Enhancing Food Security Through Packaging

Michael Kelly, Robert Steele, Andrew Scully, Michael Rooney Packaging Material Development Section Food Science Australia North Ryde NSW 2113, Australia

INTRODUCTION

In light of the current political environment there is an increasing need for enhancement of food security. This need places extra demands on the packaging industry to deliver new and improved tamper-resistant and tamper-evident packaging systems. Almost all commercially available tamper-evident packaging currently relies on the physical destruction of a tamper-evident feature. The design of such features must take into account the physical strength of consumers in order to minimize inconvenience, especially elderly or disabled consumers.

The FDA has defined a tamper-resistant package as "one having an indicator, or barrier to entry, which if breached or missing can reasonably be expected to provide visible evidence to consumers that tampering has occurred". The ability of manufacturers, retailers and consumers to detect tampering with current tamper-evident packaging systems cannot be assumed.

The limitations of existing tamper-evident packaging, and new approaches that will overcome some of these limitations, will be discussed. In particular, a new concept which provides clear visual evidence of tampering, and which can be incorporated into an indicator layer within the packaging structure, will be presented.

FOOD SECURITY

One of the primary roles of packaging is to protect food from unintentional contamination by food spoilage agents such as dirt, microbes, insects, oxygen and water by preventing their access to the inside of the package. More recently, the need has arisen for packaging also to be capable of protecting the contents from intentional contamination, or tampering.^1-3

The tampering of Tylenol^® capsules in the USA in 1982 resulted in seven deaths, and prompted the U.S. Food and Drug Administration (FDA) to introduce legislation (21 CFR 211.132, 700.25 and 800.12) requiring tamper resistant packaging for over-the counter (OTC) pharmaceuticals, cosmetics and medical devices in the United States, but no equivalent legislation exists for the packaging of food. Nevertheless, duty-of-care obligations dictate that manufacturers must ensure that food products are safe when purchased by the consumer,⁴ and the FDA has issued a recommendation⁵ that food manufacturers should adopt a HACCP protocol that includes provision for use of tamper evident packaging.

The Proprietary Medicines Association of Australia (PMAA) has stated¹ that it is not possible to produce a package that is tamper-proof, and any suggestion that a package is tamper-proof is deliberately misleading. Instead, the PMAA recommends that the terms tamper-evident or tamper-resistant should be used. The FDA regulation for packaging of OTC pharmaceuticals states that "a tamper-resistant package is defined as one having an indicator or barrier to entry which, if breached or missing, can reasonably be expected to provide visible evidence to consumers that tampering has occurred."

The least malicious type of tampering is that by "human grazers" who open packages in-store to either taste or eat products without purchasing. While for many foods this does not pose a serious safety threat to the final consumer, there is a finite risk if the product was originally sterile and tampering has compromised this sterility. Usually, it is obvious if a package on the store shelf has been opened previously for the purpose of human grazing, and it is unlikely that the product would pass unnoticed by the retailer or purchaser.

In contrast, intentional tampering of food poses a real safety threat to consumers. In this case, products are contaminated by incorporation of a dangerous substance or item intended to cause harm to the consumer. The motives for deliberate contamination of food products include;

• Political
• Extortion (for monetary or other benefit)
• Revenge against a company, retailer or person
• Concealment of another motive, such as murder, suicide, etc.
• Monetary gain other than extortion (e.g. selling the story to the media)
• Attention (e.g. through the media)
• Notoriety through copycat tampering

TAMPER-EVIDENT PACKAGING DESIGN

Johnson reported results of experiments on the effectiveness of 94 tamper-evident devices.⁴ All devices were reported to be easily defeated using low-technology tools, with the cost of equipment to defeat the seals averaging $56. The mean time taken to defeat the devices was 4.3 minutes, and in all cases independent security experts were unable to find evidence of tampering. For devices costing more than $US 1, adding an extra $US 1 to the cost of the device increased defeat time by 1 second. Even devices
costing less than $US 1 still required about 4 minutes to defeat. This finding indicates that many current tamper evident packaging devices are unlikely to deter a determined perpetrator.

Factors that need to be considered in the design of effective tamper-evident packaging include;

• Length of time required to breach the package
• Expense and sophistication of equipment required to breach the package
• Likely method of breach of package integrity
• Point in the distribution chain where tampering occurs
• Point in the distribution chain where detection is implemented
• Clarity and type of indication of tampering required
• Degree of protection of contents
• Ease of opening by consumers
• Irreversibility of tamper evidence
• Ease of copying
• Compliance with any regulations or guidelines

PACKAGES REQUIRING CLOSURE INTEGRITY INDICATORS

Entry to glass containers, such as bottles and jars, is usually through the lid or cap. The food industry voluntarily introduced tamper evident packaging for these type of containers, predominantly in the form of mechanical indicators such as ring caps, shrink sleeves, extended labels, breakable rings, button lids and separating collars. Deficiencies in these devices exist⁴, such as the ease with which shrink sleeves can be softened, removed and re-applied, and the re-activation of button-lids by re-applying under vacuum.

PACKAGES REQUIRING WHOLE-SURFACE INTEGRITY INDICATION

Plastic bottles
Unlike glass containers, entry through the body of a plastic container is possible. The devices mentioned above for glass containers can help in highlighting entry through the lid but not the body of the container. To protect the integrity of plastic bottles, a system is required that reacts to entry into the bottle at any point. One approach to this is that described in the patent of Perlman and Linschitz⁶, in which an oxygen sensitive indicator is sealed into the lid of the bottle, where the bottle or jar is gas flushed to remove oxygen. While the oxygen level in the bottle is very low the indicator is colourless. When the bottle integrity is breached at any point, oxygen enters the bottle and the indicator changes colour revealing a message indicating a fault with the product to the consumer. Shrink wrapping entire bottles with film imprinted with holograms,^7,8 pressure-sensitive inks,^9-11 brittle^12-14 or optical indicators^15-20 are other alternatives that have been proposed.

