"A customer told us, 'You don't know what that means to me, being able to sleep at night,'" McCann relates. In a trial involving a pallet load of bacon placed in a HPP unit and subjected to 85,000 psi of pressure, only one of 1,944 packages leaked.
Seal integrity is a concern with most containers, a point underscored by March's recall of 2.4 million cans of tuna produced at Bumble Bee Foods' Santa Fe Springs, Calif., facility. If a metal seal can be compromised, the vulnerability of polyethylene or other film material is obvious.
Jeff Almond credits film companies for material improvements that are improving seals and driving down processors' costs, particularly in high-speed applications. End seals that used to be in the ¾- to 1-in. range have shrunk to ¼ to ½ in., reports the snack food industry manager for packaging at Heat and Control Inc., Hayward, Calif. On a single bag, the reduction seems insignificant, but reducing the endseal and backseal on an form/fill/seal bag is a major savings for packagers, Almond says.
Those cost savings pale in comparison to the promise of ultrasonic sealing, however. That technology exists primarily in prototype mode, although Bosch Packaging Technology unveiled the SPC 4020 vertical filler with ultrasonic sealing technology at 2012's Anuga Foodtech show in Cologne, Germany. "It is more sophisticated, better technology (than heat sealing), but it requires a bigger (capital) investment," according to Martin Dupick, Bosch's global product manager-VFFS product line.
SPC is shorthand for SurePouch Clean-fill, a series of four flexible pouch formats, including pillow packs and block-bottom bags. The sealer's vibratory action cuts through any food on the sealing service, resulting in a tighter seal and fewer package rejects. Dupick says the seal surface is only 2.5 mm -- less than 1/10th of an inch -- which reduces film costs.
"You can quickly create a business case with an ROI of three months to two years," he says. The downside is lack of industrial hardening: "If you do something wrong with ultrasonic sealing, you can damage the sealer," he allows. "With heat sealing, you can operate pretty brutally."
SPC is rated as an ultraclean system, a notch below aseptic. Dairy drinks, noncarbonated beverages, soups and low-viscosity dressings can be filled at a rate of up to 60 bags per minute (bpm). One U.S. client has converted to ultrasonic sealing, Dupick says, "but the majority of the (customer) base isn't ready to make the switch yet."
SPC's run rate is sluggish compared to less sensitive products such as potato chips, where gravity is a bigger limitation than machine speed. For lightweight products, the focus has shifted to filling gaps between existing high- and low-end systems, not faster fill rates.
Heat and Control's decades-long collaboration with Japan's Ishida Co. Ltd. has helped the companies attain a dominant position in the packaging of dry products, particularly snack foods. The precision of Ishida's scales to drop product into an form/fill/seal machine with little giveaway made it a standard. Heat and Control's expertise in processing and product handling enabled the firm to design turnkey systems that deliver product to those scales and then to the bagger and beyond.
Intermittent motion sealers with a nominal rating of 100 bpm dominated vertical form/fill/seal until the mid-1990s, when adjustments to scale height enabled continuous motion sealers, such as Ishida's Atlas 223 bagmaker. The machine's twin rotary jaws are rated at 200 bpm. A huge gap existed between the 223 and Ishida's base unit until the recent introduction of the Atlas 233, a continuous motion single-jaw sealer designed for potato chips and similar products. The 233 operates in the 80-120 bpm range. "If you're not doing automated pack off, it doesn't do you any good to have a machine (like the 223) that produces 150 bpm," Almond points out.
Just as the throughput capacity of fryers and roasters dictates how quickly form/fill/seal machines should operate, secondary packaging should be able to keep pace with bagformers. That's not always the case, however, as Wornick Foods discovered when attempting to dry gusseted foil pouches for military MREs (meals ready to eat). Condensation from the retort simply couldn't be thoroughly evaporated from the nooks and crannies of the pouches' folds, resulting in water stains and eventual weakening of the cardboard boxes used for shipping, according to Scott Lynn, eastern regional sales manager for JetAir Technologies LLC, Ventura, Calif.
Physics pointed to the solution. Instead of conveying the pouches through drying tunnels fitted with air knives, JetAir engineered an 8-ft.-long compartment with air nozzles. "Because the nozzles project air better than a knife, they do a good job of penetrating into the gusseted areas," says Lynn. VFDs on the 20 hp high-speed centrifugal blowers improve energy efficiency compared to the 15-ft.-long tunnels that the system replaced. More significantly, the system dries 200 pouches per minute, double the tunnels' throughput. Since the first installation in 2009, Wornick has commissioned four more units.
Bottlenecks can occur anywhere on a packaging line, and improvements in one area tend to shift the chokepoints to another. It may look like a game of whack-a-mole, but it's all in the interest of faster, better, cheaper.
This article originally appeared in our June issue of Food Processing magazine.