under lab conditions, often failed. It has taken nearly a century for the technology to advance where pressures of over 80 thousand pounds per square inch can be safely achieved in a production line.
Errol Raghubeer, Avure Technologies: "As a researcher almost every day that we use this technology we find out something new, something different, something exciting, not exciting just in killing microorganisms any more, we can really make foods taste better, feel better…."
Errol Raghubeer is a researcher at Avure Technologies. Avure only makes the machines that are capable of high pressure processing and is not in the business of processing food. The company does however run a test kitchen and has found that some foods do better under pressure than others.
Errol Raghubeer, Avure Technologies: "An example of a product that doesn't work is a marshmallow. This is after high pressure and this is before. We just squeezed all the air out of it, there is no resiliency within this to bring it back to its shape and the original form."
86,000 pounds of pressure per square inch, which is roughly equal to three, 5-ton elephants balanced on a dime, flattens a marshmallow but has no effect on a grape.
Errol Raghubeer, Avure Technologies: "You see it's almost 100% water. And, if you compare it with a grape that has not been processed, really there is no difference."
What keeps the grape from being crushed is the fact that it is mostly water and that the pressure is applied evenly from all directions.
Errol Raghubeer, Avure Technologies: "Some of the products you have on the market, if you take a look at the label they are very, very high levels of preservatives inside in order to give them that shelf life. Here we are using natural methods of high pressure processing in order to get that shelf life, tremendously longer also than what you would get with just adding preservatives and salt."
In Bay Center, Washington the Goose Point Oyster Company is using high pressure processing, or HPP, to take the risk out of eating raw oysters. The process, which is similar to any food that is processed using high pressure, involves loading oysters into a canister, filling the canister with water, then pressurizing the contents. The water applies pressure evenly to whatever else is in the canister.
43,000 pounds of pressure for 90 seconds kills any potentially deadly pathogens. Jeri Joy is the director of marketing at Goose Point Oysters.
Jeri Joy, Goose Point Oysters: "For oysters it gives us an extended shelf life of seventeen days fresh in the shell. We don't see that on, you know, live oysters in the shell. And I think if you put the two side by side you would really, really have to be a connoisseur to tell the difference between a fresh, live oyster and an oyster that's gone through the high pressure process."
Juices, sauces and sandwich meats are some of the other products currently using high pressure processing. In Milwaukee, Wisconsin, the American Pasteurization Company does not produce a product but instead offers high pressure processing as a service to packers and producers. Justin Segel is co-owner of APC.
Justin Segel, American Pasteurization Company: "As great as the technology is for shelf life and food safety etc, you still have to make enough money to stay in business and we think we offer an economic benefit of allowing our customers to utilize equipment and this technology without the enormous cost of having to do it themselves."
According to Segel, high pressure processing is more expensive but has advantages over traditional processing that can give it an economic advantage. High pressure processing means there is no need to use heat or add chemical preservatives. Food can be processed after it is already packaged. And, the process actually extends shelf life which means grocers see less spoilage.
Justin Segel, American Pasteurization Company: "I think we're raising the bar. I think that technology raises the bar."
At Oregon State University, researchers experimenting on milk, have found that using high pressure processing in combination with heat could yield even more benefits than just using pressure.
Antonio Torres, Oregon State University: "We didn't expect it to happen, but what we discovered was that when you use pressure combined with heat, pressure actually inhibits the damage that heat normally does If I heat milk, by itself, I damage it, but if I combine pressure of heat, the heat damage is removed by pressure. That's a very unique situation."
Currently, heat pasteurization gives milk a shelf life of 15-20 days. In the experiments at Oregon State, adding pressure and using temperatures lower than are presently used to pasteurize milk, the shelf life exceeded 45 days. According to Torres, using high pressure processing and higher temperatures could lead to milk that would not require refrigeration and have a taste that consumers would find acceptable.
It would seem that a product with no preservatives and longer shelf life would be highly promoted but finding high pressure processed products that are already in grocery stores isn't easy. Justin Segel believes that as awareness in the process grows, consumers not only will look for HPP products but will ask for them.
Justin Segel, American Pasteurization Company: "I don't want to use the term a silver bullet, but there's a technology out there that is not irradiating things, it's not better living through chemistry, it's, it's just a the physics of putting something under pressure and decompressing it."
For Market to Market, I'm Jeannie Campbell.