Dumping the can

Charlie the Tuna has been a household name since 1961, when he first helped peddle his finned kin as a popular lunch fish. “Sorry Charlie” was forever linked to the search for tuna, as TV announcers told the cartoon character that StarKist wanted tuna that tasted good, rather than tuna with good taste. Nothing, it seems, sells sandwich staples like a talking tuna.

But in modern supermarkets, Charlie may also become an unofficial spokesfish for North America’s plastics industry. His face, now printed on the side of stand-up retort pouches as well as cans, is marking the domestic emergence of a plastic-based packaging trend that has already proven itself in Europe and Asia.

It’s not the only offshore technology to creep into domestic pantries. A growing number of aseptic plastic containers are also taking their place on shelves. “We’re really just catching up to where Japan and parts of Asia have been for a number of years, and where Europe has gone ahead,” says Dow Chemical value chain manager Jeff Wooster, referring to domestic acceptance of the technologies.

Retort pouches challenging the incumbent cans

Retort packages come in virtually any shape, from pouches to trays and bowls, but the common denominator is that food is actually cooked in the package itself prior to reaching the retail shelves. Stand-up retort pouches have proven to be an attractive packaging alternative because of their bold look, long shelf life, and the promise of a fresher taste for low-acid foods (pH>4.5) because they can be exposed to less heat than cans when packagers are looking to kill bacteria.

The demand for retort pouches in the food and beverage market is actually expected to climb about 7% per year through 2006, according to the Freedonia Group, a research firm based in Massachusetts. “Pouches are replacing metal cans, paperboard boxes and other rigid containers, and in some cases bags, as producers choose more convenient and eye-appealing packaging to differentiate their products.”

Still, North American companies have been slow in their adoption of retort pouches. It’s difficult to justify replacing a quicker canning line, especially if it’s running at anything less than full capacity. And the use of pouches is accompanied by additional restrictions imposed by the U.S. Food and Drug Administration, which oversees everything from hermetic seals to extensive documentation requirements.

However, Marla Donahue, president of the Flexible Packaging Association, says the emerging category of “contract packagers” is helping to expedite the introduction of flexible designs of all sorts.

The retort packages themselves also have limits. The flexible containers can’t be heated over 250F, and packagers need designs that can handle the pressures created as foods are cooked. Even with the addition of aluminum foil in the final product, the packages don’t block out oxygen as effectively as metal or glass. Nor are the melt-bonded hermetic seals considered to be as reliable as mechanical double seaming.

But when retort packages are adopted, they have a big impact. Retort products shared the Flexible Packaging Association’s Highest Achievement Award this year, and dominated innovation categories.

Cryovac Simple Steps from the Cryovac Division of Sealed Air Corporation, for example, allows meat products such as stews to be cooked, shipped, displayed and reheated in the same package. A vacuum skin seal contours to the products, while a self-venting system allows the skin to expand when the package is re-heated, forming a bubble that vents and then relaxes over the food.

Materials and design are critical

The resins used in retort packages have to withstand abuse, cracks, pinholing, punctures, and must produce a strong bond that maintains strength at higher temperatures, says Dow’s Wooster. The containers are typically made from a combination of polyester, aluminum foil and polypropylene.

Recognizing retort pouches as a growth area, Dow plans to introduce Saran polyvinylidene chloride (PVDC) resin into the market.

“There are a few packages now that have a clear window or a clear back panel, for things like ready-made soup,” he says. “I think there are quite a few more of those types of products in development, and there are a number of technologies to facilitate the barrier-coated films.

“Saran has the advantage over some other polymers in that it is not moisture sensitive, so when you put a Saran film into a package, retort it or otherwise process at high temperatures … the barrier properties of the polymer are maintained.”

Aseptic breaks out of the box

Packagers across North America are now eyeing aseptic filling techniques for low-acid foods such as nutraceutical drinks (i.e. Boost and Ensure).

Through an aseptic process, products and their packages are sterilized independently and then assembled in sterile environments to control organisms that can contaminate food. The packages themselves tend to be sterilized with steam or chemicals such as hydrogen peroxide, the latter of which is used in the creation of Tetra Paks.

Whereas hot-filled bottles need to be accompanied by preservatives or ingredients to raise acidity, aseptic bottles can retain flavor and even allow milk to be stored outside the dairy case for more than a year.

And pasteurized products have already been identified as the next frontier, meaning that the future containers will need to withstand the pressure created when a bottle is filled with cool material, sealed and then heated.

Drinks, however, are only the first step. In a recent newsletter from the Closure Manufacturers Association, industry consultant John Tobias suggested that wide-mouth food jars could represent more than 3 billion conversion opportunities from traditional glass jars with metal caps.

“It is going to be an exciting year for the closure industry as we look at the potential for some retort packages coming out, some expanded use of aseptic packages,” adds Bill Thomas, director of product development for Silgan Closures. In fact, he suggests that 2004 will be the year that aseptic packages will emerge without inner seals made of induction foil.

Aseptic filling is not restricted to rigid containers. The Hershey’s Portable Pudding Stick Pack introduced by Curwood, Inc. is the first portion-controlled aseptic stick pack on the market. The new package uses a high barrier film that is cost-effective and easy to open, while relying on less storage space than cups. Related materials are almost half the cost of traditional cup/lid combinations. And graphics are improved since the entire stick pack incorporates reverse printing.

It seems that tuna may soon lose its prominence as the oft-cited example of plastic packaging’s latest catch. Sorry Charlie.

In-mold labelling: Looks better, sells better

In-mold labeling systems that put labels into the mold before injecting the resin are also making the trip to North America. The technology promises high-quality graphics integrated into packages, and higher process efficiency for molders who make the switch.

“We’ve believed for the last 15 years that eventually in-mold labeling would become a viable solution for North America,” says David Brown, CEO of Stack Teck. The Brampton, Ont. moldmaking company, which has partnered with Machines Pages Groupe FDP of Foncine Le Haut, France, showcased the process during NPE 2003.

“The restrictions have been related to volume,” he says. “The number of cavities running in a mold might be two-by-12, two-by-16, or four-by-16 — an incredible size of cavitation — so the ability to develop in-mold labeling technology for tooling of that size and that complexity was very difficult.”

But the company is now able to meet the needs of two-by-16 and two-by-12 molds.

“The obvious benefit is the graphics are incredibly superior to the normal offset printing that most packaging molders use today,” Brown says. “The in-mold product definitely shows better. In fact, we heard some studies done at a recent IML conference in Asia where the same product on the shelf –
– one was an in-mold labeled product, and the other without — the in-mold labeled package sold 25% more volume.”

Users also enjoy a lower scrap rate, he adds, using drink cups as an example.

“In the traditional process, you would mold the cup, warehouse the cup, take it out of the warehouse and print it, and then ship it. So you would have an incredible amount of time elapse from the first time that pellet enters the machine to the time that it gets shipped out the door.

“The scrap rates are very high because you have a molding scrap and you have a printing set-up scrap, sometimes as high as 5 to 7%,” Brown says. “With in-mold labeling, we’re seeing less than 2%, in some cases less than 1%. The advantage is you put the pellet of plastic in the machine, and when the cup comes out at the other end, it’s ready to ship. So your cash conversion cycle is much faster. You’re turning your inventory much faster.”

While IML is growing in acceptance, making it possible now to offer 3D images on plastic drink cups, high-volume production lines such as 96- and 120-cavity systems probably won’t be able to justify the additional price, he says.

John G. Smith is a business writer based in Ajax, ON.