Modified Atmosphere Packaging

Fresh produce continues to respire after harvest, and cut surfaces respire even faster. In a sealed package the respiring produce consumes oxygen and releases carbon dioxide. If the packaging film lets gases pass at a rate matched to that respiration, the pack settles at an equilibrium atmosphere — lower in oxygen and higher in carbon dioxide than air — that slows metabolism and decay without starving the produce of oxygen entirely.

The atmosphere can also be flushed with a chosen gas mixture at packing (active MAP), or allowed to develop from respiration alone (passive MAP). Matching the film, pack size, produce type, and temperature is essential, because the right atmosphere for one commodity can harm another.

• Choose a film permeability that matches the respiration rate of the specific produce.
• Match pack fill weight and temperature, since respiration rises steeply as produce warms.
• Avoid oxygen so low that produce ferments or that anaerobic microbes are favoured.
• Keep packs chilled throughout distribution, because temperature abuse changes the atmosphere and shortens shelf life.

Because MAP deliberately lowers oxygen, package design must ensure that the atmosphere suppresses spoilage without favouring pathogens that tolerate or prefer low-oxygen conditions. Fresh-cut produce is handled extensively and eaten without cooking, so hygienic processing, validated temperatures, and clear use-by dating are integral to safe MAP, not optional extras.