s c i e n c e / t e c h n o l o g y

IN DEFENSE OF FOOD Packaging shifts from passive protection to active role in improving food quality

Sophie L. Wilkinson C&EN Washington

R 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 Ther-on W. Downes, packaging profes- <§| sor at Michigan State University, East Lansing. The market is domi­nated by paper and paperboard (including shipping containers and folding cartons), followed in de­creasing order by plastics, metal, glass, and other containers.

The industry is consolidating but is still fragmented, with the rigid food container market alone served by about 500 companies, says Freedonia Group, a Cleveland consulting firm. The industry in­cludes numerous players who tend to fo­cus on just one or two sectors, and each sector possesses a unique character.

In the plastics business, for example, resin producers may either make their own films or sell their resin to a convert­er who makes film and prints it, says Bruce R. Harte, director of Michigan State's School of Packaging. That roll stock then goes to a food manufacturer who shapes the film into the desired package form and fills it. Many food companies purchase resin to make their own plastic bottles. Some food firms also make their own cans, or they may buy them from can manufacturers. Likewise, food companies can obtain either finished paper-based containers from a converter, or they may

Ready-to-eat contents, minimized packaging, and convenient operation epitomize food-packaging trends.

buy roll stock or paperboard to make their own. Glass producers melt their raw materials, form them into bottles, an­neal and coat them, and forward them to food manufacturers.

Semirigid plastic and flexible packaging are taking over an increasing share of the

packaging market from glass jars and met­al cans, according to Aaron L. Brody, man­aging director of Rubbright Brody, a Du-luth, Ga., consulting firm that serves the food-packaging technology and marketing arenas. Demand for glass, cans, and paper-board 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 in­surmountable: Focus groups have shown that a white interior coating made from ti­tanium dioxide-pigmented epoxies gets positive consumer feedback. And Budway points out that "the can is still a great package—it is tamper-resistant and it has as long, if not longer, shelf life than many other packages out there."

Another strike against the can is a cus­tomer perception of "flexible, PET [poly­ethylene terephthalate], and glass as be-

26 JUNE 15, 1998 C&EN

Paperboard leads rigid food container sales

Glass Paperboard 12% 39%

1997 U.S. demand = $11.6 billion

Source: Freedonia Group

ing a little more sexy and the can being not as modern," Budway says. "New packaging sparks new interest."

Indeed, food companies are relying more than ever on novel packaging to dif­ferentiate products from their competi­tors', through graphics and structure, con­venience, and how the packaging can be used, Rimes says.

American National Can and Aurora Foods recendy teamed up to create a poly­propylene bottle for Log Cabin brand syr­up that features rounded logs and a chim­ney, intended to "convey the image of hearth and home goodness" to customers, says Edward T. Yuhas, consumer market­ing director for Aurora's breakfast foods di­vision. "It is a highly visible means of brand differentiation."

Distinguishing features can be more than cosmetic. Zippers can be incorporat­ed into a package so the consumer can re-close it, for example, or a package can be designed so the consumer can reheat the food in either a conventional or micro­wave oven, Rimes says.

Passive packaging Consumers reap benefits from all these

packaging developments in terms of user-friendly containers, longer product shelf life, and convenient ready-to-eat foods. But packaging developers aren't resting on their laurels. "Everybody keeps looking for the elusive perfect material," Harte says. "But it has not yet been found."

Until recently, the emphasis has been on "passive barriers," which "just sit there and act as a barrier between the environ­ment and the product," Hotchkiss says.

Such materials are often mixed to take advantage of desired properties. Ap­pearance can be deceptive in these cas­es. "You might pick up a piece of film

and it looks like it's one layer, but in fact it might be five, six, seven, eight, or nine layers of different plastics, all very thin," Rimes says.

These polymer combinations can yield better barrier and structural properties, Risch says. As a result, "companies are able to make the materials thinner gauge and still have them perform as well," she says.

