Welch's fills challenge of small plastic bottle: polypropylene 10-ounce bottles are selling well, but required a lot of adjustments on lines that had been used for glass - Welch Foods

Food & Drug Packaging, May, 2003 by Pan Demetrakakes

When you switch from glass to plastic bottles, you'd better be flexible.

Because the plastic bottles sure are.

Welch Foods illustrated that principle when it went from glass to plastic for its 10-ounce single-serve juice bottles. The transition, starting in July 2001, entailed many accommodations of the differences between glass and plastic. The lighter, more pliable plastic bottles presented numerous challenges in filling, handling, storage and other operational aspects.

The move seems to be paying off for Welch's. Sales of the 10ounce bottles have shot up since the transition was finalized in the spring of 2002. The facility at North East, Pa., which processes most of Welch's 10-ounce bottles, cranks them out 24 hours a day, six days a week. The product is so successful that Welch's was able to take up a temporary labor slack at a facility in nearby Westfield, N.Y., by sending it 10-ounce bottles for shrink wrapping (see "West field keeps labor gap under wraps" on page 54).

The basic motivation behind the switch from glass to plastic was relatively simple, says Ed Lerner, Welch's manager for R&D, package and process development: "It became very apparent plastic was a preferred container by the consumers."

The safety factor was especially important for juice, a product that appeals to children, says Hillary Keats, assistant brand manager. "It allows you to hit a full range of consumers, down to nine-, eight-, seven-year-old children whose parents wouldn't want to give them a glass container but would feel good giving them a plastic container," Keats says.

Why not PET?

Specifying the bottle material was the next step. Because the 10ounce bottle has a relatively high ratio of surface to product, a barrier is needed to keep out oxygen, Lerner says. The Welch's team considered different combinations of resins and constructions before settling on multilayer clarified polypropylene (PP) with a barrier layer of ethylene vinyl alcohol. The bottle is supplied by Pechiney Plastic Packaging. Juice in the bottle has a shelf life of more than six months (Welch's won't specify the exact period).

The major competing resin was polyethylene terephthalate (PET), which has better clarity than PP. However, many of the 10-ounce bottles are sold in shrink-wrapped multipacks, which lessens the importance of individual bottle clarity, says Bill Rungaitis, director of the Welch's facility in Lawton, Mich., where the 10-ounce bottles were first packaged before moving operations to the North East plant.

"This product is not being sold as an individual single product but as a case, and the consumers' sensitivity to the clarity of the bottle becomes far less important if you're selling a case versus an individual bottle," Rungaitis says.

The PP bottle's rigidity allowed it to make the transition from glass more easily than PET would have, Rungaitis says. Material handling required less adjustment: "When two bottles meet, they don't tend to bounce apart as much as the PET bottles do," he says.

Equally important was the resistance the PP bottle shows to the hot-fill process. It maintains its structure better than PET, and when it cools, the resulting vacuum doesn't compromise its shape as much.

"For the rest of the bottling guys out there in the world, if they have lines that are set to run glass bottles in hot fill, poly is a far better material than PET," Rungaitis says.

A tweak here, there, everywhere

Since the Lawton plant was the first Welch's facility to handle the 10-ounce PP bottle, it bore the brunt of the glass-to-plastic challenges. Although the rigidity of the PP bottle helped minimize those challenges, there still were plenty.

Lawton ran the new bottle on the same line that had been running 10-ounce juice in glass bottles. (That line still runs 16-ounce glass bottles, with changeovers taking place about eight times a month.) The only new piece of equipment required was a rotary screw-on capper, to replace the in-line capper that had been putting lugged metal closures on the glass bottles. But while most of the equipment stayed the same, it required plenty of tweaking.

"Although the [PP] bottle is better than the PET bottle in terms of its lack of deformation when it's hot-filled, there's still some sizing that has to be done," Rungaitis says. "It's not like glass, where no matter what you hit it with it's going to pretty much volumetrically stay the same. Any time you get into plastics, it's going to change slightly. So getting your volumes and your volume fills correct is something we had to go through a little trial and error with."

Welch's research and development department worked our the structural aspects of the bottle with Pechiney. But for the operational aspects of filling, there was no substitute for hands-on experience.

"We had to basically be the R&D pilot plant to define how much that bottle changes through the cooling process," says Stephanie Trevarrow, Lawton's plant superintendent.

Capping presented another challenge. Lawton personnel had to experiment with different materials and structures for the plastic closure and tamper-evident band, as well as the amount of steam applied to the closure at capping.