Oxygen

Oxygen is the second most abundant gas in Earth's atmosphere (approximately 21%) and is essential for all aerobic life. As a food packaging gas, it plays a distinctive role in modified atmosphere packaging (MAP) for fresh meat products: including oxygen in the packaging gas mixture at concentrations of 60–80% maintains the bright red colour of oxygenated myoglobin in fresh red meat, which consumers associate with freshness and quality. Without oxygen, myoglobin converts to metmyoglobin, producing an unappetising brown colour even in meat that remains safe to eat.

No JECFA numerical ADI is applicable to oxygen as a food additive. Oxygen is a fundamental requirement of human metabolism; it is inhaled continuously and used in cellular respiration. As a packaging gas it introduces no novel chemical entity into food, and residual dissolved or headspace oxygen in packaged food is not considered a food additive in any meaningful toxicological sense.

Oxygen is approved in the EU as E948 for use in modified atmosphere packaging, predominantly for fresh red meat. Its use is selective: while oxygen promotes colour retention in red meat, it also accelerates lipid oxidation and can shorten shelf life if used inappropriately for other products. For this reason, oxygen-containing MAP is specifically designed for beef and lamb and is not used for foods where oxidative spoilage is the primary concern. Consumers should note that modified atmosphere packaging does not involve chemical treatment of the food itself — it is purely a physical preservation technique using gases that are already present in the atmosphere.