Food safety has been the impetus for some of the industry’s most innovative technology in post-packaging pasteurization (PPP). With the goal to eliminate dangerous pathogens, an increasing number of meat processors have incorporated the latest heat and high-pressure methods to increase the level of food safety in their plants.

This quest has been spurred by the USDA’s Food Safety and Inspection Service (FSIS), which has developed regulations and designations for food plants producing ready-to-eat meat and poultry to help ensure the safety of American consumers.

At this time, a number of companies have made it their mission to develop more effective and less costly PPP systems that can be more easily incorporated into meat processing plants.

The science and technology of high-pressure PPP has come a long way since Europe and Japan began researching the effects of hydrostatic pressure on microorganisms in the 1990s. During this period, the U.S. Department of Defense became active in funding research for high-pressure pasteurization to help improve combat rations.

About a decade ago, Ft. Worth, Texas-based Fresherized Foods (formerly Avomex), first began utilizing this method to extend avocado shelf life. According to Marcia Walker, vice president of technology and microbiology, high-pressure technology took off in this country in 2003, when the FSIS came out with regulations for RTE (ready-to-eat) meat operations due to the added food-safety risks of these foods.

The science behind high-pressure PPP follows that microorganisms cannot survive in the deepest part of the ocean, where water pressure measures approximately 60,000 pounds per square inch.

With this pasteurization method, vacuum packaged meats are placed in high-pressure vessels filled with water. The water is then pumped out until pressure builds to between 40,000 and 90,000 pounds per square inch. This pressurization destroys foodborne pathogens.

Kent, Wash.-based Avure Technologies, a supplier of high-pressure processing systems, recently provided seven high-pressure units to a major processor of deli meats for its all-natural line, a type of product that is spurring the use of high-pressure pasteurization.

“The big industry trends driving the use of our systems are consumer demand for products with fewer additives and the huge growth in natural and organic foods,” says Glenn Hewson, Avure’s vice president of marketing. “Food safety is no longer a selling point because it is expected.”

Walker agrees. “This method has become more popular because the FSIS regulatory Listeria rule has challenged companies to categorize their plants as Alternative 1, 2 or 3,” she says. (See “PPP ‘Alternatives’,” right, for more information on these designations.)

One of the biggest benefits of high-pressure pasteurization is that nothing is taken from or added to the meat. Consequently, the flavor is not compromised and nutrients remain intact. This method also is instantaneous and uniform. “The high-pressure process is specific to each package’s dimension,” Walker says.

Because meat is treated after being packaged, it is contained in an essentially sterilized environment. Another advantage is that, with some products, shelf life can be tripled using this method. “Processors can achieve higher revenues because they can offer more innovative value-added products [with longer shelf lives due to high-pressure PPP],” Hewson says.

Yet, a big disadvantage of high-pressure PPP is its cost. For meat processors, this method is twice the price of chemical pasteurization. “While chemical methods cost about 2 cents a pound, high pressure is 4 cents a pound. Because of the added expense, this process is geared toward value-added products, as opposed to raw meat and poultry,” Hewson says.

Because this is a batch process, the throughput can be an issue for big companies. These limitations make high-pressure PPP unsuitable for products produced in massive quantities, such as ground beef. “The challenge is to create high-pressure systems that offer continuous use,” Walker says. ”

American Pasteurization Co. in Milwaukee, Wis., seeks to make high-pressure PPP more attainable to processing plants. Justin Segel, co-owner of the company with George Lang, says a company processing one million pounds of meat a year is an ideal candidate for this process, but the equipment’s large size and expense make it prohibitive. “Our company provides high-pressure pasteurization as a tolling service,” Segel explains. “Companies send us their product, we apply high pressure, provide assembly for kits and sleeve packaging if necessary, and arrange the logistics, including transportation, to the distribution center.”

American Pasteurization serves companies making as little as 30,000 pounds of product annually. “We charge on a per pound basis, spreading the cost to help companies avoid the capital expenditures for high-pressure PPP,” Segel says.

