What is Modified Atmosphere Packaging?

A major challenge food manufacturing industries face is the need to keep their products as fresh as possible for as long as possible. Modified atmosphere packaging (MAP) addresses this concern by changing the composition of gases surrounding food within its packaging to help preserve freshness and extend shelf life.

As consumers raise their demands for foods that last longer, the need for effective food preservation methods has become increasingly important. This article will discuss the concept of modified atmosphere packaging and its relevance to the food processing industry.

What Is Modified Atmosphere Packaging (MAP)?

The USDA describes modified atmosphere packaging as a technique that changes the gas composition surrounding a product to help extend shelf life and reduce deterioration. Nitrogen, carbon dioxide, and oxygen are used individually or in combinations suited to the food being packaged.

The intention is to preserve the freshness and quality of the contained food for as long as possible. Depending on the product, the packaging atmosphere may be selected to slow oxidation, limit the growth of certain spoilage organisms, or maintain the appearance of the food.

Modified Atmosphere Packaging vs. Controlled Atmosphere Packaging

While modified atmosphere packaging and controlled atmosphere packaging share many similarities, there is an important difference in how the atmosphere is maintained.

Modified atmosphere packaging establishes a desired atmosphere within the package, but the gas composition may change during storage. These changes can result from food respiration, interactions between the food and gases, or the movement of gases through the packaging material.

On the other hand, controlled atmosphere systems monitor and maintain the gas composition throughout storage. This approach is commonly associated with larger storage environments where gas levels can be measured and adjusted.

Regardless of the procedure being used, packaging integrity and environmental storage conditions must be fine-tuned to achieve the best results.

Modified Atmosphere Packaging vs. Vacuum Packaging

Vacuum packaging removes air from a package before sealing it, leaving reduced pressure inside. Active modified atmosphere packaging introduces a selected gas or gas mixture to establish the desired environment around the food.

The choice depends on the product and its storage requirements. For example, gas-filled packaging can provide space around fragile foods, while vacuum packaging draws the packaging material closely against its contents.

How Does Modified Atmosphere Packaging Work?

Modified atmosphere packaging can be achieved by active and passive methods.

Active modified atmosphere packaging involves the introduction of a desired gaseous mix into the packaging environment to achieve a longer shelf life. Gas flushing is a common example, in which a selected gas displaces the air within the package before sealing.

Conversely, passive modified atmosphere packaging relies on the interaction between the food and the packaging material. Fresh produce continues to respire after harvesting, consuming oxygen and releasing carbon dioxide. Films with suitable gas permeability allow an atmosphere to develop that helps preserve the product.

Both approaches require packaging materials suited to the food being preserved. Film properties, seal integrity, and storage temperature affect how well the desired atmosphere is maintained.

Common Modified Atmosphere Packaging Gases

The most common gases for modified atmosphere packaging are nitrogen, carbon dioxide, and oxygen. Each gas serves a different purpose, and the appropriate mixture depends on the product and its primary causes of deterioration.

Nitrogen

Nitrogen is commonly used to displace oxygen and slow oxidative processes that affect food quality. Due to its low reactivity, nitrogen can help preserve flavors without reacting readily with the packaged food.

Nitrogen also serves as a filling gas, helping maintain package volume and providing cushioning around fragile products. Learn more about the use of nitrogen in food packaging.

Carbon Dioxide

Carbon dioxide helps inhibit the growth of certain spoilage bacteria and molds. It is frequently combined with nitrogen or oxygen to create an atmosphere suited to a particular food.

However, carbon dioxide can dissolve into food, potentially affecting product quality or causing the package to collapse. The appropriate concentration must therefore be selected for the application.

Oxygen

Although many MAP applications reduce oxygen levels, some foods benefit from its presence. Oxygen may be included to maintain the red appearance of certain fresh meats or support the respiration of fresh produce.

The objective is to establish an atmosphere suited to the food rather than remove oxygen from every package. Other gases, such as argon, may be used in specialized applications.

What Foods Use Modified Atmosphere Packaging?

Modified atmosphere packaging is used for a wide variety of food products. Common applications include:

• Snack foods and nuts: Nitrogen helps reduce oxidation in products containing fats and oils. Gas-filled packaging can also help protect fragile snacks during handling.
• Coffee: Nitrogen flushing can help limit oxygen exposure, while one-way valves allow gases released by roasted coffee to escape.
• Meat and poultry: Product-specific gas mixtures help manage spoilage and maintain the desired appearance.
• Cheese and bakery products: Suitable atmospheres can help slow the growth of certain spoilage organisms.
• Fresh fruits and vegetables: Films with appropriate gas transmission properties help balance product respiration and gas exchange.

The appropriate gas mixture and packaging material will vary between products. A method suited to dry snack foods may not be suitable for fresh produce or refrigerated meat.

For additional applications, explore the role of nitrogen in food processing and packaging.

Modified Atmosphere Packaging Methods and Materials

The most useful methods and materials for modified atmosphere packaging are outlined below.

