Good Enough to Eat

9 November 2009 (Last Updated November 9th, 2009 18:30)

With concerns over bacterial infection more prevalent than ever, food packaging firms need to come up with new solutions. Dr Gareth Evans looks at how cardboard candy and tasty tetrapacks could be the very thing of the future.

Good Enough to Eat

Consumer demand is arguably the most influential factor that shapes the direction of packaging technology – and consumers are notoriously fickle. It is inevitable that today's growing public desire for healthier lifestyles and more ecologically sound products should drive a shift in packaging trends, especially for the food industry.

Prolonging the life of foodstuffs, maintaining product quality and meeting customer expectations, while still making a profit, places significant constraints on packagers and producers, particularly when it comes to developing novel approaches to packaging.

The current iteration of these converging and, at times, conflicting demands predicates packaging which is effective and essentially recyclable, if not completely biodegradable. As a result, many in the industry predict that edible coatings will increasingly become the way of the future.

If so – and some of the ideas that have emerged from research laboratories around the world do ultimately translate into commercial reality – the new technology could change the face of food and packaging forever. The next generation of food wraps will, it seems, not only protect foodstuffs from damage, prevent spoilage, extend shelf-life and improve their appearance, they will help to kill bacteria and add flavour too.

Antimicrobial coatings

The idea is an intriguing one. Although the antimicrobial properties of many plant-derived essential oils have long been recognised and there is nothing intrinsically new about edible coatings, combining them into naturally bactericidal food wraps holds enormous promise for the industry.

"Many in the industry predict that edible coatings will increasingly become the way of the future."

Said to be the first time that plant oils and edible coatings have been incorporated in this way to benefit food safety, work by a team from the US Department of Agriculture and Spain's University of Lleida provides perhaps one of the clearest views of the technology's potential. Having first demonstrated that thin films of apple puree had no antibacterial action, their study examined the effectiveness of plant oils in coating solutions made from fruit or vegetable purees and as dried films,with some remarkable results.

The investigation tested varying concentrations of cinnamon, lemongrass and oregano oils against a potentially fatal strain of the Escherichia coli bacterium, E. coli O157:H7. The team found that although all inhibited growth, but oregano oil was by the far the most effective. According to Tara McHugh, the project's lead researcher, in laboratory tests coatings impregnated with oregano oil were shown to be capable of killing more than 50% of the bacteria within three minutes at concentrations as low as 340 parts per million (ppm).

Although oregano is the active ingredient, the sticky nature of the apple-based film provides its own benefits to the coating, allowing it to bond effectively onto the surface of the food and ensuring that bacterial contact exposure to the antimicrobial it contains is maximised.

Predictably, any foods coated are going to have a bit of an 'apple-and-oregano' taste, but with the initial target use being as a spray-on application for salads and vegetables, this could prove a positive marketing asset. These coatings can be made based on a wide range of other fruit and vegetable purees – including the likes of broccoli, carrot, mango, tomato, peach or pear – so achieving a suitably complementary flavour should present few technical obstacles to commercial use.

"Coatings impregnated with oregano oil were shown to be capable of killing more than 50% of the bacteria within three minutes."

There is no shortage of other research projects also looking into this area. Films and coatings have been produced from cellulose, starch, gluten, soy, milk proteins and mesquite gum, with antimicrobial ingredients ranging from thyme to cloves and paprika. Much of this work still remains in its early stages, though the successes to date have been decidedly encouraging.

If new types of edible coatings can be developed – to be used on highly perishable foods, to form flavour-enhancing glazes when cooked or that can supplement the vitamin or mineral quality of food, for instance – and made properly market-ready, their future will be very exciting.

Coated boxes

This potential could, however, take a while to be realised. More traditional approaches to packaging are likely to be around for some time, but here too developments in coating technology play a major part in addressing the needs of changing times and evolving consumer demand.

Wax-coated corrugated boxes, for example, have been one of the conventional mainstays for a range of perishable foods for many years but concerns regarding the recyclability of packaging are leading many retailers and processors to look for alternatives. The presence of such coatings effectively rules out re-pulping the paperboard, typically making it impossible for producers or their customers to dovetail into existing local recycling arrangements, while consigning waste cartons over long distances for retreatment is itself scarcely a sustainable option.

Water-based barrier coatings could offer one potential solution to the problem, although the often highly specific needs of individual food producers means that there is seldom a simple, "one-size-fits-all" answer to be had.

It is an area that coatings companies such as Ohio's Michelman have identified and prioritised, particularly in respect of meat packaging, providing a range of suitable barrier technologies to ease the transition from waxed boxes without compromising performance.

"The key to meeting packaging requirements of a wide range of products effectively lies in providing coatings that are tailored to meet specific user demands."

Michelman's experience suggests that the key to meeting packaging requirements of a wide range of products effectively lies in providing coatings that are tailored to meet specific user demands, with an emphasis on custom formulation to optimise the fit. Unsurprisingly, the company places much store on technical innovation, along with an employee base that includes a healthy contingent of formulators and application specialists, to ensure that all those needs are met.

Even under the best of economic circumstances, the food and packaging industries face a significant challenge in marrying the often near-irreconcilable demands of consumer preference, product integrity and profitability. Moreover, as the Food Technology Intelligence report, 'New Packaging Technologies For The Food Industry - 2009 Edition' makes clear, "complicating these issues for food companies are the costs of implementing new technologies aimed at meeting these demands".

That said, it is hard to imagine how the recent developments within coatings technology can fail to have significant ramifications for the industry as a whole, assuming that they successfully make the jump to commercial viability. There are, after all, few more effective ways for any company to get ahead of its competitors than by optimising its product packaging.