What is Modified Atmosphere Packaging (MAP)

I. What is Modified Atmosphere Packaging (MAP)

1.1 Concept

Modified Atmosphere Packaging (MAP) refers to a packaging technology that slows down food spoilage and extends shelf life by altering the gas composition inside the package to make it different from natural air.

It typically uses single or mixed gases such as oxygen (O₂), carbon dioxide (CO₂), and nitrogen (N₂) to replace or partially replace air, thereby controlling microbial growth, enzymatic reactions, and respiration, thus maintaining the freshness and sensory quality of the food. [1][2][3][4]

Typical characteristics include:

The inside of the package still contains "components of air," but the proportions are redesigned;
The internal atmosphere will gradually reach a dynamic equilibrium under the combined effects of product respiration, microbial activity, and film permeability [3];
Packaging materials must possess specific gas transmission rates to ensure gases are exchanged at the designed speed. [5][6]

MAP can be:

Active MAP: "Flushing" with mixed gas (gas flushing) or vacuuming followed by gas filling before sealing;
Passive MAP: Sealing only air, utilizing product respiration to consume O₂ and release CO₂, combined with suitable breathable films, allowing the system to naturally reach the target atmosphere. [1][3][6]

1.2 Differences from Traditional Packaging

II. What are the Advantages of MAP

Synthesizing multiple white papers and reviews, the advantages of MAP are mainly reflected in the following aspects [1][2][5][7]:

2.1 Significantly Extended Shelf Life (50%–400% or even higher)

Typical data from literature and industrial applications:

Prepared ready meals:
Shelf life in air approx. 5 days, up to 10 days with MAP (approx. +100%) [1].
Bakery and Pastries:
4–14 days in air, up to 4–12 weeks with MAP (+ several times) [1][2].
Fresh Red Meat:
Approx. 4 days in air, up to 8 days with MAP (+100%) [1].
Fresh Poultry:
Approx. 7 days in air, up to 21 days with MAP (+200%) [1].
Nuts and Snacks:
Approx. 8 months in air, up to approx. 2 years with MAP [1].
Fruits & Vegetables (strawberries, sliced apples, blueberries, carrots, etc.):
Typically extended several times, depending specifically on gas ratio, temperature, and variety [2].

These extended effects directly bring the following benefits:

Reduced spoilage and return rates;
Supports longer supply chains and larger sales radii;
Reduces frequency of urgent restocking, facilitating supermarket/e-commerce operations.

2.2 Maintaining Sensory Quality and Nutrition

Appearance: High O₂ atmosphere maintains the bright red color of red meat; low O₂ reduces enzymatic browning, e.g., in sliced apples, potatoes [1][2][5];
Texture and Mouthfeel: Appropriate CO₂ concentration can slow down softening; for bakery products, low O₂ + inert gases can slow down staling;
Nutrition: Slows down fat oxidation and vitamin degradation, maintaining higher nutritional levels [2][3][5].

2.3 Inhibiting Microorganisms and Delaying Spoilage

CO₂ has significant inhibitory effects on various aerobic bacteria and molds; the combination of low temperature + high CO₂ is particularly effective [2][5][7];
Low O₂ environment reduces aerobic spoilage bacteria; high O₂ can inhibit some anaerobic or facultative anaerobic pathogens (but strict temperature control is necessary to avoid risks like botulism) [2][7];
By optimizing gas composition and permeability, completely anaerobic conditions inside the package can be avoided, reducing safety risks [3][4].

2.4 Reducing Food Waste and Supply Chain Costs

Extended shelf life → Lower scrap rate, reducing waste at origin, distribution, and retail ends [1][2];
Allows for longer transport and inventory cycles, reducing costs associated with frequent cold chain scheduling;
For large retail and chain catering, it can significantly optimize production scheduling and replenishment plans.

2.5 Enhancing Product Image and Consumer Experience

Transparent packaging + good anti-fog allows consumers to visually assess product quality;
Eliminates need for chemical preservatives, making it easier to emphasize "fewer additives" and "more natural" on labels and marketing;
Suitable for microwaveable, ready-to-eat/cook convenience food packaging formats, increasing product added value [5][7].

Note: MAP cannot "improve the quality of the raw material itself," it only maintains the original quality for as long as possible [5].

III. How to Design Suitable MAP for Different Products

3.1 General Design Approach for MAP

Summarized from multiple design and optimization papers and white papers, a qualified MAP design must simultaneously satisfy three categories of conditions [3][4][5][6]:

Product Physiological and Safety Requirements (Product)
- Food type (meat, fish, fruits & vegetables, bakery, dairy);
- Whether it is still respiring (living tissue: fruits & veg vs non-respiring products: meat, nuts, etc.);
- Respiration intensity (high/medium/low), ethylene production capacity, tolerance to CO₂;
- Target shelf life, target sensory quality, and safety requirements.
Packaging System Parameters (Package)
- Film material type and its O₂/CO₂/H₂O transmission rates (OTR, CO₂TR, WVTR);
- Single/multi-layer, co-extruded/laminated structures and total OTR calculation [5][6];
- Packaging form: Pouch, tray + lidding film, Form-Fill-Seal (FFS), bottles/cans, etc.;
- Package dimensions and headspace volume.
Process & Environment Conditions (Process & Environment)
- Gas filling method: Vacuum gas filling, gas flushing, passive MAP;
- Gas mixing ratio and gas purity;
- Storage & transport temperature and relative humidity;
- Packaging equipment type (vertical/horizontal, snorkel/vacuum chamber/tray sealer, etc.) [1][5].

The design goal is: to enable product respiration/metabolism and gas transmission through packaging materials (including micro-perforations) to reach a steady-state equilibrium, maintaining internal O₂, CO₂, and water vapor within a safe range beneficial for quality preservation throughout the shelf life [3][4][6].

IV. Summary

What is MAP

Modified Atmosphere Packaging (MAP) alters the proportions of gases like O₂, CO₂, and N₂ inside the package, combined with suitable breathable films and processing techniques, to maintain an atmosphere most favorable for specific foods throughout the shelf life, thereby slowing down spoilage and quality deterioration. [1][2][3][4]

Advantages of MAP

Shelf life can typically be extended by 50%–400% or even more;
Significantly inhibits microorganisms and fat oxidation, maintaining color, flavor, and nutrition;
Reduces food waste at all stages, improves supply chain efficiency, and increases product added value;
Facilitates product development directions towards "fewer additives and reduced preservatives." [1][2][5][7]

How to Design MAP for Different Products

Design Essence: Balance product respiration/metabolism with packaging gas transmission to maintain the internal atmosphere within a safe and quality-beneficial range throughout the shelf life;

Can be broken down into:
1) Collecting product and target requirements →
2) Calculating target O₂/CO₂ ranges and target OTR →
3) Recommending gas mixtures and film material structures →
4) Simulation and safety verification →
5) Outputting equipment and process recommendations;

References

[1] What is MAP? & Gas mix guidelines. 332-19-024-UK-Modified-Atmosphere-Packaging-MAP-Helping-you-to-be-retail ready.pdf.
[2] 2.1 Gases used in MAP; Applications in fruits and vegetables. 1958.pdf.
[3] Configuration of a suitable MAP; Design methodology. 54951.pdf.
[4] Packaging materials permeability and selection. 24_modified.pdf.
[5] OTR calculation & polymer engineering & multilayer film OTR. map-white-paper.pdf.
[6] Multi-layer structure and film types. map-white-paper.pdf.
[7] Active/intelligent packaging & antifog & microwaveable MAP. map-white-paper.pdf.