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Modified Atmosphere Packaging: The science of keeping things fresh

fresh pizza
Fresh, safe, and preservative-free food is in demand now more than ever. Bread that stays fresh for days on the shelf, wafers that stay crisp for months in the packet, even fruits and vegetables. Until recently the only option to extend the shelf-life of a packaged product was with the use of synthetic additives and/or low temperatures. The arrival of compressed gas and nitrogen changed the game. MAP (Modified Atmosphere Packaging) is the mechanism that leverages these two utilities to lock in a product’s freshness and extend its shelf-life.

What it involves

Modified Atmosphere Packaging aims to achieve exactly what its label says: modify the atmosphere within the packaging, in order to limit oxidation and microbial growth. The three main gases involved in MAP are nitrogen, oxygen, and carbon dioxide— either on their own or in combination.

MAP can be of two kinds: active or passive. Active MAP sets about modifying the atmosphere by flushing in a controlled mix of gases into the package right before it is sealed. This can be done in either two stages or one. The two-stage approach involves first removing the existing air from inside the package (with the help of a vacuum system) before flushing in the gas mix. The single-stage method goes straight ahead with flushing in the gas. 

Passive Modified Atmosphere Packaging (used largely for fruits and vegetables) leaves it to the products to develop the desired atmosphere through respiration. Here special packaging film is used to help the products breathe. 

The technology

Depending on the product and the required production volume, various types of packaging machines are used for MAP. The most common types of machines used are:

Form-fill-seal machines: Used in larger operations, these machines place the product into a suitable pouch and flush in the modified atmosphere before sealing the pouch.

Chamber machines: Used in smaller operations, these machines fill the wrap with the product, vacuum pulls the atmosphere within, then flush in the modified atmosphere, before heat-sealing. 

To make the most of MAP, these machines depend on high-quality equipment such as:

  • Vacuum pumps: They remove oxygen from the packaging, thereby extending the product’s shelf life.
  • Nitrogen generators:  After oxygen is removed, the packaging is filled with nitrogen and other gases to inhibit aerobic spoilage.

Foods that benefit from MAP

• Dried snacks • Pasta, breads • Wine, juices, coffee, tea • Dairy Products • Meat products • Seafood products • Ready meals / chilled meals • Fruits and vegetables

Other technologies that are indispensable in Modified Atmosphere Packaging include gas mixers and metering systems, and gas analyzers. These are responsible for creating the necessary mixture of gases, continuously analyzing the same, and ensuring the safety, purity, and quality of the mix. 

The benefits of MAP

  • Extends shelf life without use of synthetic food additives
  • Preserves freshness, appearance, aroma, flavor, nutritional profile
  • Restricts food decay during distribution, expands distribution territories
  • Reduces supply chain waste
  •  Longer / more efficient product runs

PSA Nitrogen Generators

Pressure swing adsorption (PSA) generators allow companies to produce their own nitrogen instead of relying on third-party vendors. This offers wide-ranging benefits, such as lower costs, reduced logistics, and increased flexibility (for more on the many benefits of on-site nitrogen generation, go here). These generators are a very safe nitrogen solution and quickly pay for themselves.