Modified Atmosphere Packaging (MAP) is a core preservation technology for fresh products. By precisely adjusting the ratios of O₂, CO₂, and N₂ to replace internal air, MAP inhibits microbial growth and slows down food metabolism, significantly extending shelf life. The key to success lies in "Category Customization"—different products have vastly different physiological characteristics, and incorrect gas ratios can actually accelerate spoilage.

Based on empirical data, here is a practical guide to the most effective gas compositions:

• Core Objective: Color retention and antimicrobial action.

• Optimal Ratio: O₂ 70% + CO₂ 20% + N₂ 10%

• Performance: Under cold storage (0-4°C), shelf life is extended from 2–3 days (traditional packaging) to 7–10 days. High O₂ levels keep myoglobin active, ensuring a bright red color, while the total bacterial count is reduced by 68% compared to traditional methods.

• Risk Warning: If O₂ drops below 60%, the meat will brown; if CO₂ exceeds 25%, it may cause drip loss and off-odors.

• Core Objective: Suppressing respiratory metabolism.

• Lychees: O₂ 4%–6% + CO₂ 3%–5% + N₂ (Balance)

  • Effect: Extends shelf life to over 15 days at 0-4°C, reducing loss rates from 30% to 8%. Note: CO₂ above 8% leads to skin damage and fermentation.

• Strawberries: O₂ 10%–15% + CO₂ 15%–20% + N₂ (Balance)

  • Effect: Extends shelf life by 8–10 days and increases chlorophyll retention by 25%.

• Core Objective: Controlling bacterial growth and fat oxidation.

• Chilled Salmon: CO₂ 40% + O₂ 30% + N₂ 30%

  • Effect: Extends shelf life from 3–5 days to 10–12 days at 0-4°C; reduces the increase of Total Volatile Basic Nitrogen (TVB-N) by 30%.

• Fatty Fish: To prevent rancidity, O₂ should be eliminated: CO₂ 50% + N₂ 50%.

• Core Objective: Broad-spectrum antimicrobial inhibition without O₂.

• Optimal Ratio: CO₂ 34%–36% + N₂ 64%–66%

• Performance: Requires a gas displacement rate ≥ 98%. At 0-4°C, shelf life can reach 30–60 days—double that of vacuum packaging—while perfectly preserving the original flavor and texture.

• Precision: Ensure the gas mixing error is less than 2%.

• Materials: Must be paired with high-barrier packaging films to maintain the internal atmosphere.

• Outcome: Accurate MAP execution is the most effective way to maximize freshness and minimize waste in the cold chain.