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Processing Innovation is Alive and Well

Aug. 28, 2006
Processing innovation is alive and well. We look at five technologies of tomorrow that are available today (or soon): supersonic processing, high-pressure sterilization, bioseparation, radio frequency heating and carbon dioxide extrusion.

Information technology and automation have dominated food industry capital investment in recent years. At times, processors have sat like wallflowers at a sock hop when innovative concepts asked them to take a spin around the dance floor.


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But make no mistake: Processing technology is alive and well and, in some cases, already knocking on your door with resolutions to timeless industry challenges as:

  • Food safety
  • Huge reductions in process times
  • Qualitative improvements
  • Energy savings
  • Massive productivity gains
  • More healthful products
  • Fewer ingredients and cleaner ingredient labels
  • Dramatic reductions in equipment and process line footprints

As we look ahead to the Oct. 29 co-located Pack Expo and Process Expo, Food Processing surveyed a number of food industry leaders to identify five processing technologies that appear ready to take their place in the food plants of tomorrow.

Supersonic processing

What rolls as many as five processing steps into one, compresses half-hour processes into minutes and cooks with supersonic technology?

It’s a mixing-heating-pumping system called PDX Sonic, developed by Pursuit Dynamics in the United Kingdom and distributed in the U.S. by A&B Process Systems, Stratford, Wis.

The PDX Sonic unit mixes, pumps and heats instantaneously using low-pressure supersonic “shockwave” technology.

A unique technology developed by Pursuit Dynamics and applied to food manufacturing compresses multi-stage processes for sauces, gravies, jelly, soup, condiments, starch thickeners, salad dressings, custard and even complex meat soups into simple, single-station operations. And it is all done within a small footprint.

Initially designed by Australian Alan Burns to propel watercraft, the PDX Sonic system may be the 21st century’s first leapfrog processing technology. Called a “steam-based supersonic shockwave technology,” the PDX Sonic system is, quite literally, a blast, moving steam at supersonic speeds to process in minutes products that may normally take hours.

“PDX replaces several pieces of equipment: a heat exchanger, a pump, a jacketed vessel and a powder mixer,” says Stuart Rigby, Pursuit Dynamics’ head of product and process implementation. “A lot of recipes are multi-stage processes with a preparatory step and four to five processing stages. Multiple stages mean more opportunity for error, but this system limits chances of mistakes by mixing, heating, pumping and homogenizing simultaneously.”

The process equipment is minimal and compact, consisting of hoppers, a mixing vessel and process piping. At the new A& B test center in Stratford, Wis., many products from jellies to ice cream toppings have been tested – with outstanding results.

PDX Sonic also can be used for rapid, precise, quality-controlled cooking of long-grain rice, pasta, scrambled eggs and other foods and for rapid and thorough dispersion of gums, sweeteners and other ingredients. Symbol and soul of the technology is a small (10-in.) and unassuming tube that took four years and roughly $15 million to develop.

As the ingredient mix is added to the hopper, steam enters the annular conditioning chamber wrapped around the PDX. The steam then enters the process flow. The geometry of the chamber drives steam to supersonic speeds, generating a “controllable shockwave.”

When steam moving at such speed hits the fluid, it creates an environment ideal for mixing and heat transfer. The configuration of the PDX, which is available in three bore sizes, drives steam at speeds two and three times that of sound. “When the steam is injected at high speed, it has nowhere to go, so you have 100-percent use of the steam,” explains Rigby.

The company boasts improvements in processing speed of up to 10 times and up to 80 percent decrease in cleaning time due to the eradication of burn-on contamination. According to Rigby, results to date include an Alfredo sauce with zero burn-off, barbecue sauces in 15 minutes instead of 90 minutes and other product successes – most with energy reductions of 50 percent or more. Better flavor and smoother texture are typical. Rigby estimates most companies will experience payback in 10 to 12 months. “It’s wicked for making scrambled eggs as well,” says Rigby.

High-pressure sterilization

High pressure is about to move from a processing technology with pasteurization side-benefits to a viable sterilization technique.

High-pressure processing sidled into the food industry in the early 1990s, catching the fancy of engineers and food scientists but making only slow progress with processors. Used since 1991 in Japan for jellies and jams, high-pressure processing has slowly entered the American processing arena through Avure Technologies Inc., a Gores Group company.

