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In many ways, the ‘Love Food Hate Waste’ campaign from the Waste & Resources Action Programme (Wrap) is about consumer education. As a nation, we are sloppy in every department, from storing the food we buy to estimating the quantities we cook.

But although ‘Love Packaging Optimisation’ may be less snappy, this theme also has to be central to the campaign. Alongside portion control, attention needs to be focused on the gamut of technologies, some of them fast-evolving, which can lengthen the shelf-life of different foods. Many of the most exciting techniques are being applied to flexible plastics.

The Integrity Seal project originally interested Wrap as a route to material savings. Developed by International Food Partners in collaboration with Ceetak, the technology eliminates the excess film on the outside of a traditional crimp-end seal. Trials with Marks & Spencer demonstrate that this change, plus the potential for using thinner-gauge film, can translate into a pack weight reduction of up to 25% on products such as salads.

But since many packs incorporating a crimp seal are not airtight, Wrap now also cites Integrity Seal as an example of a technology that can enhance shelf-life. Project manager Andrew Parry says: “Now the project has progressed to the back-seal on form fill seal lines. This is mainly being applied to fresh produce, although United Biscuits has been looking at it for baked goods, for instance. There’s still work to do on line speeds, but factory trials are under way now and by the second quarter of 2008 there should be a system to create a fully hermetic bag.”

And the logic behind a project such as Integrity Seal doesn’t end there. “Once there is real potential for a cost-effective all-round hermetic seal, then it becomes more worthwhile for food companies to invest in improved materials and other shelf-life-enhancing technologies such as modified atmosphere packaging (MAP),” Parry explains.

Watching brief
Wrap is keeping a careful watch on other projects, too. Parry points to trials using a micro-perforated film for fresh produce, involving Tesco and converting partner Amcor Flexibles. “There’s potential to extend shelf-life by up to three days,” says Parry. But he adds: “We want to do consumer research, logging food waste, because we all assume that three extra days of shelf-life will actually reduce wastage.” These research findings will be eagerly awaited – and not only at Tesco.

For additional benefits, permeability can be combined with other tailored attributes in a film or pack. Long Life Solutions (LLS) has rigid and flexible variants of its Smart Technology, which includes the Smartbag. This interactive packaging concept was launched around seven years ago, says chief executive Andrew Wright. “We claim to have the most permeable film in the marketplace today, combined with a membrane that manages the gas exchange and an active agent that inhibits the growth of microbes,” he says. The technology is typically used for fresh fruit and vegetables.

LLS appears to be having real success in the Americas, where produce ranging from blueberries to bananas is benefiting from the interactive concept. In the process, it is opening up accounts with growers that could reach millions of dollars a time, Wright claims.

Closer to home, the company is working with the Co-op on products including cucumbers. Here, Smartliners in the bulk corrugated case replace individual shrink packs on each cucumber. Tests have shown that this “will not impact on shelf-life”, says Wright. It will also eliminate an estimated eight tonnes of packaging a year, the company adds.

LLS is cagey about the antimicrobial system it uses. Wright dismisses agents such as copper that work only in direct contact with the product requiring protection. He will only say that LLS’s chosen agent is a “natural food extract” (see sidebar).

Bulk and item versions of the LLS Smartbag have typically been based on polyethylene film, says Wright, but a biodegradable version will be available for the first time next year.

Biopolymers have had a rough ride in recent months over their performance in the supply chain. But Innovia Films, which makes the NatureFlex range of cellulose-based products, emphasises the valuable role that these new materials can play in certain applications. Market development manager Andy Sweetman says: “In our case, the cellulose has relatively good gas barrier characteristics, but a poor moisture barrier. With unprepared fruit and vegetables, packaging that allows moisture to pass through is an advantage. There are definite indications of improved shelf-life, although we have nothing quantified yet.”

Moisture and gas management
As well as moisture management, NatureFlex films can be micro- or macro-perforated for gas management.

