New Pasteurization Processes Give Food Companies Options

Thermal pasteurization systems continue to improve, giving food and beverage processors an expanding universe of alternative treatments that align with changing market demands.

By Kevin T. Higgins, Managing Editor

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RFmachineAn unintended consequence of the Food Safety Modernization Act is a small explosion in the number of new pasteurization technologies available to food processors.

As processors undertake their due diligence in evaluating potential safety hazards in their production processes, many are finding that ingredients and raw materials previously considered no-risk actually are potential carriers of microbial or viral hazards. FSMA requires processors to take steps to remove those risks, and that can mean adding a pasteurization step.

In addition, some industrial manufacturers are demanding that their ingredient and raw-material suppliers pasteurize their finished goods prior to shipment. The aforementioned risk assessments have inspired a proactive approach to even low-moisture products that carry a slight probability of microbial contamination. Those ingredients and raw materials usually are subject to a kill step in the manufacturing process, but once inside the four walls of the plant, food pathogens can migrate undetected to any area, including packaging.

“Been there, done that,” is the knowing reaction from growers of almonds, a low-moisture food that was considered exempt from salmonella contamination until outbreaks in 2001 and 2004 proved otherwise. At the growers’ request, USDA in 2007 began requiring that all almonds, whether raw, blanched or roasted, be treated to achieve a 4 log reduction in salmonella. Consequently, equipment manufacturers and technology providers validated their systems and submitted them for review to the Almond Board of California’s Technical Expert Review Panel (TERP). The result is hundreds of validated pasteurization systems, including many alternative and leading-edge technologies.

Even when thermal or chemical treatment is the defense against pathogens, operating systems are subject to continuous improvement. When Deamco Corp. engineered a pasteurization system for Hilltop Ranch in Ballico, Calif., space constraints necessitated the use of a vertical pasteurization chamber and two Kason vibratory fluid bed cooling and drying units, which were selected because of their small footprints. The design resulted in a system half the size of a comparable pasteurizer. Real estate always is in short supply, though higher throughput, not space savings, remains the primary driver in pasteurization system design, notes Deamco’s Armand Guilion.

Throughput may be manufacturers’ priority, but consumers want minimal processing and nutrient retention, particularly with products associated with healthy eating. Nuts, seeds and sprouted grains are among the fastest growing food categories, and a number of TERP-approved processes retain the flavor, mouthfeel and nutrition of raw seeds and grains.

Among them is Log5, a system developed by Duyvis Wiener, a Dutch firm that originally engineered the system to treat cocoa and chocolate. The system mixes humid air with saturated (dry) steam to manipulate water activity and temperature level with moist heat and achieve a 5 log bacterial reduction without adversely impacting product quality. The first North American unit is expected to be commissioned in August at CHS Inc.’s sunflower seed facility in Fargo, N.D.

The continuous process can pasteurize up to 20,000 lbs. an hour, depending on the product, according to Jochem Dekker, vice president at Log5 Corp., ( Phoenix, Md. Because temperatures are above the dew point, moisture pick-up doesn’t occur, and the machine can both pasteurize and roast, says Dekker. The firm has U.S. orders for three more machines.

Saturated steam and vacuum are employed by Napasol North America LLC ( to pasteurize at a relatively low temperature. The batch process was installed last year at Hazelnut Growers of Oregon’s facility, pasteurizing 15,000 lbs. per hour. Systems capable of processing volumes as high as 30,000 lbs. per hour can be fabricated, according to David Barbera, business development director of the Fargo, N.D., unit of the Swiss firm.

Nuts, seeds and dried fruit can be pasteurized in either static or rotating autoclaves. Product is placed in bins before entering an autoclave, then transferred to a cooling plenum. The batch approach reduces the possibility of cross contamination, Barbera points out.

Electricity generates most of the thermal wallop in Revtech Process Systems’ sterilization and pasteurization technology, with a blast of saturated steam finishing off any surviving microbes. A bigger distinction is the vibratory transport of the product with a technique described as impedance tube transfer by managing director Martin Mitzkat, cofounder of the Loriol-sur-Drome, France-based firm (

Direct contact with a hot tube is the primary kill mechanism, and manipulation of counterweights to motors at either end of the circular tube creates the vibration. The earliest systems had two-inch diameter tubes; scale up to higher-throughput machines has produced 10-inch versions that can process 10,000 lbs. an hour. The next engineering challenge: a machine capable of 33,000 lbs. of throughput.

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