Barrier Films and Gas-Permeable Films

Packaging films help control the movement of gases and moisture between the food and its surroundings. Barrier films limit gas exchange, helping retain an atmosphere introduced during packaging.

For fresh produce, films with suitable permeability or perforations allow gas exchange to support the desired atmosphere. The material must be selected according to the product’s respiration rate, moisture requirements, and storage conditions.

Food-contact suitability, sealing properties, and resistance to damage are also important considerations. Additionally, some packaging systems include indicators that provide information about storage conditions or package integrity.

Oxygen Scavengers and Desiccant Packs

Oxygen scavengers and desiccant packs serve different purposes within food packaging.

Oxygen scavengers absorb residual oxygen, helping limit oxidative deterioration. Desiccant packs absorb moisture and may be useful for foods that require a dry packaging environment.

These components must be selected for the specific food application. They may support a packaging system, but they do not replace appropriate gas selection, sealing, or storage practices.

One-Way Packaging Valves

Another modified atmosphere packaging technique involves the addition of one-way valves to product packaging. These valves allow gases to move out of the package while limiting the entry of outside air.

This method is particularly useful for products such as roasted coffee, which continues to release carbon dioxide after packaging. Allowing the gas to escape helps prevent pressure buildup within the package.

Gas Flushing

For food and beverage processing plants involved in large-scale operations, gas flushing is a common active modified atmosphere packaging technique. The process introduces a selected gas or gas mixture to displace air before the package is sealed.

Due to its low reactivity, nitrogen is widely used in gas flushing. It can serve as the primary packaging gas or form part of a mixture with carbon dioxide or oxygen.

Using nitrogen helps reduce oxygen exposure and slow oxidative processes that affect food quality. However, nitrogen does not sterilize food or prevent the growth of all microorganisms. Packaging conditions must be selected and validated for the product.

Advantages of Modified Atmosphere Packaging

The benefits of modified atmosphere packaging for the storage and transport of food products can include:

• Prolonged shelf life compared to packaging in ordinary air
• Improvement in the visual appeal of packaged products
• Preservation of food freshness and quality
• Retention of food flavors
• Reduced product waste caused by premature spoilage
• Potentially reduced reliance on certain preservatives

The extent of these benefits depends on the food, gas mixture, packaging material, and storage conditions.

Limitations of Modified Atmosphere Packaging

While modified atmosphere packaging offers several advantages, it requires careful process control. Manufacturers must account for the cost of packaging equipment, gases, suitable films, and quality checks.

Leaks or defective seals can allow the packaging atmosphere to change, reducing its effectiveness. Gas composition and seal integrity should therefore be checked as part of the packaging process.

MAP also does not replace refrigeration where it is required. Low-oxygen environments may favor the growth of some harmful microorganisms, making appropriate food safety controls essential. Manufacturers must validate shelf life under the intended storage and distribution conditions rather than assume a standard extension applies to every product.

Is Nitrogen Flushing Bad for You?

Food-grade nitrogen is used in food packaging when it meets applicable quality requirements and is applied under appropriate manufacturing conditions.

However, nitrogen flushing does not make food safe regardless of how it is processed or stored. Product safety still depends on sanitation, packaging integrity, temperature control where required, and a validated shelf life. Consumers should follow the storage instructions and use-by dates provided on the package.

Nitrogen Supply for Modified Atmosphere Packaging

Food manufacturers can obtain nitrogen through delivered cylinders, bulk supply, or on-site nitrogen generation. Comparing nitrogen supply options involves evaluating gas consumption, production schedules, facility requirements, and operating costs.

On-site nitrogen generators separate nitrogen from compressed air, providing a supply at the facility. These systems use PSA or membrane nitrogen generation technology. For operations with ongoing nitrogen demand, this can reduce reliance on scheduled deliveries.

When selecting a nitrogen system for MAP, manufacturers should consider:

• Required nitrogen flow during normal operation and peak production
• Gas pressure at the packaging equipment
• Applicable food-grade nitrogen requirements
• The residual oxygen target within the finished package
• Gas monitoring and integration with the packaging line

The industrial air compressor supplying the system must also meet the generator’s inlet requirements. Selecting the right air compressor for a nitrogen generator requires consideration of feed air flow, pressure, and air treatment needs at the required nitrogen output and purity.

Nitrogen purity and residual oxygen within a finished package are related but different measurements. Flushing effectiveness, package design, and seal quality also influence the final packaging atmosphere.

An on-site nitrogen generator supplies the nitrogen component of the process. Applications requiring carbon dioxide or oxygen will need suitable additional gas supplies and mixing equipment.

NiGen Has Industrial Air Solutions

At NiGen, we offer a broad range of turnkey industrial air solutions to the clients we serve. Our process air equipment supply and installation services are designed for a diverse range of manufacturing industries and include on-site nitrogen generators for operations requiring a dependable nitrogen supply.

For food packaging applications, our team can help evaluate nitrogen generation options based on your required flow, pressure, and purity.

For temporary nitrogen supply needs, ask our team about nitrogen generator rentals and equipment options suited to your required flow, pressure, and purity.

Contact us online today for a quote or to discuss your packaging nitrogen requirements.