Flour Storage Best With Mylar Bags

Reader Question: I am interested in Mylar bags. My question is if we could store flour because I know the flour goes bad in 6 months to a year. Another thing I want to know, I don’t have any food grade buckets so could I store it in can buckets? Or could I store the food in the Mylar bags and leave them in the basement without any buckets?

What is the storage life of flour?

All-purpose flour (white) in cabinet storage will have a shelf life up to 8 months if properly stored in a sealed container or if tightly wrapped, and for refrigerator storage, up to one year.

Freshly ground whole wheat flour, if stored at room temperature with plenty of access to oxygen will, after a few weeks or months, goes rancid.  That rancidity is caused by the oxidation and breakdown of the oils in the wheat. Any flour milled from whole grains contains the germs. These are rich in oils (which is one of the benefits of freshly ground flour) and are prone to oxidation or – more commonly – going rancid. Depending on a few factors you can expect a storage life of 4 to 6 weeks.

Don’t try to store unprotected flours longer than a year. Hermetically sealed (for example: Mylar bag) in the absence of oxygen, plan on a storage life of 5 years at a stable temperature of 70 degrees F. They should keep proportionately longer if stored at cooler temperatures.

For optimum shelf life of flour, procure and store the whole grain itself (wheat berries) and do not grind the flour until you need it. Of course you will need a grain mill for this. Whole grain does not lose nutritional value in storage, whereas once ground into flour, the nutrient level begins to drop dramatically. Whole grains will store for decades in an oxygen free environment.

Mylar bags

Use Mylar bags and oxygen absorbers for an oxygen free environment. Air contains about 78% nitrogen and 21% oxygen, leaving about 1% for the other gasses. If the oxygen is absorbed (with the oxygen absorbers in a sealed Mylar bag), what remains is 99% pure nitrogen in a partial vacuum. Perfect for long term food storage.

Mylar bags do not need to be stored in food-grade buckets. The Mylar bags themselves are the barrier between the food and the outside environment, so long as they are sealed. You could leave the Mylar bags in the basement with no buckets, however I would not put them directly on a concrete floor (use a board or shelves) to avoid the potential of condensation due to the temperature difference between the cold floor and the air (even though most of the air is removed – it’s still a risk). Also, a bucket will serve as protection from the bag becoming punctured, especially from curious rodents.

Note that any sealable bag will work (seal-a-meal type vacuum sealer machines), as long as it holds a vacuum.

How To Seal A Mylar Bag


  1. we’ve bought enriched white flour from augason farms via costco before and have had good luck. the buckets are crazy hard to get into. we are on our 2nd of 4 buckets. otherwise, we are stockpiling canned wheat from a mormon cannery for super long-term.

  2. I also put Flour in mylar and didn’t know that you weren’t suppose to use self rising. Mine has been kept fairly cool so I feel confident that it’s still okay. How long do you think it will keep if it is kept cool?

    1. @Thelma, I found this information:

      Baking powder has an indefinite shelf life when kept free of moisture and contamination. Baking powder has a best-if-used-by date of 18-24 months. A BYU study examined the leavening power of baking powders stored for up to 29 years in their original cans. All samples successfully leavened biscuits and demonstrated carbon dioxide evolution in lab experiments. Once opened, baking powder will last for approximately six months. To test opened baking powder, mix 1 tsp. in 1/3 cup warm water. If bubbles form, there is activity left in the baking powder.

      Since self rising flour contains baking soda, my interpretation is that the baking soda would lose its effectiveness over a 6-month period in a normal environment. However if the flour/baking-powder mixture is stored in sealed mylar bags in an oxygen-free and dry environment (flour is dry), then I believe you may be Okay. This seems reasonable because ‘they’ say that baking powder will last years or indefinitely if sealed in its original container.

      By the way, the recipe for self rising flour is…
      1 cup all-purpose flour
      1/2 teaspoon salt
      1 1/2 teaspoons baking powder

  3. I have always kept my flour in the freezer, as well as cake mixes,potato chips, and any other dry good sealed. I make delicious pie crust oust of frozen all purpose flour. I have never had a problem. Some has been in th freezer for 2 years! Good luck

  4. I keep self rising flour in Mylar and after about three years or so it won’t brown when used as a coating for frying. I think it has something to do with the oxygen absorbers.

  5. I put my mylar bags filled with the flour in the freezer and I took one out, it was a little moist, but let it come to room temp. is this alright to do?

