The Leak Issue in MAP is Important for Your Product´s Shelf Life

In Modified Atmosphere Packaging (MAP) leaks are bad news. Now, new research has shown just how damaging even the tiniest leak can be. In a package where most of the oxygen has been flushed out, even a miniscule hole, half the diameter of a human hair, can allow oxygen from the air to enter the package remarkably quickly. After less than three days oxygen levels can be high enough to allow bugs such as bacteria and mould to grow, making a nonsense of the use-by date and risking the reputation of the brand.

The issue of leaks is crucial to MAP, but there is little solid information about just how quickly air can get into a package that has a leak. To answer this question technical experts at the Denmark-based company Dansensor carried out a series of tests.


Small leak, big problem

The experts, led by Electronics Engineer Rune B. Abrahamsen, took a package and flushed out the air until only 0.1% oxygen remained inside. They then made holes of different sizes in the packaging film and measured how long it took for oxygen from the surrounding air to enter the package.

The graph shows how quickly gas enters the package depending on the size of the hole.

  • If there is a hole that is only 50 microns in diameter – that is around half the diameter of a human hair – it takes about 70 hours for the oxygen levels in the package to reach 10 per cent.
  • At these levels of oxygen, microbes such as mould and bacteria can start to grow.
  • And often 70 hours is the sort of time it takes to get the product from the factory to the supermarket shelf.
  • In other words, even with a tiny leak the shelf life of the product will almost certainly be significantly reduced.
  • If the leak is 100 microns – one-tenth of a millimetre – the Dansensor team found that the oxygen levels in the package will be close to the same level as air in less than one week.

Leaks mean reduced shelf life

If a leaking package ends up on the supermarket shelf this could have serious consequences in terms of:

  • Reduced shelf life – possibly from months to weeks or even days
  • Poor customer satisfaction
  • Recall of products
  • Damage to the brand

Sealing is crucial for MAP

“The surprising thing is that many companies do not know how oxygen affects the shelf life of the product” says Joel Fischer, manager of the Minnesota Laboratory of MOCON Inc., Dansensor’s parent company. “It is important that people do understand what is happening and that they carry out appropriate research and testing on their packaging.”

Joel Fischer
As packaging materials evolve, the issue of leaks is becoming more important. “People are changing their approach to packaging materials in response to consumer demand” says Joel.

“The trend is to move away from traditional materials such as glass and cans, which can be sealed easily, towards much more versatile and flexible packaging.” This includes such things as trays with lids or flexible foil pouches.

Products in this type of packaging are often placed in a modified atmosphere to extend the shelf life. MAP works by flushing air from the package and replacing it with another gas or mixture of gases.

In most cases the idea is to replace the oxygen that is in air, as this encourages the growth of bugs such as mould and bacteria. These cause spoilage of the product. Food processors typically replace the oxygen with gases such as nitrogen and carbon dioxide. These slow down the growth of organisms that can spoil food.

Leaks in MAP packaging can arise from various sources and can be difficult to spot by eye. Typically a leak can appear if particles of the product become stuck in the seal. Or the packaging machine may not be sealing correctly. Sometimes the handling of the package can cause a leak.

“These problems could result in significant costs to the company. So it is vital that appropriate tests are carried out on packages before they leave the production facility to ensure that they are leak-free,” Joel adds.


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