What Are Oxygen Absorbers and How Do They Work?
Oxygen absorbers are little iron packets that scavenge oxygen from a sealed bag. What they are, how they work, and whether they're safe.
Oxygen absorbers are the small packets you see tucked into bags of jerky, and the single most important part of long-term dry storage. Here's what they are and how they work.
What's inside
An oxygen absorber is a small permeable packet filled mostly with iron powder, along with a little salt and activated carbon. The packet lets air in but keeps the powder contained. When it's sealed inside a bag with your food, the iron does one simple thing: it reacts with oxygen.
How they work
The iron oxidises, which is to say it rusts, and rusting consumes oxygen. Inside a sealed mylar bag, an absorber pulls the oxygen level down from the normal ~21% of air to well under 1%. Since oxygen is what lets fats go rancid and pantry pests survive, removing it is what extends dry food from a year to 25 or more years.
Sized by cc
Absorbers are rated by capacity in cubic centimetres (cc) of oxygen they can absorb. You match the cc to your container, roughly 300cc per gallon of dry goods. Our absorber calculator does the sizing, and our best absorbers guide covers which to buy.
They start working the moment they meet air. Once a pack is opened, the absorbers begin reacting with the room's oxygen, so open only what you'll use in one session and reseal the rest immediately.
Are they safe?
Yes. Oxygen absorbers are food-grade and non-toxic, which is why they're packed directly with food. They are not meant to be eaten, and the iron inside can get slightly warm as it reacts, which is normal. Keep unused ones sealed airtight, and check the indicator or feel if you're unsure a packet is still active.
The verdict
An oxygen absorber is a food-safe iron packet that rusts away the oxygen inside a sealed bag, dropping it below 1% and preserving dry food for decades. Size it by cc to your container, seal it in fast, and it does the real work of long-term storage.
Oxygen absorbers are food-safe packets of iron powder that consume the oxygen in a sealed bag by rusting, dropping it below 1% and preserving dry staples for decades. Size them by cc to the container, seal them in quickly, and store spares airtight. They're non-toxic but not for eating.
Frequently asked questions
How do oxygen absorbers work?
They are small food-grade packets of iron powder that react with oxygen in a sealed bag, essentially rusting, pulling the oxygen down to a fraction of a percent. Removing oxygen stops fats going rancid and denies pantry pests the air they need.
Are oxygen absorbers safe with food?
Yes, they are food-grade and designed to sit in sealed food packaging; do not eat the packet. Keep them away from children and pets, and store spares in an airtight jar so they do not exhaust in open air.
Are oxygen absorbers the same as desiccants?
No. Oxygen absorbers remove oxygen; desiccants like silica gel remove moisture. They solve different problems, and for dry-staple storage the oxygen absorber is the one you need. Our oxygen-absorbers-versus-desiccants guide covers when each applies.
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