    1. Sally,
      yes and no,
      usually, flour isnt worth trying to save long term because it doesnt keep real well, most folks store the whole grains, like white wheat or red wheat, they keep indefinitely, the flour is usually only good for a year, maybe two at the most. Just my experience, lots of times if you want to keep the flour from getting buggy, keeping it in the freezer is good, pullit out, measure out what you need, then put it back, I stick the bag of graininthe freezer, 1 week, then bring it out and let it sit for a week, then pack in mylar in a 5 gallon bucket with oxygen absorbers and desiccant packs. Stuff should keep forever about 😎🤙🏻

  6. I’ve got a stash of flour in #10 cans from the LDS store. Runs more or less (depending on if bought in-store or on-line) twice the cost of flour at local grocery store. I figure it breaks pretty close to even compared to purchasing, freezing, packing in mylar with oxygen absorbers, and then into buckets with lids. Convenient. Comes six 4-lb cans in a case.

    1. I’m curious if and what LDS says about their milled flour shelf life sealed in those #10 cans?

      I store wheat (berries) for the long term (lasts decades) and then mill it to flour as needed. Although we do also keep regular ground flour in some bulk quantities too.

      1. Ken, with optimum storage environment – cool and dry – it’s 10 years. But as with any preserved food product YMMV. I also have stacks of their canned wheat berries – 25 year shelf life on those.

  7. I stored organic all purpose flour in Mylar bags with oxygen absorbers and stored them in metal bins approximately 8 months ago. I grabbed one last week- and it was rancid. What did I do wrong? The oxygen absorbers worked and the bags looked vacuum sealed. So disappointing

    1. DEE ,
      It’s possible that mylar bag got a small hole in it somehow. Had that happen with Krusteaz pancake mix. Bought 2 bags at the same time. One was bad but the other was just fine.
      (That company’s customer service was awesome btw!)
      Have you opened another one?
      I would check to see. That bag may just be an anomaly…

  8. I do not know if this question has been asked already, but here goes. Does condensation permeate mylar?

    1. No. However, if the “stuff” inside contains too much moisture, exterior temperature and storage conditions could, in theory, cause some condensation inside. This is not usually a problem with normal “dry goods”.

      Tip: Don’t store the buckets directly on a concrete floor. The cold floor might cause the aforementioned condition, depending… I’ll set them on wood, or anything that will create some amount of minimal insulation between the bucket and a concrete floor. You can also buy some of that hard-pressed insulation foam-board (usually 4×8 sheets) and cut/slice to fit.

      Tip: If you temporarily freeze dry goods such as white-rice first (which destroys any ‘bugs’ or eggs – if they exist in the first place), be absolutely sure that you let it dry out afterwards. Let it come back to room temperature for at least several days before packing.

      1. Oh no! I just packaged everything in mylar bags with oxygen absorbers, put them in tubs and set them outside to freeze. I thought it would be better to do it that way vs setting outside to freeze in their original 25-50lb paper bags. I hope it will be ok 🤦🏼‍♀️🙏

  9. Hello – I have (2) 5 lb bags of Organic White Flout that I would like to put in Mylar bags with oxygen absorbers. I put the flour outside for a week to freeze any eggs. I brought the flour inside for packing and was going to wait a few days before I did this. There doesn’t appear to be any moisture on the paper bag, but is there anything else I can to to be sure there isn’t mold other than putting it in the oven to dry it out? Should it be fine if I leave it out for 3 days before I pack it?

    1. Annie,
      Hopefully the air was dry outside while you had the flour out there in subfreezing temperatures. If you’re confident of that, I would tend to believe you’re good-to-go, after having reached room temperature inside – assuring that everything’s dry.

  10. Hi, Hoping I didn’t do this incorrectly! I packaged 3 Mylar bags with white flour and O2 absorbers then placed them in the freezer to kill any bugs, just to be safe. My plan is to store the bags in food safe buckets. Should I have done the freezer thing prior to packaging in the Mylar bags? Thanks!

    1. Ginger:
      Normally one would freezer the flour first, but your sequence should not be a problem.
      Assuming you sealed the Mylar bags before freezing.

  11. What about Whole Wheat Flour? The LDS store says you should not put whole wheat flour in Mylar bags. The oils can create moisture which can cause botulism. What is the best way to store whole wheat flour for long term?

    1. Tony75
      Your wheat flour can be frozen for a few days in the freezer. Then the bag(s) are brought out to be set aside so they can rise in temperature. After they have been out for at least 3 days or more you can put the flour into Mylar bags, with a 02 absorber. Remove the rest of the oxygen from the bag to point it is closed. When you have finished sealing it, it is ready for long term storage.
      Be sure to write on the package what it is and the date you put it up.

    2. Flour as a rule generally does not keep indefinitely like wheatberries do, it will keep a long time, depending on a whole slew of factors, but to truly have long term viability just store wheatberries

    3. Tony75 – What Kula said. I recently went through my flour for rotation, had to throw out a bunch. All of it was 3-4 years old, vacuum packed and stored in a cool dark environment. All developed noticeable notes of funk offensive to the nose and palate. If you want to store whole wheat, why not store it – whole. Wheatberries can last decades. Run it through a countertop mill and you will always have the freshest flour.

