Tech Update: Aseptic processing and packaging: two peas in the continuous pod

January 1, 2007
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Whether finished goods are shipped chilled or at ambient temperature, aseptic technology is gradually expanding its foothold in the US market.

Consumer preferences for plastic containers is driving some of the development at aseptic packaging suppliers more closely associated with paper-based containers. Source: SIG Combibloc Inc. 


The product isn’t aseptic, but wine in aseptic paperboard containers is emerging as an application star for the technology. Source: Tetra Pak Inc.

Mix and match

As the Aurora Organic project demonstrates, contemporary processors are not bashful about taking the best of current technology and discarding capabilities that don’t fit their business model. Besides the plate-steam injection system, the dairy is leveraging a synergistic package decontamination system that uses concentrations of hydrogen peroxide and ultraviolet light. Exposure to UV light generates antimicrobial radicals from peroxide, according to Gunnar Rysstad, a microbiologist with Elopak.

Typically, heat and a solution of 35 percent hydrogen peroxide are used to sterilize containers feeding into aseptic fillers. With UV, peroxide concentration can be scaled back to 5 percent to achieve a 5-log Bacillus subtilis spore reduction, Rysstad says. Peroxide residues also are reduced.

Residues are a non-issue if electron beam treatment is used instead of peroxide. The world’s first e-beam decontamination system was demonstrated in November in Japan on a 600-bottles-per-minute (bpm) filler by Shibuya Kogyo Co. Ltd. “The initial cost of the machine is comparable to a hydrogen peroxide system,” says Yoshi Izumi, an engineer who now serves as executive vice president at Shibuya Hoppmann Corp., Elkland, VA. “Operating cost is very low compared to chemical systems, and residues are zero.”

With more than 35 high-speed aseptic fillers in commercial use in Japan, Shibuya is one of the world leaders in this segment. Last year, a 1,200 bpm system for juices and low-acid teas came on line at Nihon Canpak in Tonegawa, Japan. Shibuya’s 600 bpm filler at HP Hood’s Winchester, VA, dairy became the first FDA-approved rotary filler for low-acid beverages when it was validated in April 2005. HEPA filters were relocated to the top of the machine, eliminating much of the piping found in the Japanese version and reducing the potential contamination points.

Despite the regulatory milestone, the Hood installation remains one of only two aseptic Shibuya fillers in the US, including a high-acid system for juice at a Mott’s plant in Aspers, PA. “Less than five low-acid systems a year are being installed, and few manufacturers are installing high-speed machines,” notes Izumi. “We still hope low-acid beverage filling will grow, but it’s a pretty limited market now.”

While the firm marks time waiting for healthy tea (vs. sugar- and preservative-heavy hot-fill tea) to emerge as a US mass-market beverage, it is increasing its presence in the pharmaceutical industry with innovations such as a high-speed vaporized H2O2 decontamination system. It also is leveraging the expertise of Hoppmann Corp., which it acquired in 2005, to extend its aseptic integration capabilities to include bottle-feeding and assembly systems. Currently Tetra Pak is alone in its ability to deliver a front- to back-end system, though manufacturers are as inclined to mix and match as they are to seek a turnkey solution. Just as Tetra Pak’s aseptic processing technology is paired with Elopak fillers and packaging at Aurora Organic, Hood’s Tetra Pak processors feed into Shibuya and Serac fillers.

Other than their temperature profiles and instrumentation, very little distinguishes an aseptic processing system from an ESL pasteurizer. In fact, many European aseptic pasteurizers and fillers are operated as ESL systems in the US. The added time and expense to secure FDA approval still work against aseptic validation. Given consumer expectations of chilled product, the savings from aseptic tend to be limited to distributing products at ambient temperature instead of refrigerated. Most manufacturers conclude the savings don’t justify aseptic’s validation costs and delays. However, the emergence of alternative distribution channels such as vending may make aseptic more attractive. “The market is moving toward aseptic,” insists Tetra Pak’s Berlan.

Both ESL and aseptic require higher skill sets for operators and maintenance staffs. Tetra Pak installed a commercial scale line in its Greenwood, IN, fabrication plant to provide hands-on training for manufacturing teams. “Training was probably our biggest challenge,” allows Aurora Organic’s Wilson. “Finding qualified people to operate and maintain the system was a huge difficulty.” Operators with experience on conventional pasteurizers have walked away rather than undergo retraining.

