MAP and film packaging explained
Modified Atmosphere Packaging (MAP) is an increasingly popular method of preserving food products and increasing their shelf life. It is an alternative to traditional sealed packaging. Instead of sucking the air out of a container and sealing it against outside oxygen, the MAP process displaces the oxygen in the container by injecting an inert gas mixture which slows the ageing and decaying process of the product. Exposure to oxygen reduces the shelf life of food because it allows products to oxidise and undergo biochemical spoilage. It also enables the growth of aerobic bacteria, which leads to microbial spoilage. By reducing oxygen exposure, MAP sealing eliminates these problems, and prolongs shelf life. It also preserves the taste, smell and texture of food and drastically reduces product turnover.
What are MAP and film machines?
MAP fill and seal machines work by providing airtight packaging for food products, while at the same time dispensing gases to displace the oxygen from the interior of the packages. Gases such as nitrogen and CO2 are pumped into the packages, removing oxygen completely. The benefits of MAP include:
- Longer shelf life
- Better quality control
- Cost reduction
- Waste elimination
- Reduced labour
- Better manufacturing capacity
Why is nitrogen gas used in packaging food?
While carbon dioxide and argon are excellent gases to use for MAP packaging, nitrogen is still the most popular option. This is because nitrogen can be produced plentifully and cheaply, making it the most cost-effective option. Other gases, on the other hand – argon, in particular – are quite costly by comparison. Nitrogen also has a very minimal effect on the flavour of food products, while carbon dioxide can tend to affect the taste of food. Nitrogen effectively and cheaply extends the shelf life of foods.
How long does nitrogen packed food last?
Nitrogen-packing extends the life of foods significantly. The extent to which it prolongs shelf life depends on the specific food in question. Fish and seafood can last for about two days longer, while nuts and seeds can last for an additional year. In the middle of that range, the life of breads and pastries can be extended from an average of about 14 days with normal packaging, to about 12 weeks. Cheese can normally last for about four days if packed normally, while MAP packing will extend its life to 12 weeks.
How does MAP affect packaged foods?
Aside from preserving the freshness of foods, MAP can have some other effects, depending on the gases used. Preventing exposure to oxygen stops biochemical spoiling from taking place and stunts the growth of aerobic bacteria. This is what keeps the food fresh. When nitrogen is used, there seldom any adverse effects on the food. Nitrogen does not easily absorb into the product or diffuse outward through the packaging, so it maintains freshness while preserving the taste and appearance of the food. Carbon dioxide, on the other hand, is easily absorbed into the food, which can affect the flavour. It can also diffuse out of the packaging, causing it to collapse. The best way to get all the benefits of MAP without any side effects is to use nitrogen.