Examples include flexible "high-barri­er" materials that greatly reduce the rate of oxygen transfer to the food, such as squeezable ketchup bottles. There are a number of such bottles available, but the first breakthrough type consisted of two layers of polypropylene attached by "tie layers" (proprietary adhesive-like materi­als) to an inner barrier polymer layer of ethylene vinyl alcohol, Hotchkiss says.

France's Pechiney and the U.K.'s Bass Brewers recendy came out with a beer bottle made of ethylene vinyl alcohol sand­wiched between two PET layers. Based on technology developed by Pechiney subsid­iary American National Can, the bottles give the beer a shelf life of at least 12 weeks, Pechiney says. That exceeds the six-week shelf life typical of other plastic-bottled beers, Bass notes.

Other passive materials, such as plasti-cized polyvinyl chloride (PVQ, slow mois­ture loss while letting oxygen pass through. This is useful for products like red meat, which needs oxygen to maintain the bright red color that consumers associate with quality. Meanwhile, the moisture barrier prevents the meat from drying out in the case, Hotchkiss says.

Packaging improvements are boosting the distribution of case-ready meats, "prepared not in the back room of a su­permarket but in USDA-inspected facto­ries and delivered to the store prepack­aged," Brody says. These centrally pre­pared, modified-atmosphere packages provide economies of scale and cleanli­ness advantages, DuPont's Rimes says.

Cryovac, Duncan, S.C., has developed a package for this market that incorporates an oxygen-barrier lidding material on a barrier foam tray to extend shelf life, says Dee Reviere, Cryovac's North American marketing director for case-ready prod­ucts. The packages are evacuated and then flushed with nitrogen and carbon dioxide prior to shipment. When retailers are ready to put the meat in the retail case, they peel off the lidding material, expos­ing an oxygen-permeable layer. This per­mits the meat to turn from the purplish color characteristic of a low-oxygen envi­ronment to bright red.

With ground beef packaged this way "we are gaining 16-plus days of shelf life in the barrier format," Reviere says. "Once you peel it, you get two days." These stats compare with about a day of shelf life for ground beef packaged by retailers in tradi­tional PVC wrap.

Oxygen and moisture aren't the only substances that must be kept on the ap­propriate side of a package. Flavor and aroma barriers are becoming more neces­sary as more products are sold in conve­nience stores, Risch says. "We're seeing complaints where products are picking up off flavors." Crackers, for example, can pick up flavors from laundry detergent across the aisle, she says. "And you also of­ten have gas pumps outside, so you have low-level gas fumes. So packages are being developed to make sure that you keep the good flavors in and bad flavors out." These materials could be polyester or oriented polypropylene metallized with a thin coat of aluminum.

There are numerous other possible packaging combinations. Materials such as PET, nylons, and polypropylenes are being coated with silicon or aluminum ox­ide to create barriers for oxygen and or-ganics, Harte says. These are suitable for products such as cooked meat and sauces or microwave foods. And Michigan State packaging professor Jack R. Giacin and as­sociate professor Ruben J. Hernandez are evaluating clay-polyimide nanocomposites as barrier materials for oxygen, carbon di­oxide, and water vapor.

Eye-catching container design draws consumers.

JUNE 15, 1998 C&EN 27

Metal 28%

Plastic 21%

science/technology

Other relative newcomers in food packaging include polyethylene naphtha-late (PEN) (C&EN, Nov. 10, 1997, page 8) and PEN-PET blends used as high-bar­rier films or rigid containers, Harte says. Suitable for such products as beer bottles and other typical PET applications, these materials serve as a substantial barrier to oxygen and flavors. Risch says PEN is ex­pensive but "has much better heat resis­tance, strength, and barrier properties than plain polyester film."

Mobil and other firms are making ori­ented high-density polyethylene—which normally isn't produced as an oriented material—to create a water-vapor barrier "as good or better than oriented polypro­pylene," Risch says. "And they are able to metallize it with aluminum and get an even better barrier."

