What is Gas Flush?

Packaging that uses gas flush – also known as Modified Atmosphere Packaging (or MAP) – is a common packaging method used to extend the shelf life of food. It is most commonly used for fresh meat that will need to be preserved for a decent length of time – for instance for products being exported overseas.

How Does Gas Flush work?

The process of gas flush is pretty simple. Before a package is sealed off, inert gases such as carbon dioxide or nitrogen are injected into the pack. Because they are heavier than oxygen, they ‘flush’ the oxygen out of the interior of the pack, so when it is closed and sealed, only these inert gases are trapped inside the packaging and the oxygen is removed.

Why Gas Flush?

The reason gas flush is used is because oxygen can cause meat to deteriorate more quickly. It allows for the oxidative deterioration of foods and its presence is required for the growth of aerobic micro-organisms which can cause food to spoil.

In contrast, food will not react to the inert gases used in gas flush, which results in: 

• extended product shelf life
• increased product integrity
• protection against discoloration

For some products, the injection of these gases also creates a cushion-like puffer, by puffing up the packaging, helping to protect more fragile products like dry potato chips.

What Gases are Used?

There are several gases commonly used for gas flush packaging, each of which have different properties. The correct mix of gases varies depending on the product being packaged, and it is best to speak to your packaging supplier to find what works best for you.

Different Types of Gases Available

Carbon Dioxide:

This gas inhibits the growth of most aerobic bacteria and moulds, and so theoretically the higher the percentage of this in a pack, the longer the shelf life. However, CO2 is easily absorbed by most foods, so having too much can cause flavour tainting or pack collapse.

Nitrogen:

Nitrogen is an inert gas basically used a filler in a gas flush mix – often combined with carbon dioxide to prevent pack collapse. It is heavy, and so will push oxygen out of your pack, and will not react with the food in any way.