  12. Tess… Good question. I looked at the ingredients on the brand that I use. First ingredient is brown rice flour. I’m going to freeze mine. Thank you

  13. Does the AP flour have to be removed from its original paper bag before sealing in Mylar with O2 absorbers? If so, why?

    1. No one has answered this question and I was wondering the same thing. I have Bob’s Red Mill all purpose flour, which comes in a lined bag. I would like to store five, 5Lb bags in each mylar. Years ago, I dumped all the flour in a large mylar, with 02’s sealed the mylar and stored in food grade buckets, which I now understand was over=kill. Anyone out there try storing in the original packaging, then add the 02’s and seal the mylar?

      1. Ariel,
        i don’t see what it would hurt as long as you freeze them first for at least two weeks at – 0 deg first to kill any weevils and eggs that may be in there. some food grade diatomaceous earth sprinkled over it may help.
        in food storage, there is no such thing as to much or overkill.
        have you pulled any of the flower out and checked it?
        it would be good info for the rest of us to know how it worked out. thanks in advance.

      2. Ariel, The food storage companies store flour, and say it is good for X number of years.( I have not bought any- this type.) If we have killed the larvae, stored sealed in oxygen free package. sealed and it remains so. It should be good just as long as theirs is.
        The Way you did it was smart…5 gallon bucket will let Oxygen in/out eventually. Mylar can become punctured laying in a tote or on a shelf. If it is over 5 years old i would begin using it and rotating it out and replacing- just before i opened another one- to always have my basic supply to where i wanted it…. that is just me… i am not there on some items yet.

  14. So I know I’m going to catch grief on this, but what’s the deal with AP flour for long term? I bought a 25 pound bag at the start of the pandemic and am just finishing it up now. It’s stored in the original bag cut open in a Tupperware bin. Heck I bought another 25 pound bag and put under it a few weeks ago for when it does finish off. Figured I’d get another 2 years out of it. Hasn’t seemed to have gone bad. Cooks and rises fine. No bad taste. I used it a few weeks ago to make a homemade chocolate cake. So is there a particular reason it’s not good after 1 year or am I just lucky?
    I suppose another reason that I’m asking is because I bake a lot of bread (bread machine) using bread flour and decided to Mylar 30 pounds of it to store for LT experiment. (I’ve used 1+ year old bread flour with the same results as the stated AP. Just used a little more yeast.) I did (2) 30 pound bags like this. I plan to open one next year around the June time period and start the rotation on it. Figuring 30 pounds should run about 6 months. Open it. Check it. Refill another one for the next cycle (maybe around June 2024) if good. Ditto with the bag for around December\January. In each bag I placed 2 dessicant packs on the bottom, filled with 6 bags of bread flour, dropped (2) 2,000cc OA (4,000cc total) and sealed it. It was nice and tight when I stored it.
    So asides from possible weevils what other hazards am I missing and why hasn’t the 2 year old AP flour killed me yet?

    I did learn with the whole wheat flour. It did go rancid after a few months. I made crackers with it for the birds. Waste not want not. Now I grind red wheat berries to mix in for my wheat breads. Didn’t care as much for milled wheat flour anyways.

    Ok. Let the griefs come…

    1. And please don’t think this sounds like I’m undermining anyone or the professionals. I really am curious if anyone has ever had any similar experiences or if it’s just me.
      Then again I grew up with a granny that cooked grits, weevils and all. Maybe I’m just immune.

      (No, I wouldn’t make weevil bread. Although the idea of extra protein…)

    2. Conditions,
      Had some that was 5 years old and tasted fine, worked fine, then had another only 2 years old was just off, no clue why.
      My LTS is wheat berries and oat groats

      1. Kula,
        On your LTS, did you pack in mylar with diatomaceous earth and O2 absorbers? Getting ready to do 150# of wheat berries over here.

  15. Just Max, Looking at the “best by” date? Well, that’s also the “tastiest by” date. Note they don’t give you the “it’s still okay by” date or the “it’s barely edible by” date. Then there’s the “not quite nasty by” date, which they don’t tell you either. When it’s yucky, you’ll know. . . .
    As for weevils, taking the flour down to freezing temp will kill bugs and larvae. Then bring package back up to room temp and hold for a few days. This lets any ice crystals dry out of it. Then package for LTS. Over time, weevils and beetles in grain products can eat the best parts of the grain, produce generations of bugs, and leave you with a grain husk, bug carcass, and insect poop filled bag. By then it looks and tastes nasty. From personal experience I can tell you that’s true with rolled oats, about my fav grain.

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