More complex structures involving biopolymers are also becoming more common. Sweetman gives the example of a film, which recently won an industry award, used by Jordans for its organic muesli and granola products. “This is a laminate of NatureFlex on the outside, acting as a ‘bio-PP’ or transparent print web, moisture and gas barrier, and Mater-Bi on the inside, offering high heat-seal strength and high tear resistance, much like a ‘bio-PE’,” he says. This is said to be the first European biopolymer laminate – and the first that combines products from different suppliers.

Sweetman argues that, if the product to be protected does not absorb much moisture from the air, for instance, NatureFlex and other biopolymers can satisfy both performance and sustainability criteria. As he puts it: “Brands sometimes find they need less moisture barrier than they might have assumed was the case.”

A similar perspective can be applied to more traditional films, such as Innovia’s coated bi-oriented polypropylene (BOPP) range. One recently introduced product provides improved gas breathability, says Sweetman. “Higher and higher levels of barrier are not always going to be required. Going for gas and moisture permeability can be the right route to take in some cases.”

Of course, high barrier will be exactly what is required in other applications. Coating options at Innovia include polyvinyl dichloride (PVDC) for gas and moisture barrier and Sweetman says the firm is working on new options with potentially improved characteristics.

When it comes to active films, antioxidants are probably less controversial than antimicrobial agents, taking a different route to food quality and safety. John Solomon, global manager for the food market at US desiccant and antioxidant supplier Multisorb, says: “With many foods, the biggest problem influencing shelf-life is the oxidation or degradation of fats and oils.” In 95% of cases, Multisorb’s antioxidants are iron-based, he confirms, since this is usually the most economical and stable agent.

The antioxidants, which can be supplied as sachets, labels or cards, are widely used in case-ready and cured meats, baked goods, snackfoods and nuts. Solomon explains: “The shelf-life for conventionally packaged soft cookies is typically a week to 10 days. We have an application in organic cookies where that has risen to four months.” He confesses this jump is only partly attributable to the antioxidant. Barrier film was also used and an additional moisture-regulating ingredient went into the cookie.

Antioxidants can also mitigate aesthetic deterioration. With sliced ham, says Solomon, shelf-life will normally be up to 12 days. Beyond that period, the meat will start to change colour. But when an oxygen scavenger is included in the pack, the ham will stay pink and taste fresh for up to 58 days, says Solomon.

Integrating antioxidant agents into flexibles is a particular challenge, not least because of the difficulty in creating sufficient oxygen-absorbing capacity. Solomon says: “I suspect someone will manage it either late in 2008 or early in 2009.”

As Wrap points out, it remains to be proved whether longer shelf-life does actually mean less food waste. But if, as many assume, it does, then these flexible film developments will prove to be especially valuable.

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MICROBE MANAGEMENT

Much of the more interesting – and promising – research into antimicrobials has used plant and herb extracts as the active agent in flexible films.

In one case, analytical chemistry professor Cristina Nerin at Zaragoza University, Spain, worked with a preservative-free, complex bakery product with a shelf-life of just three days. Her team repackaged it in a new film with cinnamon extract as the antimicrobial agent. Microbiological as well as sensorial analysis established a shelf-life inside the new pack of 11 days. Nerin says commercialised examples of films integrating both antioxidants and antimicrobials have been on the market in Spain since August 2005.

Nerin says one key benefit of these types of natural extract and essential oil (or constituent) is that they are categorised as flavourings by the EU and Generally Recognised as Safe (GRAS) by the US Food and Drug Administration.

Wrap project manager Andrew Parry says his team has discussed projects based on antimicrobials with the Campden & Chorleywood Food Research Association (CCFRA). But he says: “One of the things that has stopped us investing in antimicrobials in the past is the uncertainty about regulations and labelling issues.”

With some agents, there are potential problems with taint and off-flavour, he adds.

Multisorb’s food market global manager John Solomon says: “There’s a lot of research going on with antimicrobials in the US, but no packaging suppliers have stood up to produce them. We’ve looked at the technologies, but any supplier would be setting themselves up for lawsuits for years to come.”