DuPont is developing its new Versipol catalyst technology to make improved polyolefin materials, including polyethyl­ene resins with unique characteristics, Rimes says. The technology uses a low-pressure reactor to make highly branched polymers that generally require high-pressure reactors, which are more costly to run. It can also incorporate polar comonomers such as acrylates and esters to make polar ethylene copolymers under these conditions, "and that's a departure from what could be accomplished be­fore," Rimes says. In the food market, these materials could be used in heat seal and adhesive layers in flexible packaging.

The company recently broadened its Surlyn product line with two resins to be used as sealants for cheese or poultry packages. These ethylene methacrylic acid copolymers incorporate zinc or so­dium cations to make them into iono-mers, Rimes says.

The sealant for cheese packages bests the oxygen leakage rate of the previous sealant, ethylene vinyl acetate, by at least half, "resulting in much greater packag­ing reliability for the packager" and re­duced problems with mold, Rimes says.

The poultry sealant is used for turkey breasts cooked within the film that is used to display the meat at deli counters. The sealant serves as the inner layer of this film, and it bonds to the turkey to prevent meat juices from leaking out dur­ing cooking.

Active packaging As these examples show, "we have a

large number of materials and the ability to combine them in a lot of different ways to produce passive barriers," Hotchkiss says. "But my crystal ball says we are near-

FDA: Watchdog at the border between food and packaging Premarket approval from the Food & Drug Administration is required for any material that may become a component of food Because chemicals can migrate from packaging into food, this gives the agency jurisdiction over food packaging. In fact, about 60% of FDA rulings concern packaging, says Joseph H. Hotchkiss, professor of food science and toxicology at Cornell University. "They spend more time reviewing packaging regulations and issues than they do food," he says.

Manufacturers rarely market products that are unsuitably packaged, according to Timothy H. Begley, team leader of FDA's indirect additives lab in Washing­ton, D.C. But if they do, the agency may find out about it through "company espio­nage, where one company says someone else is out of compliance with the law."

Typically, a packaging manufacturer or user must present FDA with data showing that use of a proposed material is safe, says George H. Pauli, director of FDA's Division of Product Policy in the Office of Premarket Approval in Wash­ington, D.C. Such determinations are af­fected by the composition and structure of the package (surface-to-volume ratios affect transfer quantities); the chemical nature of the food (if it is fatty, for in­stance); the preparation and processing

techniques (if it is held at high tempera­ture for an extended time, as in can­ning, for example); and the public's consumption levels.

To evaluate transfer of packaging chemicals into food, Begley's lab typically uses model systems with food-simulating solvents such as water/ethanol or food oils. The simulations overestimate migra­tion as compared with actual food prod­ucts, he says. The increased sensitivity of the lab's analytical methods, compared with those used in years past, means FDA is "now able to detect some components which we didn't know about before," Pauli says.

One group of chemicals drawing the public's attention is endocrine disrupt­ers, which mimic or interfere with estro­gen and other hormones. Bisphenol A is one example. "These chemicals are usual­ly found in polycarbonates or epoxy can coatings, and there are also some plasti-cizers used in wraps and films," Begley says. Although they have been detected in some food samples, "we find only very few parts per billion migrate into food under normal conditions." Pauli says health effects of such chemicals are un­clear at this point and merit further study, though "at this stage we know of no safety problems for humans."

ing the end of that road. The next step is going to be 'active' packaging."

Active packaging works in concert with the food product and its environ­ment to produce a desired effect. Instead of the packaging simply providing a barri­er to protect the product, it plays an active role in maintaining or even improving the quality of the enclosed food.

The possible permutations on this theme are endless. Hotchkiss has immobi­lized the enzyme naringinase—which breaks down flavonones that produce bit­terness in citrus products—in a polymer that could potentially be used as a liner in­side a grapefruit juice carton. When the juice is stored in contact with the film, the enzyme hydrolyzes the bitter compounds, making the beverage taste sweeter over time.

