Thriving under pressure

Product recalls on the account of food contamination are arguably every food processor’s worst nightmare these days-despite all the vast technological and engineering advances made over the years to improve the safety, shelf-life, freshness, flavor and nutritional value of many of today’s popular packaged food products.

And while the ultimate ‘silver bullet’ solution for completely halting the presence of deadly food-borne pathogens everywhere along the vast food processing supply chain may not yet exist, it may be that a fairly straightforward process, based on a concept first developed back in 1897, will just turn out to be the next best thing-and probably sooner rather than later.

Cost Control

Generally referred to by its HPP acronym, the so-called high-pressure pasteurization process-aka high-pressure processing or high-hydrostatic pressure-has largely been ignored up to now by leading food companies due to the high cost of the equipment and operating expenses, as well as a poor track record of equipment reliability.

However, extensive recent work by researchers at the Wolfertschwenden, Germany-headquartered packaging machinery manufacturer Multivac Sepp Haggenmüller GmbH & Co. KG is reported to have resulted in the development of a cost-effective concept for integrating equipment for HPP treatment of a broad range of prepackaged food products into fully-automatic, high-speed packaging lines, fully accommodating any existing vacuum-packing or MAP (modified atmosphere packaging) systems already running on those lines.

Under the high-pressure treatment refined by Multivac, packaged food is subjected to period of a high pressure up to 6,000-Bar (87,000-psi) in a so-called autoclave-a lockable, gas-tight pressure container-to kill off any potentially deadly microorganisms such as listeria or salmonella within the packaging.

Because the process is conducted under ambient temperature, even heat-sensitive food products can be treated by HPP to extend the product shelf-life by up to four time longer than via conventional MAP methods, while still maintaining the product’s original taste and nutritional value, according to Multivac, which says the new technological breakthrough can enable many packaged foods producers to comply with the increasingly stringent food safety regulations around the globe.

Until now, most HPP treatments have been carried out in a separate manufacturing stage that involved the manual loading of packaged product into the high pressure container, which was neither efficient or cost-effective for most food plants.

However, a few technical innovations enabled Multivac to develop a pioneering solution that essentially integrates HPP equipment to treat the packaged foods directly on  the production line, according to the company.

The fully-automated solution (see image above) comprises a high-pressure unit with one or more autoclaves-developed by ThyssenKrupp‘s sister company Uhde High Pressure Technologies-integrating the HPP process into packaging lines laid out to meet food industry safety requirements.

Loading Up

In operation, the finished food packs are automatically loaded into transport containers and immediately subjected to HPP treatment in the autoclave, after which they are automatically unloaded, dried, printed or labeled, if required, and finally packed into shipping cartons.

“This HPP process offers, for the first time, a way to process large, industrial-scale production quantities fully automatically in a quasi-continuous operation,” says Tobias Richter, product manager at Multivac’s Systems Business Group unit.

According to Richter, Multivac has even developed an HPP process that is totally compatible for use with MAP packs, and the company has the capabilities to custom-design similar HPP systems to meet specific customer needs.

“In order to achieve as high a machine throughput as possible, the available space in the autoclave must be used as intelligently as possible,” explains Richter.

“Because the HPP equipment is round in shape, for reasons of optimizing the distribution of pressure forces, the loading pattern also has to be designed accordingly.”

Right Choice

Likewise, Multivac can also help customers in choosing the optimum package shape and selecting the proper packaging materials to produce a package that makes optimal and most efficient use of the HPP treatment, says Richter, adding that depending on the design and suitability of a given package shape, Multivac’s HPP solution can process from two to four tonnes of packaged food per hour.

“With our extensive know-how and comprehensive range of services, Multivac can fully support its customers in choosing the optimum package shape, in selecting the materials that make up the package, and in the actual carrying out of the high-pressure process.

“To help facilitate that, a testing area was built at our Uhde High Pressure Technologies complex, which also doubles as a place to provide a wide range of advisory services to our clients.”

Richter says that Multivac researchers paid key attention to the importance of maintaining package integrity-especially with MAP packs-throughout the HPP process when designing the system, which is why they optimized the HPP unit in a way that relieves high pressures in the autoclave in a controlled manner.

“With the help of so-called ‘holding torque,’ we can create short rest periods in which the polymer can regenerate,” Richter states. “In this way, the packaging material is stressed considerably less than it would be otherwise, enabling it to retains its functionality even after intense high-pressure treatment.”