science/technology packaging market from glass jars and metal cans, according to Aaron L. Brody, managing director of Rubbright Brody, a Duluth, Ga., consulting firm that serves the food-packaging technology and marketing arenas. Demand for glass, cans, and paperboard is stalled, while plastic and flexible packaging use is growing, says Brody, who is also an adjunct professor at the University of Georgia, Athens, and Saint Joseph's University, Philadelphia. The trend is driven both by cost and functionality, Hotchkiss says. Consider ketchup, for example. "Ketchup is very oxygen-sensitive, and it must have a very high [oxygen] barrier material in order not to darken and solidify," he notes. Glass can fill the bill, but "people like ketchup in a squeezable bottle. That is a function you can't get with glass." Oxygen permeability is an issue with plastic beer bottles, too. "Oxygen gets in and makes the product go bad, whereas you don't have that with glass," says Sara J. Risen, whose food and packaging development consulting firm, Science By Design, is based in Chicago. On the other hand, plastic takes up less room, weighs less, and doesn't break. That's particularly attractive for beer sales at sporting events and concerts, where plastic bottles do away with "all that potential for broken glass around," she says. Glass isn't the only sector where flexible packaging is making inroads. The food service industry—restaurants, cafeterias, hospitals, and institutes—is particularly partial to flexible pouches as a substitute for cans, says Andrew E. Rimes, DuPont's senior development programs manager for packaging and industrial polymers. "They provide ease of opening—you don't have to worry about opening a can—and disposal is a lot easier." The can also suffers from consumers' impressions about canned food, including that "the [interior] coating doesn't look good, and they think that affects the flavor," says Robert R. Budway, president of the Can Manufacturers Institute, Washington, D.C. "We know that's not true, but the perception is there." But this isn't inReady-to-eat contents, minimized packaging, surmountable: Focus groups have shown that a white interior coating made from tiand convenient operation epitomize tanium dioxide-pigmented epoxies gets food-packaging trends. positive consumer feedback. And Budway buy roll stock or paperboard to make points out that "the can is still a great their own. Glass producers melt their package—it is tamper-resistant and it has raw materials, form them into bottles, an- as long, if not longer, shelf life than many neal and coat them, and forward them to other packages out there." Another strike against the can is a cusfood manufacturers. Semirigid plastic andflexiblepackaging tomer perception of "flexible, PET [polyare taking over an increasing share of the ethylene terephthalate], and glass as be-
IN DEFENSE OF FOOD
Packaging shifts from passive protection to active role in improving food quality Sophie L. Wilkinson C&EN Washington
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ed wines and some aged cheeses are just about the only packaged food products that get better as they get older, says Joseph H. Hotchkiss, professor of food science and toxicology at Cornell University. "But beyond that, virtually all food products deteriorate over time." Packaging researchers are developing technology to slow that deterioration and, in some cases, to enlist the packaging in actively improving food quality. Food and beverage packaging account for about 70% of the $100 billion to $110 billion packaging market 1] in the U.S. and more than half of | j the $400 billion worldwide packaging business, according to Theron W. Downes, packaging profes- yw'Zf'ifpw
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science/technology ing glass prior to recycling, because the color coating could simply be burned off when the glass was melted. Recycling, source reduction, and cost issues are also shaping the paper and paperboard market. "Paperboard packaging will be getting smaller as food companies reformulate their foods into concentrated form," says Robert L. Gordon, research fellow in International Paper's packaging development unit, Tuxedo, N.Y. Dehydrated soups are one example. And for products like frozen entrees, the outer folding carton is being eliminated, leaving simply a tray and lid. Lighter weight paper and paperboard with the same physical properties as heavier versions are being developed, made possible byfillersand composites such as polymers and cellulose, Gordon says. In some cases, one form of paper packaging is giving way to anoth' er. Flexible, stand-up pouches made of paper-plastic lamCookies protected with an inates are replacing rigid edible coating stay crisper folding cartons for applications such as beverages, GorWater gain in 25-g cookies, g don says. 4( Without coating Growth areas for paper include blister packaging, Loss of crispness where paperboard with a plastic blister over it is used to hold products such as With coating cold cuts. Gordon says stores like these because they can be hung on hooks and wall Hours of storage at 25 C displays, expanding store and 100% relative humidity shelf space. Paperboard is also making inroads in superfirst typically a tin or titanium oxide coat- markets' preprepared foods, such as whole ing that is deposited at elevated tempera- roasted chickens. And the growth of superture. It acts as an adhesive for an organic stores, which sell products in corrugated coating such as polyethylene that gives the boxes that hold multiple packages, are also bottle lubricity and strength. Manufactur- extending demand. Paper and paperboard lend themselves ers would like to cut costs by using just one coating and are experimenting with a poly- to printing and graphic presentation. Printmeric silane material that can be cured by ing is currently done in a separate step heat or ultraviolet light. Unfortunately, from application of oxygen or moisture the method is expensive and the coating barrier materials, but converters are conmust be applied in a controlled environ- sidering combining the two steps, Gordon ment (such as nitrogen), Davis says, but notes. "Since paper or paperboard has to be printed anyway, why not put that barrithe technique shows some advantages. For example, UV inhibitors can be add- er coating on using the printing press?" Clearly, there are numerous packaging ed to enhance content protection (necessary for foods such as beer, yogurt, and materials and designs for food companies to milk), a function currendy served by am- choose from, and once they do, they don't ber and green glass. Colorants can also be have the option to just leave well enough incorporated. The theory, says Davis, is alone. "On average, most new food packagthat "there would be no more colored ing ideas have a shelf life—an effective comglass. Everything would be made in clear mercial life without changing—of about glass and you would overcoat it with three to five years," Gordon says. As shelf whatever color you wanted." And that space becomes ever more scarce, he says, would do away with the cost of color-sort- "this is going to become even shorter."^
it also reduces the quality of the fibers, leading to a loss of strength. Glass, on the other hand, can be recycled indefinitely without loss of quality, says Michael W. Davis, research group department manager at American Glass Research, Butler, Pa. The glass industry is incorporating an increasing percentage of recycled glass in its products and is developing methods to simplify recycling, he adds. (The Glass Packaging Institute notes that average recycle content is more than 25%.) And new equipment, plungers, and molds, as well as computer-aided design techniques, are resulting in lighter weight containers, Davis says. Glass is a mature industry, but producers continue to seek out technological improvements, including those for surface treatments. Davis says that nonrefillable bottles currently receive two treatments, the