He is also developing antimicrobial packaging. "Surface growth of microor­ganisms is one of the leading causes of food spoilage," according to Kay D. Cook-sey, associate professor of packaging at the University of Wisconsin, Stout, in Menomonie, Wis. "A packaging system that allows for slow release of an antimi­crobial agent into the food could signifi­

cantly increase the shelf life and improve the quality of a variety of foods." And in applications calling for packages that must currently be sterilized before filling, such as aseptically filled beverage containers, self-sterilizing packaging could be a boon.

Numerous potential antimicrobials are under study. Cooksey recently finished an evaluation of nisin—an antibiotic pro­duced by Lactococcus lactis—coated onto low-density polyethylene film in a methyl-cellulose carrier. Other antimicrobials that have been studied include naturally de­rived agents such as benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, and propionic acid. Some have been used in edible coatings.

Allyl isothiocyanate, an antimicrobial plant extract approved as an additive in Japan, diffuses from packaging as a vapor and can extend the shelf life of meat, fish, and cheese. Researchers have also incorporated zeolites in packaging to re­lease silver ions, or enzymes to release such antimicrobials as hydrogen perox­ide, Cooksey says.

Despite the industry's best efforts, mi­croorganisms will continue to crop up in food. Several researchers are working on a

28 JUNE 15, 1998 C&EN

detection system for bacterial toxins and pathogens in food, according to University of California, Berkeley, chemistry profes­sor Raymond C. Stevens. His team is devel­oping a system that "uses cell mimics engi­neered to promote color changes in the presence of pathogens in food." If such a system were integrated into the packag­ing, this color change could alert the con­sumer not to eat the food.

Another way to alert consumers to problems is with time-temperature indi­cators, which can show whether the en­closed frozen or refrigerated food prod­uct has been mishandled during shipping or storage. The devices won't be success­ful in the U.S. food market unless their prices drop and suppliers figure out how consumers can read them, Brody says. The devices also need technology to pre­vent an indicator from triggering a false alarm "when the sun shines on it for 30 seconds."

Perception of fresh While such techniques are clearly ben­

eficial, some active packaging may go too far in terms of what it implies about the nature of its contents. "Are you in any way deceiving the consumer?" Risch wonders. For example, a zip strip could be incorpo­rated in a package to release a fresh aroma of the product when the package is opened, she says.

"People want to consume more prod­ucts that are perceived as fresh," Hotch-kiss says. But are the products as fresh as the public believes?

One example is fresh pasta—high-moisture-content pasta placed in a carbon dioxide-nitrogen atmosphere within a moisture-barrier package to extend shelf life to about six weeks. Such packages may include packets containing propri­etary iron-based compounds, which essen­tially "rust, absorbing oxygen out of the package," Hotchkiss says.

Sales of other fresh products such as lightly processed packaged vegetables in­cluding peeled baby carrots and pretorn salads, have really taken off, Hotchkiss says. Prepackaged pineapple and apple slices are also turning up in stores.

The modified-atmosphere packaging, with high oxygen and carbon dioxide permeability, gives these products 14 days of shelf life, Brody says. "Can you hold a head of lettuce for 14 days? No. You would throw out lots of lettuce."

The package has to be breathable, be­cause the cut produce continues to re­spire, emitting gases. "If those gases built up inside, they would spoil the produce,

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so they have to permeate through the packaging," Risch explains.

These packages may contain potassi­um permanganate adsorbed onto silica or other inorganics to absorb ethylene and retard ripening, Hotchkiss says.

Such convenience foods are part of a larger movement at grocery stores, which are increasingly offering refrigerated fin­ished meals that contain several different foods in the same package. This trend to­ward home meal replacements "will prob­ably cause some substantial changes in how we retail food, and that may cause some substantial changes in how we pack­age food," Harte says. "We may have to have packaging that provides protection and compatibility differently, depending on what is in the master pack or master pouch, which may contain five or six dif­ferent products."