New-to-the-market products and ingredients are causing processors to specify system features that were unusual or unheard of a decade ago. Aseptic dosing systems to introduce heat sensitive ingredients and enzymes post sterilization is one example; another is energy conservation programs that throttle down throughput if water is being used to maintain sterility while awaiting filling machine availability.

 Microfiltration with ceramic filters is being used in Canada and Europe to reduce plate counts to near sterility, and a US dairy has joined its European counterparts in applying bactofugation, the purification technology that relies on centrifugal force to separate components of similar size but different densities. Both techniques are designed to separate desirable and undesirable elements. “Five to 10 years from now,” one technology vendor predicts, “there will be a technology available for aseptic filtration.”

Instant sterilization with steam injection (pictured) and infusion systems is gaining traction with premium ESL and aseptic products. Source: FMC FoodTech.

Infusion vs. injection

With the right sanitary gaskets and fittings, almost any heat exchanger can produce UHT or aseptic products. As a practical matter, high-quality products have been processed primarily with steam injection, the technology that injects steam directly into the product for instant sterilization, then removes the steam under vacuum in a flash cooler. Run times between CIP are much longer than with plate or tubular heat exchangers, and product degradation is considerably lower.

Flash coolers paired with steam injectors that can process up to 250 gallons of product per minute (GPM) are likely to be mounted outside a food plant. The smallest flash cooler made by FMC FoodTech handles 35 GPM throughput. Source: FMC FoodTech.

A growing number of manufacturers are gravitating to infusion systems. Though more expensive and less energy efficient than injection, infusion reduces the likelihood of product over-heating and is gentler than injection, proponents argue. In a comparison of the technologies, Elopak’s Rysstad concludes Delta T during final heating is more precise with infusion, pressure drops in the holding tube are tempered and product contact with steel surfaces is lower, resulting in less fouling. Milk infusion also has been shown to deliver higher levels of Beta-lactoglobulin, a desirable protein, and lower levels of Lactulose, an undesirable sugar molecule.

With steam infusion, product moves under vacuum through narrow tubes in a steam chamber, then into a flash vessel. Sterility is achieved in 0.2 seconds, though by regulation hold time is 0.5 seconds. “It’s a simpler, less punishing way to sterilize the product,” maintains Paul Knoerle, sales director at APV Invensys. “You get a fresher taste and fewer off flavors, particularly with the soy milk products.”

Ten years ago, APV introduced Pure-Lac, an infusion system that combines microfiltration to remove almost all of the bacteria from low-fat milk, thereby extending shelf life. While the infusion system has been reengineered for easier cleaning and other improvements, microfiltration is technology still waiting in the wings for US regulatory approval. In the meantime, APV is concentrating on interfacing with new filling and packaging systems. “A lot of the business drivers are the extended shelf life plastic bottles,” explains Knoerle.

Those drivers are reflected in the development work in plastic bottles and filling systems by aseptic paperboard fabricators SIG Combibloc and Tetra Pak. SIG Asbofill GmbH’s linear aseptic fillers, which can output 12,000 bottles per hour, have been augmented with a neck handling system that conveys a variety of shapes and sizes, from 250 ml to 2 liters, with minimal changeover. The system uses sterile air and hydrogen peroxide aerosol to replace wet container sterilization.

Cartons still are Combibloc’s heart and soul, and the supplier scored an aseptic coup with the August 2005 rollout of Campbell Soup’s Select Gold Label, the first FDA-approved low acid food with particulate. Instead of filling through a tube, product is deposited through a nozzle while the container is in a 1-sq.-meter aseptic zone, explains Oliver Bittner, marketing director at SIG Combibloc Inc., Columbus, OH. The nozzle can handle food chunks up to 15-mm (1.2-in) thick and fibers up to 40-mm long.

Combibloc’s filler is fed by a tubular heat exchanger fabricated by FMC FoodTech, Madera, CA. Dimpled tubes with a hygienic static mixer to boost turbulence are at the heart of the processing system.

Steam injection isn’t an option with preformulated soups, but FMC FoodTech offers injection with aseptic tomato paste processors. It would require 1,000 psi/g to pump a product as viscous as paste through a tubular system, says Jun Weng, FMC’s research fellow. With steam, 90 gallons a minute can be processed. When the paste enters the flash chamber, vacuum drops the temperature from 210

The difference between low-acid extended shelf life (ESL) and aseptic product is like bologna: how thin do you want to slice it?

