Many food manufacturers covet a cold pasteurization technique called high pressure processing (HPP) because it helps a product to maintain its original freshness throughout its shelf-life.
The FDA recognizes HPP for preserving freshness and increasing shelf life without preservatives or high heat. The process leads to the elimination of harmful bacteria while maintaining a higher yield of vitamins, minerals and enzymes, and preserving a fresher taste, according to www.coldpressured.org.
HPP can be used on a variety of fresh food products including juices, dips, salsas, dairy, meat products, seafood products and even cosmetics.
WHAT IS HIGH PRESSURE PROCESSING?
High pressure processing consists of loading a product sealed in a flexible container into a high pressure chamber filled with a pressure-transmitting (hydraulic) fluid. The hydraulic fluid (usually water) in the chamber is pressurized with a pump, and this pressure is transmitted through the package into the food itself. Pressure is applied for a specific time, usually 3 to 5 minutes, up to 87,000 psi. The processed product is then removed and stored/distributed in the conventional manner. Because the pressure is transmitted uniformly (in all directions simultaneously), food retains its shape, even at extreme pressures. And because no heat is needed, the sensory characteristics of the food are retained without compromising microbial safety
According to hyperbaric.com, “pressures above 400 MPa / 58,000 psi at cold (+ 4ºC to 10ºC) or ambient temperature inactivate the vegetative flora (bacteria, virus, yeasts, moulds and parasites) present in food, extending the products shelf life importantly and guaranteeing food safety.”
HYDRAULIC PUMPS: THE SECRET INGREDIENT OF HPP
Hydraulic pumps create the necessary pressure required to carry out operations like HPP, says BCC Research analyst Aneesh Kumar. In the food packaging industry, the “ease of operation and low operational costs along with factors such as capacity, pressure, drive speed, fluid characteristics, and efficiency have fueled the demand for hydraulic pumps,” Kumar notes.
“Hydraulic pumps are used to minimize energy wastage or fluid leakage and to increase the performance and efficiency of machinery or equipment, all of which can significantly affect the overall costs of a plant or equipment,” he says. “They’ve become the preferred option for operations involving mobile hydraulic equipment and industrial machinery, as well. Even though hydraulic pumps face competition from alternative technologies such as electrical pumps, water pumps, and pneumatic pumps, they continue to be the most preferred choice in high-pressure applications such as mining, oil and gas exploration, and other industrial applications mainly because of their ability to save energy and provide higher efficiency,” he adds.
During HPP, pressure is uniformly applied around and throughout the food product. As described by coldpressured.org site, a grape placed between fingers can be easily squeezed and broken because the pressure is unevenly applied from all sides simultaneously. But, if the same grape is squeezed from all sides simultaneously, it will not be crushed. To demonstrate this property, place a grape inside a soda bottle filled with water. As you squeeze the bottle, you pressurize the water inside as well as the grape. Yet the grape remains unharmed, no matter how hard you squeeze. It’s the same way with foods processed by high pressure are undamaged by the applied pressure.
A COMPANY ADOPTS HPP: A QUICK INSIDE VIEW
Texas Food Solutions (TFS), a Texas-based startup company, recently designed and engineered its HPP processing line for its sister company’s line of refrigerated ready meals. The fully cooked 8- or 9-oz. meals feature a protein such as chicken or pork, a rice or pasta, and a green vegetable.
As TFS President Jasmine Sutherland relates to Pat Reynolds, in typical HPP installations, high-pressure tubing represents one of the most expensive components. Sutherland says, “Putting the hydraulic pumps directly over the HPP system itself rather than in a separate space or room nearby is the most direct and efficient route that requires the least amount of high-pressure tubing.”
As described by Reynolds, the automated process starts after food packages are loaded by hand into three injection-molded high density polyethylene baskets, which are then pushed into a stainless steel vessel, which, after being closed off by steel plugs at either end, is pushed into a high-pressure chamber and blocked off by steel spacers. Water then floods the chamber, at which time three overhead hydraulic pumps create 87,000-psi pressure inside the chamber.
“The pressure generated is the equivalent of three 747 airplanes stacked on top of each other and all sitting on your iPhone,” Reynolds quotes Sutherland.
The baskets remain under pressure inside the chamber for about three minutes. Then, the process is reversed to the point where the plugs are opened at each end so the water can drain out. Three new baskets are pushed in (beginning a new cycle), displacing the processed baskets for unloading. Each cycle lasts about eight minutes, according to Reynolds.
As Sutherland tells Reynolds, “We went pretty quickly from thinking about buying one HPP system and putting it in our food processing facility to building a new facility for our first HPP system and planning for the installation of a second HPP system. The market for this kind of refrigerated shelf life extension technology is growing, and we felt we could be very good at it.”
BCC Research projects that the global market for hydraulic pumps will grow from $7.5 billion in 2013 to $7.9 billion in 2014 at a one-year CAGR of 4.8%. In addition, the market is expected to grow at five-year CAGR of 4.9% from 2014 to 2019, reaching about $10.1 billion by the end of the forecast period.