As food products become more com­plex and comprehensive, so must their packaging. "One of the things you see a lot more of today is 'system integration,' where you are looking at a marriage of two or three or four packing processing technologies," Harte says. "You might

have a modified-atmosphere package of produce that can be cooked in the pack­age in a microwave. Or you might have an aseptic package that is also micro-wavable." The food could even be irradi­ated in the package to sterilize it and ex­tend its shelf life, though this brings up the issue of the effect of radiation on the package material itself, Harte notes.

For that matter, many of the new food processing and sterilization techniques, such as high pressure, ultrasound, and magnetic treatments, "will require some research into which packages are the most appropriate and how the packages are affected by these new processes," Harte says.

Companies are also reassessing the inter­action between microwaves and packag­ing. "We had a rush in the late 1980s where everyone just slapped 'microwavable' on every product and disappointed the con­sumers—it was horrible," Risch says. "Now, companies are cautiously going back to looking at microwave products and under­standing that packaging is a key component of making microwave products work." The problem is that "companies have not

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wanted to pay," she adds. "They usually say the packaging cost has to be a minor component of the cost of the product."

Eat it all One way to cut back on cost is to cut

back on packaging. Many current packag­es are multilayer, including perhaps a moisture barrier, an oxygen barrier, and other layers for strength, printing, and so forth. "If you could eliminate the need for an oxygen barrier or an aroma barrier, and if you could get away with just a simple moisture barrier package, it could be not only simpler and cheaper, it could be recy­clable," says John M. Krochta, professor of food science and technology and profes­sor of biological and agricultural engineer­ing at the University of California, Davis. (Multilayer packages, which are hard to separate into their components, are less likely to be recyclable, he notes.)

This can be done by substituting edible coatings or films for some of the conven­tional packaging. However, these materi­als will not replace conventional packag­ing entirely. "You still need to protect the food from contamination and have a way to contain and market the food," Krochta says.

Edible coatings, film wraps, and pouch­es are made from proteins, polysaccha­rides, and lipids. Additives to improve functional properties include plasticizers such as polyols and lipids, and emulsifiers such as mono- and diglycerides and leci­thins, according to Jesus A. Quezada Gallo, a graduate student in the food science de­partment at the University of Burgundy, Dijon, France.

Edible coatings can protect food from oxygen to prevent oxidative rancidity, prevent aroma loss to preserve flavor, and maintain optimum moisture content, Krochta says.

Gallo treated dry cookies, which tend to lose crispness once they are removed from their plastic packaging, with a coating based on gluten and margarine. Lab tests showed the coating slowed water absorption, boost­ing shelf life by at least 30% under severe, high-humidity storage conditions.

Another niche for edible coatings is in keeping high- and low-moisture ingredi­ents apart within a food product. "If you want to make a refrigerated pizza, you have to keep the high-moisture-content to­mato sauce from migrating to the low-moisture-content dough," Hotchkiss says. "If you don't do that you end up with a wet rag. So one of the ideas is to develop a barrier film that will inhibit transfer of moisture. You can cover the top of the

3 0 JUNE 15, 1998 C&EN

baked pizza dough with that film and then put the sauce on top of that."

Krochta's work has focused on whey protein (isolated from whey, a by-product of cheese manufacture). Whey protein coating acts as an oxygen, aroma, and oil barrier. This can be useful as a nut coating to prevent oil migration into other ingredi­ents in confectionary products and baked goods, Krochta says.

Whey protein can also boost structur­al integrity of foods. "A lot of dry foods are very fragile, and during handling and transportation they tend to start disinte­grating," he says. His experiments with edible whey coatings on freeze-dried diced chicken, used in products such as dry soup mixes, showed that the coat­ings can "dramatically reduce that kind of damage. And at the same time we are protecting the food from oxygen."

Eventually, "it is possible that we could make film wraps and small food pouches for dry-food mixes from such films. They would act mainly as oxygen and aroma barriers, and they would go into another package like a moisture barrier film such as low-density polyethylene. The inside pouch, made of whey protein, would dis­integrate or dissolve when you added boil­ing water to it, and become an edible part of the food," Krochta says.

