Choosing the best materials is key therefore Modified Atmosphere Packaging (MAP) relies on science to ensure the ideal rate of respiration and transpiration, and the correct combination of gases, to delay product decay, significantly extend shelf life, and reduce waste. But it also needs the correct packaging materials.
Because the atmospheric conditions inside the packaging material depend on its permeability, packaging films are chosen depending on the individual needs and characteristics of the different food products. Red meat, for example, needs high oxygen to maintain its red colour, while bread requires low oxygen to avoid mould.
Fruit and vegetables need a very specific amount of oxygen in the headspace in order to maintain their just-picked quality, so the material used for packing these products needs to be quite permeable to oxygen so that oxygen in the atmosphere can replenish the gas in the packaging.
The transparency of the packaging material is also important, as this determines how much light reaches the produce, as well how visible it is to the consumer.
Other important criteria, such as sealing characteristics and water vapour transmission rates, are measured and tested at different stages of the packaging process as the chosen film’s performance may vary along the way.
All MAP materials must have the mechanical strength to stand up to machine handling, storage and distribution, but they must also be cost effective, look appealing for consumers, and be able to be effectively and visibly branded. This is why plastic is the overwhelmingly popular choice. In fact, flexible plastic packing materials make up 90% of all MAP. Foil, metal, glass, paper and cardboard account for the remaining 10%.
Plastic’s popularity is due largely to its integral strength, as well as the huge range of differing permeabilities.
Types of Plastic Used for MAP
This is a popular choice as it seals well through a degree of contamination and has good anti-fogging and peel ability characteristics. There are three main types of polyethene:
- Low density – Makes up the biggest proportion of all plastic packaging materials. This inert film has the low permeability for water vapour, but a high permeability for gases.
- Linear low density – known for its superior resistance to tearing and high impact strength, this material also has good puncture and environmental stress cracking resistance.
- High Density – This material has poor clarity, but offers a higher softening point than linear low-density polyethene and superior barrier properties.
- Regular polypropylene – chemically similar to polyethene, but can be extruded or co-extruded.
- Oriented polypropylene – has a gas and moisture barrier up to 10 times that of polyethene. It also has excellent resistance to oil and fat.
- Co-extruded Oriented Polypropylene (COPP) – this is used mainly as breathable packaging for fresh produce as it is the only commercially available film where gas flow in the MAP is required.
Mapflex is a joint venture between international companies and is a recognised specialist in PerfoTec packaging. We ensure the right films and packaging methods and best materials are used to maximise the benefits of equilibrium modified atmosphere (EMA). Contact us for tailored packaging solutions and modified atmosphere packaging products specifically suited to your fresh produce needs.