What is Modified Atmosphere Packaging?

Modified Atmosphere Packaging (MAP) is a food preservation technique that replaces the air inside a package with a carefully controlled mixture of gases to extend shelf life and maintain product quality. It slows spoilage by creating an environment that inhibits microbial growth and oxidation.

In this guide, we’ll explore:

• How MAP works
• Its key benefits
• Main applications across industries

How Modified Atmosphere Packaging Works

Modified Atmosphere Packaging works by altering the composition of gases surrounding a food product.

The standard air we breathe contains approximately 78% nitrogen, 21% oxygen, and small amounts of other gases including carbon dioxide. In MAP systems, this natural air composition is replaced with a specific gas mixture tailored to the particular food being packaged.

The most commonly used gases in MAP are nitrogen, carbon dioxide, and oxygen in varying proportions. Each gas serves a distinct purpose in food preservation:

• Nitrogen – acts as an inert filler gas that displaces oxygen, preventing oxidation and inhibiting the growth of aerobic microorganisms. It also helps maintain package shape and prevents collapse.
• Carbon dioxide – particularly effective at inhibiting bacterial and mold growth. When dissolved in the food’s moisture, it forms carbonic acid, which creates an environment hostile to many microorganisms.
• Oxygen – typically reduced in MAP applications, though it’s sometimes included in specific concentrations for certain products like fresh red meat to help maintain the desirable bright red color.

The packaging materials used must provide an effective barrier against gas transfer to maintain the modified atmosphere throughout the product’s shelf life.

Key Benefits of Modified Atmosphere Packaging

Extended Shelf Life

The most notable benefit of MAP is its ability to dramatically extend the shelf life of perishable products. By creating an environment that slows microbial growth and oxidative reactions, MAP can increase shelf life by two to five times compared to conventional packaging.

For example, fresh meat products that might last only a few days under normal conditions can remain fresh for up to 12 days depending on the specific product and conditions. Similarly, bakery items that would typically go stale or develop mold within days can stay fresh for weeks or even months.

This extended shelf life reduces food waste significantly, addressing a major global sustainability challenge.

Reduced Need for Preservatives

MAP offers a natural way to preserve foods with minimal or no chemical preservatives.

This supports the growing consumer demand for clean-label products with fewer additives. By using gases that naturally occur in our atmosphere, food manufacturers can maintain product freshness without relying on synthetic preservatives.

For many products, MAP can reduce or eliminate the need for preservatives like sulfites, benzoates, and sorbates.

Maintained Product Quality

Unlike some preservation methods that may alter taste, texture, or appearance, MAP helps maintain the original sensory qualities of food products.

Fresh produce retains its crisp texture and vibrant color. Meat products maintain their appetizing appearance and flavor profiles. Baked goods stay soft and fresh without becoming soggy or stale.

MAP preserves not just the safety of food but also its sensory appeal, creating a better experience for the end consumer.

Expanded Market Reach

With longer shelf life comes greater distribution potential. Products can travel farther and remain on shelves longer, opening new market opportunities for food manufacturers and distributors.

This expanded reach benefits both producers and consumers, increasing access to diverse food options regardless of geographic location.

MAP Applications in Different Industries

Fresh Meat, Poultry and Seafood

The meat industry was among the earliest adopters of MAP technology, and for good reason. Fresh meat is highly perishable and particularly susceptible to both microbial spoilage and color changes.

For red meats, MAP typically uses a high-oxygen environment (70-80% oxygen, 20-30% carbon dioxide) to maintain the bright red color consumers associate with freshness while inhibiting bacterial growth.

Poultry products benefit from a different gas mixture, usually with higher carbon dioxide levels (25-30%) and lower or no oxygen, which inhibits spoilage bacteria without affecting the product’s appearance.

MAP has revolutionized distribution capabilities for seafood as a highly perishable category. Fish and shellfish typically require very high carbon dioxide levels (40-60%) to effectively control bacterial growth.

With proper MAP, fresh seafood shelf life can be extended from 2-3 days to 5-7 days or more, allowing for wider distribution of these valuable proteins.

Fresh Produce

Fruits and vegetables pose unique challenges for MAP  because they continue to respire after harvesting, meaning they consume oxygen and release carbon dioxide.

To account for this, MAP often uses films with specific permeability characteristics to create an equilibrium modified atmosphere.

Different produce items require different gas compositions. For examples:

• Leafy greens – very low oxygen levels (1-5%) and moderate carbon dioxide (5-15%) to slow respiration and prevent browning.
• Berries and other soft fruits – carbon dioxide levels (up to 15%) to inhibit mold growth while staying within tolerance limits.
• Root vegetables and apples – even higher carbon dioxide environments (sometimes exceeding 20%) to inhibit sprouting and maintain firmness.

Bakery Products

Bakery goods face two primary spoilage mechanisms – mold growth and staling. MAP addresses both challenges effectively.

Most bakery MAP applications use nitrogen as the primary gas, sometimes with small amounts of carbon dioxide. This combination displaces oxygen to prevent mold growth while maintaining product texture.

Cakes, breads, and pastries packaged with MAP can achieve shelf life extensions from days to weeks or even months, depending on the specific product and packaging system.

The absence of preservatives in MAP bakery products appeals strongly to consumers looking for cleaner labels without sacrificing convenience or shelf life.

Ready-to-Eat Foods and Prepared Meals

The growing market for convenience foods has been significantly enhanced by MAP technology. Ready-to-eat meals, sandwiches, and prepared salads all benefit from the shelf life extension MAP provides.

Customized gas mixtures are typically required for these complex food systems containing multiple ingredients,  Most use some combination of nitrogen and carbon dioxide, with oxygen levels kept very low.

MAP has been crucial to the expansion of the fresh, refrigerated ready-meal category, allowing for weekly rather than daily production and distribution cycles.

The Technology Behind MAP Systems

The equipment used for modified atmosphere packaging ranges from simple tabletop machines for small operations to sophisticated, high-speed automated systems for large manufacturers.

Gas flushing systems work by flowing the desired gas mixture through the package prior to sealing, displacing the ambient air. This method is fast but may leave residual oxygen levels of 2-5%.

Vacuum compensation systems first remove all air from the package then introduce the gas mixture before sealing. This achieves lower residual oxygen levels (typically below 1%) but operates at slower speeds.

The packaging materials themselves are critical components of effective MAP systems. Films must provide appropriate barrier properties against gas migration while meeting other requirements for product visibility, physical protection, and machinability.

Many MAP applications use multi-layer films combining different materials to achieve the optimal balance of properties. Common materials include:

• Polyethylene
• Polypropylene
• Ethylene vinyl alcohol (EVOH)

Key Considerations for Implementing MAP

Proper gas mixtures must be carefully determined based on the specific product characteristics to ensure effective MAP. Key factors to consider include:

• pH values
• Water activity
• Fat content
• Natural microflora

Even if you use MAP to preserve foods, temperature control is still important. While MAP extends shelf life significantly, it works best when combined with proper refrigeration. 

Initial product quality also influences MAP effectiveness. The technology can preserve quality but cannot improve a product that was already compromised before packaging.

Cost considerations include not just the gases and packaging materials but also equipment investment, training, and potential changes to production flow and logistics.

Leverage MAP To Keep Foods Fresh

Modified Atmosphere Packaging is a major advancement in food preservation technology, offering extended shelf life and maintained quality without chemical preservatives.

As consumer demand for fresh, minimally processed foods continues to grow, MAP provides a valuable solution for producers, distributors, and retailers alike. By understanding the principles and applications of this technology, food industry professionals can leverage MAP to meet market demands while reducing waste and expanding their reach.