Tamper-evident food packaging is taking on a higher profile as processors, retailers and consumers fret about the possibility of bioterrorism and other threats to the food supply. The costly problem of product damage caused by consumers opening packages to sample products also is fueling interest in tamper evidence.

Ames Int'l. uses some nontraditional tamper-proofing methods in its high-end gift candies. The acrylic jar is tamper-proofed by using a plastic "zip tie" that is looped through the clasp then hidden by a bow.

Shrink bands and tamper-evident seals and tapes continue to play an important role for packages ranging from single-serving containers to shipping cases. And in the future, radio frequency identification tags and light-emitting polymer technologies may step in next to these familiar devices.

The focus on tamper evidence is well founded. Malicious tampering can be incredibly expensive for the victimized company. In the early 1980s, Johnson and Johnson took a $100 million charge against earnings after voluntarily recalling its Tylenol products. Driving the recall was a tampering incident that left seven people dead from ingestion of cyanide-laced Tylenol capsules.

More recently, in Australia this summer, Masterfoods lost an estimated US $7.5 million when an extortionist claimed to have contaminated Mars and Snickers bars with pesticide. Masterfoods removed the chocolate bars from 40,000 stores in the Australian state of New South Wales.

Creative solutions

"There's always that fear" about malicious tampering, says Amy Paulose, director of marketing at Ames International Inc. (www.emilyschocolates.com), a Tacoma, Wash.-based company that sells chocolates and nuts. "The worst thing someone could do is put some kind of poison into food. There's also the question of how we keep people from stealing the product" from inside the package.

Ames uses many types of packaging, including conventional polyethylene terephthalate (PET) and acrylic jars as well as novelty packages such as Chinese take-out food boxes and cloth dolls. The company uses a variety of tamper-evident techniques to accommodate the breadth of containers.

For canisters and jars, Ames applies an induction seal across the mouth of the container. For boxes of chocolates, shrink wrap provides evidence if the packaged is opened.

Protecting seasonal, gift and novelty packaging requires more creativity, both because the container shapes are unusual and because the items are produced in small batches. Product volumes don't support an investment in automated tamper-evident packaging equipment.

For Ames' gift jars of chocolate-covered fruits and nuts, a plastic zip tie is manually looped through the clasp of the jar's lid and concealed with a bow. The zip tie locks the lid; opening the jar requires cutting the zip tie.

The company thwarts tampering with its snowman-doll package by borrowing technology from the garment industry. A pouch of chocolate-covered nuts resides in the body of the doll, and the head pops off. The company locks the head onto the body using the same kind of plastic loop used to attach price tags to clothing.

Shrink bands expand

For high-volume products such as beverages and processed grocery items, shrink labels and bands remain a favorite tamper-evident tactic for unit-level packaging. The bands typically are made of shrinkable polyvinyl chloride (PVC), glycolized polyester (PETG) or oriented polystyrene (OPS).

A transparent tamper-evident band, which is part of the full-body shrink label, wraps over the lips of the twin shake and pour spouts on the lid of General Mills' Betty Crocker Decorating Decors package. Photo courtesy of Seal-It Inc.

"Tamper evidence has become bigger and bigger," says Sharon Lobel, president and CEO of Seal-It Inc. (www.sealitinc.com), a Farmingdale, N.Y., maker of heat shrink labels and films. "If you were to walk into a supermarket years ago, there might have been a few items that had a tamper-evident band, mostly vitamins. Now most of your food items have a tamper-evident band. And the bands are more elaborate as time goes on, especially in food."

General Mills Inc. (www.generalmills.com), Minneapolis, uses a full-body shrink label for its Betty Crocker Decorating Decors packaging. The label incorporates a transparent tamper-evident band that wraps over the lip of the twin shake and pour spouts on the lid. Seal-It supplies the Decors labels.

More processors are striving for tamper-evident bands that coordinate with or even merge with the label's graphics. Stallone's Italian Kitchen (www.stallones.com), Deerfield Beach, Fla., took this approach for its salad dressing packaging.

Stallone's uses brightly printed, full-body shrink labels on glass bottles. Supplied by Seal-It, the PVC labels are rotogravure printed in 10 colors. The label incorporates a tamper-evident seal with a horizontal perforation. When the perforation is broken, the seal is removed and the label remains on the bottle.

Shrink bands are finding their way into applications far beyond bottles and jars, as well. With more produce marketers entering the fresh-cut segment, tamper-evident bands are becoming commonplace on thermoformed trays of salad mix and pre-cut vegetables and fruit.