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

    1. I’ve been storing foods for over 35 years now, and every so often I test them, Flour can make it 20+ years and still be edible, but that’s the key word, edible is not best, best store time for flour is a max of 15 years, 10-15 is perfect, I opened Flour at 20, 25 & then 15 & 10, the 15 & 10 you could not tell any difference it was the same as new store bought flour, the 20 & beyond again was edible, but if you put them together in a taste test, the 20 and beyond loses hands down by anyone testing it. The finished product like baking bread, biscuits look different, feel different and have either little to no taste or just a bit different taste, not bad, but not good either.

  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 😎🤙🏻

      1. Your wrong about Flour long term, if you’ve never tested it then you should not post about it, I’ve been storing foods for over 35 years now, and every so often I test them, Flour can make it 20+ years and still be edible, but that’s the key word, edible is not best, best store time for flour is a max of 15 years, 10-15 is perfect, I opened Flour at 20, 25 & then 15 & 10, the 15 & 10 you could not tell any difference it was the same as new store bought flour, the 20 & beyond again was edible, but if you put them together in a taste test, the 20 and beyond loses hands down by anyone testing it. The finished product like baking bread, biscuits look different, feel different and have either little to no taste or just a bit different taste, not bad, but not good either. So it’s perfectly fine for up to 15 years, it could even be 16-19 I only opened them after 10-15, 20 & 25 years. the 15 again was fine, 20 I would just rather not eat it unless it’s an absolute have to situation, otherwise rotate it out after 10-15 years. but I’m sure somewhere in the 16-19 year range is when it starts losing everything, exactly what that time frame is could vary by situation and where and how it’s stored and the temp and everything.

  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 🤦🏼‍♀️🙏

        1. gillimcwilli,
          Your flour in Mylar bags and O2 absorbers should be fine. I wouldn’t worry about it.

  9. Can you store self rising flour in a mylar bag with oxygen absorbers?

  10. 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.

  11. 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.

      1. I sealed the Mylar bags before freezing. Freezer first next time! 😉
        Thanks so much!

  12. 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.

      1. I have Vacuum sealed flour many, many times in my 35 years of prepping, not once have I ever had a pack go bad, main thing is no OA, & follow the instructions below and you should not have a problem, of course you can purchase bad items.
        Vacuum Sealing
        Shelf Life: 1-2 years

        The vacuum sealing process removes air from the packaging. The bags are not completely leak-proof; air and humidity will eventually seep through. However, the reduced amount of air means flour stored this way will last much longer.

        Vacuum sealing also keeps insects from getting into your flour. It will NOT kill insect eggs which are already in the flour though. That’s why many people first take steps to kill insects in dry food before storage.

        To store flour with vacuum sealing:

        Place the entire bag of flour into a large vacuum sealer bag. You cannot dump the flour directly into the vacuum sealer bag because the particles of flour will get sucked into the machine.
        Follow your products instructions to vacuum seal the flour.
        Put the sealed flour in the freezer for at least 96 hours. This is to kill any insect eggs which are in the flour.
        If you must remove the flour from the freezer but won’t be using it right away, let it come to room temperature before putting it in any other storage container. Otherwise condensation will form.

  13. 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

  14. 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.

    2. You can leave AP Flour in it’s original bag, just of course use a big enough Mylar bag with OA, cut a slit into the top of the Flour & stick the OA in it, you don’t have to push it more than about 1/2 way down. Once you open a bag of Mylar with Flour, let a little air out, open the bag mouth wide for 10 mins, fluff up bag & let it air out as it will develop an odor sometimes when stored & 1st opened. You can use or seal back up till ready, the zippered Mylar bags are good for this purpose.

  15. 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.

  16. 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.

  17. Okay, doing some Mylar packaging for the first time. I’m trying to figure out whether to dump the flour into the Mylar – or put the whole original bag of flour in the Mylar. Sorry if this is a stupid question.

    1. Sherman,
      Done it both ways, just know that flour may not store well beyond 2 years, lots of factors. If its for truly long term i would go with wheatberries

    2. Sherman
      No question is ever as you put it ‘a stupid question’. We all need the knowledge of others, where by we pass it along.
      Now to answer your question.
      You put the flour into the Mylar bag (5mil or greater) with the 02 absorber then squeeze all the oxygen out and seal across the flap. When I am doing it I will iron about 7/8’s of the bag closed then remove the additional air out and making sure it stays removed, using the iron to finish off sealing of the bag.
      On the flap that I have ironed I will write the date and what the product is inside the bag.
      If you do not wish to use your clothing iron, my other recommendation is a flat curling iron you can pick up are inexpensively.
      You will find on U tube several videos showing how this is done, so you know you are doing it correctly. Hope this bit of information makes you comfortable on this project.

    3. Sherman
      I buy 50lb bags, break it down to 2 1/2 to 5lbs, put is brown paper lunch bag with O2, close the paper bag, tape it, then insert into mylar and seal. I tried without the paper bag, but flour dust kept getting in the seal causing it to fail.
      I have stored up to 5yrs successfully in a cool area.
      No such thing as a stupid question, how you gonna know if you don’t ask?.

    4. Sherman. I started LT Food Storage in 2022. Bit of a learning curve. I use the ones that have the zipper seal for convenience. For flour I fill 30 pounds into a 5 gallon zippered Mylar, add a 2500cc O2, squeeze out the air, use a tissue to wipe away any dust from what’s above the zipper fold, and seal. I leave a lip above the zipper so that I can reclose it when I open it if I need to. I’m storing bread flour like this. I’ll open 1 around summer of this year to see how I did and replace it with 2 more if all is well. Currently have 2 bags (30# each = 60# total) put up. I bake a lot of bread and find bread flour to be convenient so in a SHTF scenerio that’ll be a good go-to for me. *Should note that I store all of my Mylar bags in Tupperware bins too, not 5 gallon buckets like most do.*
      I could probably do the same with AP flour too but I actually keep (2) 25# bags of AP flour in a Tupperware bin in my kitchen (not Mylared), 1 bag stacked on top of the other. Started doing this during pandemic. Slit an opening in top bag to use as needed and when you finish the top bag add a fresh one under the second to keep it cycled. My daughter is a baker too so a 25# bag usually last a few months. I’ve had no issues with 2 year old AP flour.

      Always feel free to ask questions and we’ll be happy to share what we know. I’m the “newbie” poster (2022) and usually get the “I’m the new kid” vibe from most of the other posters, though I’ve probably been a “Prepper” longer than most who post themselves. I learn things in stages and LT Food was my 2022. Think I’ll make canning (properly) my goal for 2023 along with expanding my “Survival Gardening” that I also enjoyed in 2022. Don’t feel bad about asking questions. That’s how we learn. Also from the mistakes of others, which I occasionally make myself as well. ; )

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