ESL and aseptic are technological twins and an enabling science to move food companies from batch to continuous processing. Even when manufacturers decide against validating equipment as aseptic, they can tap into the production advantages and higher hygienic standards delivered by the technology-and a growing number are doing just that. Regardless of how the finished goods are presented to consumers, aseptic processing, filling and packaging technology gradually is inching toward the commercial mainstream.

Cartoned table wine is a quirky example. While aseptic bag-in-box for multi-liter presentations found a niche years ago, wine in aseptic paperboard containers only now is bursting on the North American scene. Three packaging facilities dedicated to filling table wine in Tetra Pak Prisma and Brik containers came on line in Canada last year, and a California plant should join the North American mix by mid-2007. “The interest in aseptic for wine is exciting, but it’s also frustrating because we don’t have the capacity to meet demand,” says Debbie Dawson, director-new business development and emerging markets in Tetra Pak’s Denton, TX, facility. Pacific Natural Foods in Tualatin, OR, and California Natural Products in Lathrop, CA, began copacking cartoned wine in 2006, but demand exceeds what they can deliver, she says.

Worldwide, more than 1.5 billion Tetra Pak containers are filled with wine each year. A third of Italian table wines are sold in paperboard containers, and at least half of the wines in Argentina and Chile are filled in multi-ply paper and foil packages. Australian producers also are flocking to aseptic, according to Dawson. “Every winery is looking for new occasions for wine and to make the product more approachable,” she says. “The shelf appeal of aseptic containers is astonishing.”

Of course, aseptic processing would ruin wine, and nothing more severe than a nitrogen sparge is used to maintain cleanliness at the filler between CIP cycles. Still, the packaging application helps advance the technology by expanding the number of manufacturers with aseptic systems and justifying additional development spending by equipment suppliers.

Technology overkill also occurs in the processing area, though aseptic helps manufacturers deliver higher quality, premium priced products, even if the equipment is commissioned for ESL production instead of aseptic. The differences in mechanical features and skills needed to operate an ESL and aseptic pasteurizer are minimal or nonexistent. Depending on the range of products a processor hopes to produce, systems are being engineered to perform both direct and indirect heating of fluid products. For example, the Tetra Therm Aseptic Flex system can incorporate plate, tubular and direct heat exchangers to deliver regular pasteurization, ESL or aseptic. 

The soy milk segment has generated considerable interest in direct-heat aseptic processing, both steam injection and infusion. Tetra Pak added infusion to its technical capabilities in the last 5 years, according to Jean Pierre Berlan, director-sales & marketing of Tetra Pak’s processing division. The sensitivity of soy demands advanced heat treatment. Finished goods are sold both as ESL and aseptic.

A Tetra Therm Aseptic VTIS 100 system was installed two years ago at Aurora Organic Dairy. The system boasts a plate heat exchanger and a steam injection unit to produce either HTST and UHT milk, depending on whether retailers want regular pasteurized or ESL organic milk. Although similar steam injection units produce aseptic product elsewhere, the Boulder, CO, dairy’s system does not. “Over 95 percent of the milk in this country is sold as pasteurized or ultra-pasteurized; there is no aseptic organic milk,” explains Clark Driftmier, Aurora’s senior vice president of marketing. Retailers position Aurora’s products as premium private-label products in their dairy cases, and none are interested in pioneering ambient temperature organic.

When planning the plant’s design, Jay Wilson, Aurora’s senior vice president-operations, toured breweries and beverage bottlers for processing and material-handling ideas for continuous production flow. “We come out of the raw silos and standardize the milk on the fly, without batching anything,” says Wilson. Finished product is filled on P-H9OUC Elopak machines that fill 150 half-gallon Pure-Pak cartons a minute, “significantly faster than any previous machines in dairies,” he adds. “We’re pushing the envelope in terms of line speed.”

Elopak aseptic fillers are being used with refrigerated liquid eggs from Michael Foods and Papetti’s. Private-label liquid eggs are grabbing space in grocers’ coolers nationwide. Marketing eggs and milk as ESL instead of ambient is probably a healthy trend, suggests Nils-Erik Aaby, senior vice president-packaging for Elopak Americas Inc., New Hudson, MI. He cites the negative impact aseptic milk had in many European countries after its introduction 20 years ago. Until manufacturers mastered UHT processes, the milk often suffered from off flavors. Initially priced at a premium, UHT’s burned flavor turned off a generation of children to milk. The product also led to commodity pricing that eroded margins. “American management, to its credit, has understood that when you make a technology decision, there are strategic implications,” Aaby says. “They listened when consumers said, ‘We want fresh, cold milk and juice.’”

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