Thermoformed trays
Thermoformed trays have become more prevalent for packaging of chilled foods such as fresh meat, pasta and convenience meals. Entry into trays can be either through the lidding or the body of the container, and so it is important to have a system that secures the entire pack.

Oxygen indicators, such as tablets or labels, incorporated into low-oxygen MAP trays to indicate pack integrity are also able, under certain conditions, to provide evidence of tamper.¹³ If the gas composition inside the pack changes such that the oxygen level inside the pack increases, then the indicator changes colour, thereby indicating loss of integrity of the pack and possibly the safety of the food. This is the only commercially available tamper-evident packaging system that is potentially capable of conveying information about the status of the entire pack rather than just the seal or closure.

Flexible pouches
Flexible pouches are possibly the simplest package to tamper with and constitute the greatest challenge to designers of tamper-evident systems. Mechanically based tamper-evident systems cannot be readily applied to flexible pouches and so appropriate tamper-evident devices for such packaging are scarce and expensive.

Concepts that have been proposed to indicate breach of package integrity other than at the package seals include;

• A brittle layer in a laminated structure that changes colour when stressed.^12-14
• Micro-encapsulated inks that are released when the film is stressed or ruptured.¹⁰
• Holograms incorporated into laminated films that disappear when stressed or ruptured.^7,8
• Incorporation of a hygroscopic substance in a layer of a laminated film,²¹ where liquefaction of the hygroscopic substance (eg. calcium chloride) occurs when the integrity of the laminate is breached.
• Optical layers that change colour due to stress or rupture^12-14 as a result of changes in refractive index of the film.

Many of the above concepts require some form of structural rigidity, which is prone to damage during transportation and storage. A tamper-evident system must be able to distinguish between damage arising during transportation that has not resulted in the loss of integrity of the package, and damage resulting from tampering which has compromised the integrity of the package.

THE FUTURE

Consumers require reassurance that packaged foods are fit for consumption, and the packaging itself can provide the vehicle to convey this information, as demonstrated through the use of "use-by" and "best before" date stamps, and mechanical tamper-evident devices that protect the integrity of closures for rigid containers. However, tamper-evidence solutions for flexible packages remain scarce, despite the relative ease with which these packages can be tampered and the point of entry concealed. Research is being carried out in Food Science Australia, and elsewhere around the world, to develop indicators that are potentially capable of detecting and reporting loss of integrity at any point in the entire pack.

REFERENCES

1. Tamper Evident Pressure Builds, Pack, pp. 13-19, December 1991
2. Tamper Evidence in the Nervous Nineties, Food & Pack pp. 28-33, August 1997
3. Arnott's Threat Invokes Tamper-Evident Debate, Food & Pack pp. 6, April 1997
4. Jack L. Rosette, Improving Tamper-Evident Packaging, Technomic Publishing Company Inc. 1992
5. FDA, HACCP Guidelines, Annex 5.
6. Perlman; Daniel, Linschitz; Henry, USPatent 4526752: Oxygen indicator for packaging.
7. Bartlett, Jr; Oliver, Izard; Charles, US Patent 4200394: Hologram technique forestablishing the integrity of packaging.
8. Kay; Ralph, US Patent 5319475: Tamper resisting holographic security seal.
9. Hoffmann; Donald, Chang; C, US Patent 5970875: Pressure-sensitive tamper evident system.
10. Resnick: Joseph, US Patent 4424911: Container tamper detection device.
11. Cornell; Lew, US Patent 3935960: Tamper indicator tape.
12. Curiel; Yoram, US Patent 4945708: Method of making a tamper resistant package.
13. Wang; Alan, US Patent 5137208: Tamper evident package.
14. Decker; Thomas, US Patent 6033762: Self-adhesive resealable tamper-evident tape.
15. Gosselin; Raymond, Spielbauer; Thomas, US Patent 6004656: Color changeable device.
16. Brochman; Wilfred, US Patent 3923198: Stress-opacifiable tamper indicator.
17. Schaefer; Richard, Tome; James, US Patent 4557505: Stress-opacifying tamper indicating tape.
18. Schrenk; Walter, Shrum; William, Wheatly; John, US Patent 4937134: Elastomeric optical interferance films.
19. Wheatly; John, Schrenk; Walter, US Patent 5149578: Multilayer film for tamper indication by use of optical interference reflection.
20. Versic; Ronald, Emrick; Donald, US Patent 5234732: Tamper-indicating wrappers.
21. van Blerk; Victor, US Patent 4839752: Temperature/humidity floppy disk cassette defeat mechanism.

BIOGRAPHIES

Michael Kelly is a Packaging Consultant at Food Science Australia. He has worked in the packaging industry for the past 17 years. Five years with a large flexible packaging converter and 12 years with Food Science Australia. He is involved in developing new packaging technologies and consulting to industry. Current research project is on tamper evident packaging.

Bob Steele is a Project Leader in the Packaging Material Development Section at Food Science Australia. Ha has over 30 years experience in the packaging industry. His interests range from thermal processing to the study of the interactions between foods and their packages.

Andrew Scully joined Food Science Australia's active and intelligent packaging research group in Sydney 1997, where he now heads the Packaging Material Development Section.

Michael Rooney is a Research Fellow at Food Science Australia. He specialises in product/packaging interactions, active packaging - especially oxygen removal, permeability and modified atmospheres.