The company essentially functions as a piece of the supply chain. “We have a HACCP plan, which integrates with our customers’ plans, and we are regularly inspected by the USDA,” Segel says.

In the coming years, the company plans to build a network of high-pressure plants across the country to help accommodate its growing customer base. “Our volume is starting to take off. We are gearing our plant to process about one million pounds of product a week,” Segel says.

Along with high pressure, heat is another effective method for eliminating pathogens in the post-packaging arena. Hot water PPP systems maintain a constant temperature of 205 F by means of steam injection. Product is submerged in a tank for 60 to 180 seconds to raise surface temperatures to between 170 F and 180 F.

Craig Bernheimer, sales representative for Unitherm Food Systems, based in Bristow, Okla., says that although this process raises the meat’s surface temperature, it does not affect the internal temperature. “This process does not cook the product. It kills the pathogens inside the package,” he says.

Another heat PPP method is flash pasteurization. In flash pasteurization, product that is packaged but not yet vacuum-packed is loaded into a flash chamber and heated with ambient steam at temperatures exceeding 200 F for a couple of seconds.

Heat PPP methods are mainly used for hot dogs, deli products, molded turkey breast and large whole-muscle meats.

In the past, there were a number of challenges with these heating methods. One was the cost of switching packaging films to types that could withstand the high temperatures of the process. The other problem for processors was the large space needed to accommodate these units.

Seth Pulsfus, manager of technical service and R&D at Alkar-Rapid Pak in Lodi, Wis., says technology is improving, and the industry is getting close to commercializing flash pasteurization. At press time, the company was launching a new system that could be directly incorporated into a plant’s packaging line. With today’s technology, Pulsfus says only 4 feet of space is needed for newer flash-pasteurization units. “Our new system also can use existing packaging films, [making it less costly to incorporate],” he says.

Like high-pressure PPP, this method destroys pathogenic and spoilage bacteria, substantially increasing product shelf life. Also, this PPP process can be used by plants seeking an Alternative 1 designation.

Among the newer innovations is a stronger and more adaptable packaging that can be used with heat PPP systems. Carroll Manufacturing & Sales (CMS), of Avon, Ohio, offers a bag that can withstand a temperature of 210 F for up to 10 minutes. Ryan Till, product and sales manager, says this line, geared for use with RTE deli products, has a strong seal that can endure the rigors of this process. “The bags have the same function and properties of traditional shrink bags but are constructed of a different resin for added durability,” he says.

Experts agree that the popularity of PPP processes is on the rise. “Everyone is trying to do some form of it,” says Till. “It is great for food safety, and retailers recognize this. Also, plants that do PPP are held to a higher standard by the USDA.”

Lisa White is a freelance writer based in the Chicagoland area.

All establishments producing RTE products, which are exposed to the environment after lethality treatments, are required by the USDA’s Food Safety and Inspection Service to develop written programs such as Hazard Analysis and Critical Control Point (HACCP) systems, Sanitation Standard Operating Procedures (SSOPs), or other prerequisite programs, to control Listeria.

There are three alternatives to complying with this rule.

- Alternative 3 plants have the fewest food-safety controls in place, relying mainly on basic sanitation methods to control pathogen growth. These establishments are subjected to increased product testing and sampling to ensure the food is safe.

- Alternative 2 plants incorporate a more extensive sanitation program that tests food contact surfaces in a post-lethality processing environment. These establishments must indicate the frequency of testing, identify the size and location of the sites to be sampled, include an explanation of why the testing frequency is sufficient to ensure the effective control of harmful pathogens, and institute a hold-and-test procedure for food that tests positive for Listeria. These plants are tested less often by the USDA than Alternative 3 operations.

- Alternative 1 plants take the highest precautions to reduce the likelihood of contamination, and therefore are subject to the least amount of product testing and sampling by the USDA. An establishment that is deemed Alternative 1 utilizes both a post-lethality treatment, such as post-packaging pasteurization, along with an anti-microbial agent or process to control Listeria growth.