High pressure met its first commercial success in the U.S. market when Fresherized Foods in Keller, Texas, employed it for guacamole dip processing. The technology extended shelf-life fivefold – from 6 days to 30. The process also has been employed for sliced meats in Europe and in a variety of seafood applications.

Fresherized Foods has used high-pressure sterilization for guacamole, including that in its Mexican food kits.

Processing food with minimal heat disruption delivers a fresher, minimally processed food. But its food safety promise has been the greater magnet for interest to date. Virginia Sea Grant, a marine research and advisory group a the University of Virginia at Charlottesville, has sponsored research on high-pressure processing to inactivate hepatitis A virus (HAV) in oysters, opening another door to the technology to enhance the safety of the food supply.

Hormel Foods, Austin, Minn., and Perdue Farms, Salisbury, Md., are employing the process to sterilize lunchmeat, chicken strips, and other meat items and to extend shelf-life to 100 days or longer. Still, with equipment cost on the high end and food safety a constant concern, high-pressure processing has made only limited strides.

Hang on. Better designed, insulated and preheated vessels and better control and monitoring systems have advanced the technology considerably. The process submerges wrapped or packaged product into tanks of pressurized water, killing the food industry’s invisible enemies – salmonella, listeria, e. coli and now even bacterial spores.

“The newest development is a modification of equipment that enables the process to reach higher temperatures,” explains Martin Cole, director of the National Center for Food Safety and Technology, a research consortium among the FDA, Illinois Institute of Technology and the food industry. “This is a big step in preservative technology.”

Cole and colleagues have been testing a 35-liter high-pressure processing system at NCFST’s headquarters, lab and pilot plant in Summit, Ill., where high-pressure studies have been under way for more than five years.

To date, high pressure has been used only in batch processes, but innovations in the technology, including the ongoing development of “tilting vessels,” have helped speed up the process. “The driving force in the development of the technology has been to make it a more fluid process, to move it to an almost continuous process,” says George Allah, senior scientist at Food Products Assn.’s (FPA) Center for Technology.

Though the process has more than doubled the shelf life of meat products, processors have remained cautious, skeptical and divided regarding its efficiency.

Perdue Farms has not extended its date code on products processed with the technology despite highly favorable laboratory results. At least one major processor rejected the process last year for its deli meat operations, complaining that the meat produced was soft and lacking the elastic characteristic of traditionally made deli meats.

More recent developments have yielded more favorable results, however, and Cole and others foresee the industry opening its arms to the process in the not-too-distant future. Some think it will replace the traditional retort canning process.

“A consortium of several food companies has filed an FDA petition to approve the process for food sterilization,” says Cole. “I think we will see it used in the marketplace in the next few years,” says Jeff Barach, vice president and center director of FPA. “The hurdle is consistency and, of course, regulatory matters.”

Bioseparating functional ingredients

Healthful new products. Remarkable functional ingredients. Substantiated label claims to market functional foods to a health-hungry public. All are, as Shakespeare might say, “consummations devoutly to be wished” if you are a food processor.

The functional foods revolution has opened new doors to profit for food processors. But economical extraction of many important functional food ingredients – particularly key phytonutrients credited with health benefits – remains largely unachieved.

Bioseparation of these components is the key. The pharmaceutical industry has the luxury of charging high prices and high profit margins to support the development and implementation of costly technologies.

Not so in the food industry. That’s why more economical technologies to isolate and extract functional food ingredients are so eagerly sought by the industry today.

One such process for bioseparation is based on the 100-year-old technique chromatography. Long employed by the pharmaceutical industry but too dearly priced for the shallow pockets of food processors, chromatography boasts an impressive set of advantages in isolating component elements. First, it is reproducible. Second, it provides good resolution in separating desirable from undesirable components. Third, it is gentle on unstable target components.

The reason for optimism today is the promise of a continuous chromatographic process that is much less costly than the heretofore customary batch chromatographic processes.

