How Long Does Rice Last in Mylar Bags? Oxygen Absorbers, Sizes and the Mistakes That Ruin It

Short answer: Utah State University (USU) Extension says that when properly sealed and stored, polished white rice will store well for 25 to 30 years, and that rice kept at a constant 70°F with oxygen absorbers will store well for up to 10 years. The long figure depends on three things: white rice (not brown), an oxygen-free seal, and cool storage. Get any one of those wrong and you are looking at a few years, not decades.

Rice is one of the cheapest calories you can store, which is why it sits at the heart of most long-term pantries. Here is how to pack it so it actually lasts.

Why Mylar and oxygen absorbers work

Stored grain goes off for a few reasons: oxygen slowly breaks down flavour and nutrients, moisture invites mould, and insects hatch from eggs already in the bag. A Mylar-type foil pouch blocks oxygen, light and moisture. An oxygen absorber, a small packet of iron powder and salt, removes the oxygen that is left in the bag. USU's fact sheet on oxygen absorbers says they reduce the air inside to about 0.01% oxygen, which also stops insects from surviving.

The 30-year figure is not marketing. USU cites a Brigham Young University study that sampled polished and parboiled rice stored from 1 to 30 years and found both kept their nutrients and flavour well enough for use.

What you need

• Dry white rice. Polished long-grain or parboiled rice works. Avoid brown rice for long-term storage (see below).
• Mylar-type bags. One-gallon and five-gallon sizes are common. Thicker bags resist punctures better.
• Oxygen absorbers in the right size (see the table).
• A heat sealer or a household iron to seal the bag.
• Food-grade buckets with lids to hold the bags and keep rodents out.
• A marker for labels.

How much oxygen absorber to use

USU's fact sheet gives these starting points:

ContainerOxygen absorber Quart containerOne 50cc packet One-gallon container or #10 can300cc Five-gallon containerThree 500cc packets

Using a little more than you need does no harm. Using too little leaves oxygen in the bag.

Step by step

1. Kill any insects first (optional). USU suggests putting bags of rice in the freezer for three days to kill insects or larvae, then letting the rice come back to room temperature before packing, so condensation does not form inside the bag.
2. Fill all your bags before you open the absorbers. Leave enough space at the top to seal.
3. Open the absorber pack last and work fast. USU says that once the package is open, absorbers should be used within about 15 minutes. Store any unused packets in an airtight glass jar or PETE container.
4. Add the absorber and seal. Press out excess air and seal across the full width of the bag. Check the seal for gaps.
5. Label it with the contents, date packed and absorber size.
6. Check after a few days. A good seal usually pulls in tight around the rice as the oxygen is absorbed. A bag that stays loose may have a leak. Reseal it with a new absorber.
7. Put the bags in buckets and store them somewhere cool, dark and off the floor.

The mistakes that ruin it

Storing brown rice

Brown rice keeps its bran, which contains oils that turn rancid. Extension services give it a shelf life measured in months at room temperature, not years. If you want brown rice, keep a small supply in the fridge or freezer and rotate it.

Packing food that is too moist

USU warns that foods should be below 10% moisture for storage with oxygen absorbers, and that storing high-moisture foods in reduced-oxygen packaging may result in botulism. Dry rice, beans and grains are fine. Never use absorbers with anything damp, cooked or oily.

Using buckets without liners

Oxygen slowly passes through plastic. USU notes that lining PETE buckets with Mylar decreases this exchange. A bucket protects a bag; it does not replace it.

Hot storage

Temperature changes the number as much as packaging does. USU says the best temperature for stored grain is 40°F or below, and its 10-year figure is for a constant 70°F. A garage, attic or a hot island storeroom will shorten shelf life. If you live somewhere hot, store rice in the coolest interior room you have and rotate it more often.

Using old or spent absorbers

USU says unopened absorber packs last roughly 6 months to a year. A used absorber is brown and clumped; a fresh one is a loose pink or grey powder.

Once you open a bag

USU advises using rice within one to two years after opening. Reseal what you do not use, or move it to an airtight container. Use a first-in, first-out system: eat from the oldest bags and replace them with new ones.

How much to store

Rice works best as part of a balanced store with beans, oil, salt and other foods. Our guide to how much food storage per person per month does the calorie math, and emergency water storage made simple covers the water you need to cook it.

Sources

• Utah State University Extension, "Storing White Rice" and "Packaging Foods": extension.usu.edu
• Utah State University Extension, "Oxygen Absorbers" fact sheet: digitalcommons.usu.edu

Frequently asked questions

How long does white rice last in Mylar bags with oxygen absorbers?

Utah State University Extension says properly sealed polished white rice stores well for 25 to 30 years in cool conditions, and up to 10 years at a constant 70 degrees F.

Can I store brown rice in Mylar bags long term?

Not for decades. Brown rice contains natural oils that go rancid, and extension services give it a shelf life of around six months at room temperature. Keep it cold or rotate it quickly.

What size oxygen absorber do I need for a gallon bag?

USU's fact sheet recommends about 300cc for a gallon container or a #10 can, 50cc for a quart, and three 500cc packets for a 5-gallon container.

Is a 5-gallon bucket alone enough?

No. USU notes oxygen slowly passes through plastic buckets. Use a Mylar liner inside the bucket, and use the bucket for protection from rodents and crushing.