Modified Atmosphere Packaging (MAP) has revolutionized how we store and preserve food. By altering the atmosphere inside packaging, companies can protect products, extend shelf life, and maintain product quality. Nitrogen-based MAP is one of the most widely used forms, and it’s easy to understand why. Nitrogen, thanks to its inert properties, displaces oxygen, significantly curbing oxidation, spoilage, and microbial growth.
However, implementing a nitrogen MAP system isn’t as simple as flipping a switch. This blog will guide you through the key considerations for effectively implementing nitrogen-based MAP across food categories, from selecting the right gas mixture for modified atmosphere packaging to ensuring quality control.
Understanding Your Product: The Foundation of Nitrogen-Based MAP Success
The type of product being packaged is the single most important factor when designing an MAP strategy. Different foods have unique characteristics that influence their interaction with a nitrogen-based atmosphere.
Respiration Rate (For Fresh Produce)
Fresh produce continues to respire after harvest, meaning it consumes oxygen and releases carbon dioxide. The atmosphere inside the packaging must account for the produce’s respiration rate. For fast-respiring products (like berries), a lower oxygen and higher carbon dioxide environment is ideal.
Sensitivity to Oxygen
Oxygen is a major culprit in food spoilage through reactions like lipid oxidation and pigment degradation. Products high in fats or oils, such as nuts, snacks, and processed meats, are especially prone to oxidation. For these categories, nitrogen’s ability to displace oxygen can help maintain quality and freshness.
Potential for Microbial Growth
Nitrogen-based MAP works by reducing the presence of oxygen, which inhibits the growth of aerobic microorganisms (those that need oxygen to survive). However, the risk of anaerobic microbial growth, particularly for foods stored in low or no oxygen conditions. Proper microbiological evaluation is essential.
Enzymatic Activity
Enzymes naturally present in food can lead to undesirable changes, such as browning in fruits and vegetables. Nitrogen MAP slows down enzymatic reactions by reducing oxygen exposure, though in some cases, enzymatic inhibitors may also be required for complete control.
Moisture Content and Water Activity (Aw)
Moisture migration within the packaging can impact food quality, so selecting the right packaging materials for nitrogen MAP is key. For example, high-moisture products like baked goods require packaging materials with moisture barriers to maintain freshness. Nitrogen atmospheres combined with effective moisture control can prevent dehydration or excessive moisture absorption.
Tailoring the Atmosphere: Selecting the Right Gas Mixture
The correct gas composition in MAP directly affects the quality and safety of the packaged food. A mixture of nitrogen, carbon dioxide (CO₂), and, in some cases, oxygen (O₂) is used, depending on the product’s needs.
Nitrogen’s primary job is to displace oxygen and act as a filler gas. It is inert, stable, and non-reactive, making it a perfect base for MAP in various food categories. Carbon dioxide, on the other hand, is prized for its antimicrobial properties, which help suppress mold and bacterial growth. However, excessively high concentrations of CO₂ can alter product texture and taste. For instance, soft, moist products like bread can absorb CO₂, compromising their quality.
While most MAP efforts aim to minimize oxygen, there are exceptions. For example, a low level of oxygen helps maintain the red colour in fresh meat. Balancing oxygen levels carefully is crucial to avoid spoilage while preserving visual appeal.
Choosing the Right Packaging Materials
Packaging materials play a pivotal role in ensuring the success of nitrogen-based MAP by maintaining the modified atmosphere within the packaging.
- Barrier Properties: Materials should have low oxygen transmission rates (OTR) and carbon dioxide transmission rates (CO₂TR) to maintain the desired gas composition. Multi-layer laminates are commonly used for products requiring extended shelf life.
- Seal Integrity: Gas leakage can compromise the nitrogen-based atmosphere, so strong, uniform seals are essential to maintain packaging integrity.
- Food-Grade Compliance: Ensure all materials are certified safe for direct food contact and meet regulatory standards.
- Package Design: Well-designed packaging formats, such as trays or pouches, can prevent gas imbalances and ensure effective MAP.
Implementing the Technology and Ensuring Quality Control
One of the biggest factors that affects the success of nitrogen-based MAP is the equipment and processes used. Quality control is also essential to ensure the goals of nitrogen-based MAP are effectively met.
- MAP Packaging Machines: Choose machines designed for your specific needs. Popular options include tray sealers for fresh food like meat or produce, flow wrappers for baked goods and snacks, and vacuum chambers with gas flushing for versatile product packaging.
- Nitrogen Generation and Supply: Instead of relying solely on costly nitrogen cylinders or liquid nitrogen tanks, many companies now opt for onsite nitrogen generators which can provide a much lower nitrogen cost.
- Gas Mixing and Control Systems: Accurate gas mixers and control systems are vital for achieving the precise gas formulation required for specific food products.
- Hygienic Design and Cleaning: Equipment should be designed for ease of cleaning to prevent contamination, especially in environments handling high-risk foods.
- Ongoing Quality Control: Frequent monitoring of packaging processes and finished products ensures consistent quality.
- Temperature Control: Maintaining proper cold chain management throughout the supply chain improves the effectiveness of MAP and extends shelf life.
- Shelf-Life Studies: Conduct shelf-life studies under controlled conditions to validate the effectiveness of nitrogen-based MAP for each product.
A Strategic Approach to Nitrogen-Based MAP
Advanced Gas Technologies Inc. has been designing, marketing, installing, and maintaining industrial gas generating systems, standard industrial compressor systems, and engineered compressor systems throughout North America since 1994. Over the years, we have helped our clients reduce their industrial nitrogen and oxygen costs by utilizing leading-edge technologies such as onsite nitrogen and oxygen generating systems.
Are you ready to optimize your nitrogen MAP system? Contact us today to explore how nitrogen MAP for food packaging can enhance your operations efficiently and cost-effectively.