Active packaging

The way in which active and smart packaging can secure the quality and freshness of products is a highly topical issue for both the food processing and packaging industries. Active packaging systems are designed to safeguard food quality. Over the coming years we will see moves towards the broad-based market introduction of active and smart packaging. Smart packaging materials monitor the state of packaged products permanently providing information on their freshness. New systems accelerate and optimise the preparation of meals.

Today, product managers in the food industry are faced with the question of whether the active and smart systems currently available on the market offer advantages for the respective merchandise packaged and which of these systems offer the greatest benefits. Despite applying the very latest developments in the quality protection of packaged products during distribution, logistics and storage factors can occur that impair the quality. These include:

• Light-induced spoilage - for instance, the taste of light (milk), oxidation in beer, browning/colour changes in juices and rancidness in products containing fat;
• Enzymatic/oxidative perishing of products with a longer shelf life. This includes rancidity, aroma and colour changes in dry and frozen products, to name but a few;
• Microbiological spoilage of fresh products, which typically takes the form of mould on fresh vegetables, among other things.

Active and smart packaging developments worldwide focus on a number of functions:

• Binding residual oxygen existing in the headroom inside packaging;
• Catching dripping water and controlling the humidity in the headroom inside packaging;
• Absorbing ethylene in order to slow down fruit ripening;
• Introducing anti-microbial agents;
• Absorbing odours;
• Filtering out determined wavelengths of light that damage the packaged goods;
• Displaying ambient conditions such as temperature and gas concentration inside the packaging; and
• Detecting detrimental microorganisms inside the packaging.

So far, three viable solutions have crystallised as marketable technical solutions for oxygen scavengers. Either additional sachets containing an oxygen absorber are introduced or respective labels are attached to the inside. Finally, there is also the possibility of incorporating the technology into the packaging material itself.

Even now, indicator systems in the shape of labels are stuck on/into the packaging. Their change in colour indicates that inside the packaging microbes have already reached substantial, and therefore probably critical, numbers. The current trend now is to incorporate such systems into the packaging material.

In contrast to indicator systems these so-called Smart Active Labels make it possible to permanently track ambient parameters such as time, temperature, gas concentrations etc, thereby ensuring the precise monitoring of the food.

Consumers want to know whether the cold chain of a product has been interrupted. Here the use of thermochromic printing inks makes sense. These are water-repellent inks that visually display whether goods have been stored in line with the recommended best-before shelving instructions. Once the colour has changed it will not return to the original shade. Such properties give consumers the assurance that products are suitable for consumption.

A Danish company has developed packaging that actively assists in the preparation of convenience dishes in the microwave. This active packaging ensures optimum temperatures for microwave cooking. The flexible bag is placed directly in the microwave. A proprietary valve system ensures the desired temperature and optimum vapour pressure is achieved, thereby protecting the film from bursting and retaining the aroma of the ingredients and seasonings. The valve is produced in the manufacturing process of the film by selective perforation of one film layer, ie, in the bag forming and filling process no extra applications for valves are required. The two-layer film with its built-in valve system can be used without changing the packaging or sealing processes. Before cooking the valve is closed safely so that neither freezer burn nor hoar frost can form on the product.

Another version is a metallic composite film lining that reflects microwaves allowing consumers to produce perfectly prepared food. Foodstuffs like spring rolls or pizza become crunchy. The packaging is cut open at both ends before it is put into the microwave. The proprietary film ensures controlled heating and prevents the film from burning. The operation principle works as follows: the metal-coated inside of the packaging absorbs the microwaves and converts them into the heat required for frying and baking.

In the development of new packaging, manufacturers closely cooperate with food producers. Their newly developed active packaging in turn inspires food producers to come up with new product series.

An American supplier, for instance, has developed a new oxygen scavenger to improve freshness retention and the quality of packaged foodstuffs - a so-called special 'outgredient'. This means the oxygen absorber is no longer added to the food as an ingredient. Using this outgredient, packaged products such as cold cuts, meat and sausages, nuts, bakery produce, snacks and dairy products can be kept fresh longer without impairing their taste or colour properties. This development protects the food from decomposition, mould formation and other degradation processes. According to the manufacturer's information this renders the use of additional preservatives partly or completely superfluous.

The product there is a self-adhesive oxygen absorber that can be individually cut to size and then subsequently coiled so that it is also suitable for pressure-sensitive labels.

It can be attached to the inside surface of nearly all types of packaging using oxygen barrier technology to bring down the oxygen content inside the packaging to a level of below 0.01%.