Krochta is working with other edible films, including ones based on soy protein. Other researchers are working with corn zein (a corn protein), wheat gluten, and polysaccharides such as modified starch, carrageenan, chitosan, and cellulose deriv­atives. Gallo says proteins and polysaccha-

Modified-atmosphere packaging keeps pasta fresh,

rides show good mechanical and sensory properties and serve as a good barrier against gases and aroma transfers, whereas lipids are the best moisture barrier.

Edible films could conceivably be used in active packaging, Krochta says. The films can incorporate natural antimicrobi­als such as sorbic acid or natural antioxi­dants such as ascorbic acid (vitamin C) and tocopherols (which make up vita­min E) to prevent the contained food from being oxidized.

Waste not, want not Edible films cut back on the packaging

waste stream, but they aren't suited to all food products. Another environmentally friendly solution is biodegradable packag­ing. The challenge manufacturers face is to

§ ensure these materials a> have the "appropriate | strength and will last long "5 enough that they don't | start degrading before the <§ end of their useful life,"

Risch says. Eastman Chemical re­

cently introduced a com-postable plastic, Eastar Bio copolyester, which can be used for food packaging. The polymer combines strength and moisture resistance, and is similar to low-density polyethylene. It can be used as a paperboard coating or combined with materials such as starch

and wood flour. When composted, it "breaks down to carbon dioxide, water, and biomass at a rate comparable to news­paper," according to Joost Berting, prod­uct launch manager for biodegradable products. He expects the polymer to do well in Europe, where "composting is an acknowledged form of recycling."

Recycling must be done with care. Ma­terials that are returned to the raw materi­al supply chain rather than composted can create a safety concern, Risch says. "If you are going to take these materials back into something that is going to be in contact with a food product, how will we guaran­tee that they have not been contaminat­ed?" Recycling of fiber-based materials in­creases the microbiological load, particu­larly bacterial spores, Hotchkiss adds. And

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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

Cookies protected with an edible coating stay crisper Water gain in 25-g cookies, g 4(

Hours of storage at 25 C and 100% relative humidity

first typically a tin or titanium oxide coat­ing that is deposited at elevated tempera­ture. It acts as an adhesive for an organic coating such as polyethylene that gives the bottle lubricity and strength. Manufactur­ers would like to cut costs by using just one coating and are experimenting with a poly­meric silane material that can be cured by heat or ultraviolet light. Unfortunately, the method is expensive and the coating must be applied in a controlled environ­ment (such as nitrogen), Davis says, but the technique shows some advantages.

For example, UV inhibitors can be add­ed to enhance content protection (neces­sary for foods such as beer, yogurt, and milk), a function currendy served by am­ber and green glass. Colorants can also be incorporated. The theory, says Davis, is that "there would be no more colored glass. Everything would be made in clear glass and you would overcoat it with whatever color you wanted." And that would do away with the cost of color-sort­

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 pa-perboard 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 by fillers and 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 lam­inates are replacing rigid folding cartons for applica­tions such as beverages, Gor­don says.

Growth areas for paper include blister packaging, where paperboard with a plastic blister over it is used to hold products such as cold cuts. Gordon says stores like these because they can be hung on hooks and wall displays, expanding store shelf space. Paperboard is also making inroads in super­

markets' preprepared foods, such as whole roasted chickens. And the growth of super­stores, which sell products in corrugated boxes that hold multiple packages, are also extending demand.

Paper and paperboard lend themselves to printing and graphic presentation. Print­ing is currently done in a separate step from application of oxygen or moisture barrier materials, but converters are con­sidering combining the two steps, Gordon notes. "Since paper or paperboard has to be printed anyway, why not put that barri­er coating on using the printing press?"

Clearly, there are numerous packaging materials and designs for food companies to choose from, and once they do, they don't have the option to just leave well enough alone. "On average, most new food packag­ing ideas have a shelf life—an effective com­mercial life without changing—of about three to five years," Gordon says. As shelf space becomes ever more scarce, he says, "this is going to become even shorter."^

With coating

Without coating

Loss of crispness