The process currently is extracting dairy-based proteins and peptides from milk, colostrum and cheese whey. It also can fractionate dairy proteins into individual isolates, such as alpha lactalbumin and beta lactoglobulin. These whey proteins not only provide valuable functionality in the creation of gels, whips and fat replacers but seem to possess anti-inflammatory and anti-cancer properties as well.

Research has shown that another minor dairy protein, lactoferrin, has useful antimicrobial properties and benefits to bone growth and prevention of osteoporosis, in addition to anti-inflammatory properties. Lactoferrin also may aid skin growth and the healing of burns and wounds.

“We’re looking to leverage the platform for the dairy industry on the meat and horticultural waste streams,” says Geoffrey Smithers, director of international business for Food Science Australia, which provides research to food processors throughout the world. “And we’re looking at techniques to isolate antioxidants from fruit and vegetable streams. Continuous chromatography is the centerpiece of our bio-separation platform.”

Membrane-based techniques also promise rapid isolation of fine components.

“We are examining substitute membranes that will extract particles not just according to molecular size but on the basis of charge or hydrophobicity,” says Smithers. Different molecules, he explains, tend to partition into different types of oils – some toward fats, others toward more water-soluble oils.

Together these techniques may open cost-effective means of extracting plasma and its immunoglobulins and non-carrying transferrins.

On the plant side of the food world, the techniques may be used to isolate polyphenols and take advantage of their antioxidant properties.

Radio frequency

Conventional heating (conduction, convection, radiant) transfers heat from an external source to the surface of a food, which conducts the heat through to the center of the food.

Radio frequency is a different heating concept altogether, heating product at the molecular level from the surface and the center of the product at the same time. The industrial microwave has long played a role in processing plants.

That role, however, has been limited by the rate of penetration of microwaves and the uniformity of heat that microwave units provide. As consumers well know from their kitchen microwaves, part of the product can remain frozen while another part is overly hot.

Make way for radio-frequency heating.

“It’s still in the development stage, but with particulates, radio-frequency heating might better penetrate product,” says FPA’s Allah.

Work in RF sterilization is roughly at the same stage as high-pressure sterilization research, says Allah, and he sees its commercialization on roughly the same timetable.

Carbon dioxide extrusion

Extrusion is common practice in the manufacture of breakfast cereals, pet products, pasta and snacks. “But the extrusion process is a high-temperature, high-shear process. At up to 160°C, that is devastating to lots of nutrients,” says Sy Rizvi, professor at Cornell University’s Institute of Food Science.

Water, an essential ingredient in extruded food products, serves two functions, Rizvi explains: acting as a blowing agent, blowing material into a porous structure; and as a platicizer, converting a powder into dough. These roles are coupled. “You can’t change one without affecting the other,” he explains. “Too much moisture and the temperature won’t go up enough because you have too much liquid in the mix.”

To take on the challenge of balancing moisture and temperature, Rizvi and his colleagues aimed at decoupling the roles, using water as a plasticizer but not as a blowing agent.

His answer was using supercritical carbon dioxide and keeping the temperature during extrusion below 100°C. The process controls the number and size of cells by controlling the rate at which pressure is dropped.

“If there are a lot of small cells, the mechanical properties of the extruded material and its texture will be different – more crumbly and harder,” says Rizvi. “If you have a few big cells, the product will break easily.”

With CO2 extrusion, the process can be performed at temperatures of 40-90° C, well below water’s boiling point.

“At these lower temperatures, it is a good process for porous structure,” Rizvi goes on. “A lot of heat-sensitive ingredients can be added – proteins, flavorings, colorings and functional ingredients.” Rizvi and his Cornell associates develop the supercritical fluid extrusion (SCFX) process on a Wenger TX52 co-rotating, self-wiping, twin-screw extruder.

Two major advantages of the system are:

  • Secondary flavor deposition – With conventionally extruded products, flavoring is added after the rigorous process. The SCFX process enables the manufacturer to deposit flavoring materials into the material prior to extrusion, resulting in higher flavor impact.
  • Leavening without yeast – While water level must be carefully controlled in extrusion, CO2 can be used liberally. “You can get a leavened dough in two minutes,” says Rizvi. Normal yeast leavening may take up to four hours.

Rizvi is working with bakeries and dough makers to develop this leavening option.

“My dream is to see someone put this to work,” he says.

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