Food · Food Storage Supplies
Mylar Bags and Oxygen Absorbers.
The quiet pair behind a pantry that keeps for the long run: a bag that blocks light, air, and moisture, and a small packet that takes the oxygen out. They are for dry food only, and that one rule matters more than any brand.
By Dan Whelan, founder of New World Survival
Researched from government agencies, university extension services, and other published sources. See our sources
The basics
What the bag and the packet do, and when you need them.
A Mylar bag is a pouch of plastic film with a metal layer that blocks light and lets very little air or moisture through. You fill it with a dry staple such as rice, beans, oats, or freeze-dried food, drop in an oxygen absorber, and close the top with heat. Penn State Extension notes that Mylar bags block out air and light during storage but must be used with an oxygen absorber. (Penn State Extension)
An oxygen absorber is a small packet of iron powder that rusts as it takes up the oxygen in a sealed bag. Utah State University Extension notes that once the oxygen is absorbed, what remains is about 99 percent nitrogen in a partial vacuum, (USU Extension) so the bag may not look vacuum-packed. Less oxygen means slower staling and a hard place for pantry insects to live.
Most households meet this pair in one of two ways: putting up bulk staples for the long run, or packing up batches from a home freeze dryer. Either way, the bag and the packet do the keeping. They do not make anything safe that was not already dry, which is why the safety section below comes before the shopping.
Quantity guidance
Which absorber for which bag.
Absorbers are rated by how many cubic centimeters (cc) of oxygen they can take up. The Church of Jesus Christ's home storage guidance says absorbers rated for 300 cc work well for properly packaged dry food in containers of up to one gallon. (Home Storage Center) Loose food like pasta and beans leaves more air in the bag than flour or rice, and sellers' charts call for more absorber capacity with it.
| Bag size | Absorber | Good for |
|---|---|---|
| Quart or half-gallon | One 300 cc covers it | Freeze-dried batches, spices, small portions |
| One gallon | One 300 cc; go larger for pasta and beans | Rice, oats, flour, most pantry staples |
| Five gallon, in a bucket | About 2,000 cc, the size the 5-gallon kits we looked at include | Bulk wheat, rice, and beans |
A note on sizing: Smaller bags are usually the better buy. The National Center for Home Food Preservation advises packing dried foods in amounts that can be used all at once, because each reopening exposes the food to air and moisture. (NCHFP) A shelf of one-gallon bags is easier to rotate than a few giant ones. Too little absorber capacity leaves oxygen behind, so when in doubt, round up.
Storage
Keeping absorbers fresh, and sealing bags that last.
An oxygen absorber starts working the moment it meets air, so it begins using itself up as soon as the packet is open. Fill and line up your bags first, then open the absorbers and work quickly. PackFreshUSA's listing, for one, suggests keeping unused packets in a mason jar or resealing their pouch, and doing it right away. A pack of absorbers sealed in smaller sub-packs, five or ten to a pouch, wastes far fewer than one big bag of loose packets.
Close each Mylar bag with heat. Penn State Extension calls for heat-sealing Mylar with an impulse sealer, (Penn State Extension) and on a zipper bag the heat seal goes across the bag, above the zipper. Utah State University Extension recommends thick bags of 5 to 7 mil without clear windows, paired with oxygen absorbers, for the best long-term protection, because windowed bags let more air and moisture pass through. (USU Extension)
Label every bag with what is inside and the date, and store bags somewhere cool, dark, and dry. Mylar is tough on light and air but not on punctures, so many households set filled bags inside a lidded food-grade bucket or tote, which also keeps pests from chewing through.
How a bag fails
Most failures are a seal or a pinhole. Rice and pasta corners can poke through thin film, and a seal made over dust or crumbs may never fuse. Check bags a day or two after sealing. Many shrink and stiffen a little as the absorber works. A bag that stays loose is not proof of a failed seal, since nitrogen remains, but it is your cue to look closely at the seam. A seam that pulls apart, a bag that feels damp, or food that smells off means repack or use it now. The National Center for Home Food Preservation notes that food packaged seemingly "bone dry" can spoil if it reabsorbs moisture during storage. (NCHFP)
What to look for
Three things on the label that matter.
Mylar bags and absorbers are close to a commodity, and dozens of brands sell nearly the same thing. Generic is fine as long as these three checks pass.
Thickness, read carefully
Look for 5 mil or more and no clear window. Read the fine print as well as the title: on November 5, 2026, our top pick's Amazon title said "10 mil" while its own description listed 5 mil bags. Go by the description; 5 mil meets the extension guidance.
Absorbers in sub-packs
Packets sealed in small groups, or one to a pouch for the large sizes, mean you only open what you will use in the next few minutes. A single bag of a hundred loose packets invites waste.
