Packaging protects food from external environmental influences such as bacteria, dust or moisture, but so-called passive packaging has limited functionality.
Active packaging provides additional protection and ensures that food quality is maintained under more favourable conditions, thus preventing rapid deterioration and pathogen growth, resulting in a longer shelf life for packaged food.
1) What is active packaging and what is the "essence" of its use?
Active packaging is characterised by the fact that it contains active ingredients and thus consciously improves the environmental conditions surrounding the packaged food.
Active packaging contains components that can extract certain substances from the food (e.g. by removing oxygen from the air inside the packaging) or release desired substances (e.g. preservatives), but they can also control the humidity of the food packaging or stop pathogens from multiplying.
Active packaging can thus contribute to reducing or eliminating the use of additives (e.g. preservatives).
2.) What products are used for packaging?
Specific applications for active packaging are the following products e.g.:
- cold cuts, meat products, ready meals
- fruit and vegetables
- medicines, dietary supplements
2) How does active packaging increase the shelf life of food?
To improve food quality, active packaging contains special "active" components that are integrated into the packaging - or added as a separate insert.
As a result, different mechanisms of action and different active systems can be combined.
Active packaging:
- regulates moisture content,
- binds oxygen;
- prevents changes caused by light,
- stops the ripening process,
- protects against loss of flavour,
- reduces the growth of bacteria and pathogens.
The authorisation of active packaging is regulated by an EU regulation.
The types of active packaging are:
2.1. Humidity control
By using moisture control materials such as silica gel or starch polymers, active packaging keeps food dry in the package.
Moisture control components are either in the packaging material itself or are placed under/next to the product in inserts such as small bags or similar.
A common example of its use is the use of an absorbent tray for meat products packed under fresh modified atmosphere. Polyacrylates (plastics) absorb the meat juices that leak out over time and can hold up to 500 times their own weight. However, if the juice accumulates in such active packaging, it indicates that the capacity of the absorbent liner has been exhausted and there is an increased risk of the growth of corrosive organisms.
Absorbent coasters are also often used as coasters for plastic bowls of berries.
2.2. Oxygen sequestration
Oxygen causes the oxidation of food and accelerates the growth of aerobic (oxygen-loving) microorganisms. This in turn leads to food spoilage. Lower oxygen concentrations in food packaging can delay these processes.
Oxygen scavengers, such as iron, can actively reduce oxygen levels in food packaging. Depending on the type of material, they can be used as a separate layer in packaging materials such as foils, menu trays or PET bottles, or as a sealing insert in beverage cups.
For example, active films bind oxygen in shrink-wrapped meat products, making them more durable. Foods such as mashed potatoes or sauerkraut retain their colour longer on a tray with an oxygen-absorbing layer. Packaging materials with these properties are already being used for beers in PET bottles.
Another form of packaging can be the placement of sachets (single-strand pillow pouches), which also serve to bind oxygen.
2.3. Whey coating instead of plastic packaging
Scientists at the Fraunhofer Institute have developed a natural alternative to whey to replace synthetic coatings. Whey accumulates in large quantities as a by-product of food production and is a largely unusable by-product.
Modified whey proteins are used to produce a coating with very good moisture and oxygen barrier properties. In addition, the proteins have natural antimicrobial properties that further improve the shelf life of the food. Carbon dioxide emissions during production are also lower than in conventional packaging.
2.4. Avoiding changes caused by light
Light exposure can lead to changes in food that active packaging can prevent or at least delay, such as
- the formation of off-flavours (e.g. the so-called "glossy flavour" in milk in transparent bottles)
- degradation of valuable ingredients (e.g. vitamins)
- fading of plant pigments
- preventing oxidation (e.g. rancidity of cooking oil in white jars)
UV protection integrated into the transparent plastic packaging reduces light transmission and thus the change in the product's properties.
Some sun protection can also be achieved by adding opaque layers or heavy printing to partially transparent packaging.
2.5. Stopping the maturing process
Active packaging also delays the ripening process of food. To this end, they inhibit the formation of the "ethylene" ripening gas, which is released during the natural ripening process of fruits and vegetables.
For exotic fruits such as bananas, it is necessary to prevent ripening during long transport periods, for example by refrigeration. To complement this, ethylene absorbers in the packaging, such as potassium permanganate or activated carbon, bind ethylene and thus interrupt the ripening process during transport, often integrated into the packaging (e.g. corrugated paper).
Sachets (one-dose sachets) are also used to bind ethylene.
Once in the destination country, these fruits are then re-gassed with ethylene to make them ready for consumption.
2.6. Preventing the loss of flavour
Active packaging can also protect food from the formation of off-flavours from the environment and the loss of flavours specific to the product.
However, the problem with active packaging that suppresses flavours is that under certain circumstances, slightly spoiled foods can no longer be identified by smell, as any odour other than the product type - and therefore indicative of spoilage - is also absorbed by the packaging.
As flavourings do not have to be labelled, it is not clear in which products they are already used.
6. Prevent bacteria from multiplying
Micro-organisms in or on food alter its organoleptic properties and can lead to deterioration, including gastrointestinal diseases. To prevent these processes, packaging is used to inhibit the growth of bacteria.
To control bacteria, silver compounds, organic acids or other preservatives with antimicrobial effects are used (in Japan, for example, wasabi is used for this purpose).
Skin packaging - a film shrink-wrapped around the product - also helps to keep bacteria from multiplying.
Researchers at the Fraunhofer Institute have created an antibacterial packaging coating using sorbic acid (a preservative). When the film comes into contact with food, it releases active substances onto the surface of the product.
As the ingredients of active packaging do not need to be labelled, it is not known which products already use this technology. In principle, however, only authorised substances can be used as active ingredients in food packaging.
What kind of packaging for what product? We are happy to help!
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
