Is the Gas Composition in my Modified Atmosphere Packaging Product Correct?

Headspace test

Headspace test

To believe is good, but to know is absolutely better - this is also true of modified atmosphere packaging (MAP). Basically there are two methods: Random testing and on-line monitoring. The instruments used are gas analysers which measure oxygen (O2) or oxygen/carbon dioxide (O2/CO2), depending on which blend is used in the packages.

Random Testing
In connection with modified atmosphere packaging, the basic test method is random testing, also called spot testing: Within certain time intervals - typically 20 or 30 minutes - people from the laboratory collect a number of sequential packages from the packaging machine. 5-10 packages is a good, representative sample. If you have more than one machine, samples from the different machines must be kept separate from one another and marked with some kind of identification tag. The actual test must be performed immediately after the collection, as some products will interact with the atmosphere in the package. Cheese, for instance, absorbs CO2, and in bread packages oxygen will often diffuse into the package headspace. To ensure maximum consistency in your testing, the test conditions should always be the same. A gas sample from the package headspace is introduced into a gas analyser - the headspace analyser - by way of a syringe (needle). When the needle is introduced into the package, the gas sample is automatically pumped into the analyser and the reading is instantly displayed. The needle should be introduced into the package through a septum - a kind of rubber sticker - which prevents atmospheric air from entering the package through the needle hole.

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On-line quality control
On-line analysis of the gas composition in connection with MAP means that each package is measured non-destructively before sealing, as the analyser continuously samples near the sealing area. If the gas composition is incorrect, alarms will be activated so that the operator can stop the machine immediately. On gas packaging flow wrapping machines (both VFFS and HFFS) the gas sample is led to the analyser through a thin teflon tube placed near the sealing area or before the gas lance ends. (The position depends on the machine type.)

Some machine manufacturers supply combined lances for both gas supply and measuring. When using gas analysers for flow packaging machines, the response time is close to real time and will therefore give a true picture of the gas composition.