Matched sizes
A kit should pair each bag with an absorber big enough for it: at least 300 cc for a gallon bag and around 2,000 cc for a 5-gallon bag. If the kit's absorbers are smaller, plan on two per bag.
NWS recommendation: Start with a kit of one-gallon bags that already pairs each bag with an absorber, plus a pack of 300 cc absorbers in sealed sub-packs for refills. Add 5-gallon bags and 2,000 cc absorbers only when you are buying staples by the bucket.
Safety
Dry food only, every time.
Taking oxygen out of a sealed bag stops the spoilage organisms that need air. It also creates the low-oxygen conditions in which the bacterium that causes botulism can grow, if there is enough moisture for it. In its guidance for fish products, FDA lists heat-sealed plastic containers among the packaging that creates a reduced-oxygen environment, and names oxygen scavengers among the practices that restrict oxygen in a package. The same guidance notes that drying a product until its water activity is 0.85 or lower prevents the growth and toxin of Clostridium botulinum. (FDA, Chapter 13) Dryness is what makes the bag safe, not the absorber.
In a home kitchen, nobody measures water activity, so the household rule is simple. Ask Extension expert Joy Waite-Cusic puts it plainly: food-grade oxygen absorbers are only recommended for storing properly dried foods. (Ask Extension) Utah State University Extension is just as direct: botulism poisoning can occur if moist products are stored in packaging that reduces oxygen, and food stored in airtight containers with oxygen absorbers must be dry, about 10 percent moisture or less. (USU Extension) If you cannot be sure a food meets that, leave it out.
| Fine in Mylar with an absorber | Never in Mylar with an absorber |
|---|---|
| White rice, dry beans, rolled oats, wheat, dry pasta | Fresh fruit, vegetables, meat, or cheese |
| Freeze-dried food that is dry all the way through | Leftovers, cooked food, or anything with liquid |
| Dehydrated food that snaps or crumbles | Soft, bendable, or sticky dried fruit and moist jerky |
Botulism control per FDA Fish and Fishery Products Hazards and Controls Guidance, Chapter 13. Household rule per Ask Extension and Utah State University Extension. The "never" column is our own cautious reading of that rule. Last verified November 5, 2026.
If you are not sure it is dry
Do not seal it with an absorber. Dry it further, eat it soon, or keep it in the refrigerator or freezer as you normally would. For freeze-dried batches, University of Minnesota Extension describes the check: cut a piece from each tray in half and look for a dark spot in the middle, which means moisture is left. (UMN Extension) USDA FSIS says freeze-dried foods are shelf stable but must be packaged in moisture-proof, hermetically sealed containers. (USDA FSIS)
Around the house
Absorber packets are printed "do not eat" for a reason. Keep spare packets in a closed jar on a high shelf, away from children and pets, and throw away used ones when you open a bag. A Mylar bag is not a canning jar either: it does not make moist, low-acid food safe on a shelf. That is the job of a pressure canner.
Where to buy
Our picks for most households.
Top pick
Wallaby 1-Gallon Mylar Bags with Absorbers
30 bags, 30 absorbers, labels
Heat-sealable 5 mil bags with no window, each paired with a 400 cc absorber, which covers a one-gallon bag with room to spare. More than 2,400 Amazon ratings averaging 4.7. A sensible first kit for rice, oats, beans, and freeze-dried batches.
About $27 for the 30-pack
Absorber refills
PackFreshUSA 300 cc Absorbers
50 packets in five sealed packs of ten
The size the home storage guidance names for a one-gallon container, sealed ten to a pouch so you open only what you need. Food grade, with a storage guide included. About 690 ratings averaging 4.7.
About $19 for 50
For 5-gallon bags
Wallaby 2000 cc Absorbers
Each sealed in its own pouch
One large absorber per 5-gallon bag, vacuum-sealed one to a pouch so opening one never spoils the rest. Pair with 5-gallon Mylar bags inside a lidded food-grade bucket. About 390 ratings averaging 4.6.
About $29 per pack
Prices and ratings from Amazon listings, checked November 5, 2026. Prices change often.
Affiliate disclosure: New World Survival earns a small commission on qualifying Amazon purchases at no cost to you. This helps us cover operating costs and keep building new content. Commission never decides a recommendation, and any reputable brand that passes the three checks above will do the job.
Related
How they fit into your pantry plan.
Mylar and absorbers are the storage layer. The food, the drying, and the rotation habit live on the pages below.
Best Home Freeze Dryers
The machines whose batches end up in these bags.
Bulk Grains
Which staples keep longest, and how to put them up.
Food Rotation
Dating every bag and eating the oldest first.
Freeze-Drying
How to tell a batch is dry enough to seal.
Dehydrating
Drying food thoroughly before it goes into a bag.
Vacuum Sealers
The other way to pack dry food, and what it cannot do.