Answers to 10 Common Questions about Storing Food in Mylar Bags – Plus Bonus Tips and Free Labels!
This post contains affiliate links.
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**JULY 2022 UPDATE** – A well-known retailer for mylar bags is discontinuing the sale of solid coloured bags as of August 1st (due to association with drug paraphernalia). While clear mylar still works, the solid ones prevent light from breaking down food, are more durable, and allow you to be more discreet with the contents. I also prefer the ones that have zippers to reseal the bags. Therefore, I recommend buying this set of mylar bags before they are off the site. I purchased this set this week and am happy with the quality and price.
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Let’s talk about mylar bags, oxygen absorbers, and how to work them into your overall food storage strategy. In this blog post, I answer eight common questions and at the end, give you extra tips for success. Hint: I actually use mylar bags sparingly, saving them for specific items and situations. Keep reading to understand my thought process.
First though, if you want a list of all the items you can put in mylar bags and what their estimated shelf lives are, then download this free food tracking spreadsheet. There is one tab dedicated to mylar. You’ll also get colour-coded mylar bag labels!
Mylar Bag FAQ
1. What are Mylar Bags?
Mylar (BoPET film) was invented by the company DuPont around 1955. NASA used it first. We commonly think of mylar bags as being silver in colour, but that is actually the aluminum foil backing that helps block light and reinforce the bag. The actual mylar is a clear polyester resin. (So if you purchase clear mylar, they will still be effective but you’ll have to be more intentional about storing it away from light).
When paired with oxygen absorbers and properly heat sealed, mylar bags are extremely effective at extending the shelf life of dried, low-fat foods, as the food is protected from the effects of oxygen, light, heat and moisture.
2. Where do I buy mylar bags?
I bought mine off of Amazon. They are getting more popular, thus harder to find, so you may need to search a bit. There are also various prepper/food storage websites that carry them.
I like using one gallon (16 cup) mylar bags because they aren’t too small, but also aren’t so big that it would be hard to store the bag in my kitchen while in use or end up being a waste of a bag if the emergency situation was only a few days long. And I like ones with ziplocks so I can open and close them when actively using the food from them.
3. Do I really need oxygen absorbers inside the mylar bags?
To make it worth it to repackage in mylar, yes! Otherwise, you might as well store items in their original packaging or any well sealing container. Oxygen absorbers are not the same as moisture absorbers. Oxygen absorbers actually remove the oxygen from the bag so that all that is left is 99% nitrogen and 1% other gases. This is why a properly sealed mylar bag doesn’t look vacuum sealed – it still looks like there is air inside, but the “air” doesn’t include oxygen, which is the gas that causes food degradation over time. You won’t get that extra long shelf life that mylar provides without also having the oxygen absorbers.
Exceptions: The items that don’t need oxygen absorbers are salt, sugar, baking soda/powder and crystalized (dried) honey.
4. How many oxygen absorbers do I need?
The answer is it depends on the size of your mylar bag or food grade bucket, as well as the density of the food. High density items like flour need less absorbency power than a lower density item like chickpeas. It doesn’t hurt your food to have more oxygen absorbers, so default to more if you aren’t sure.
Oxygen absorbers have different absorption rates. Look for the “CC” on the description. For a more detailed chart, view this source.
300cc – one absorber for half-gallon bags and smaller.
500cc – one absorber for one-gallon bags.
1000cc – one covers 1.5 to two-gallon bags; use two for less dense foods.
2000cc – one covers five-gallon containers with dense food; two for less dense foods.
5. What foods can I store in mylar?
You can find a full list on this free food tracking spreadsheet, but aim for items that have less than 10% moisture. So if you are dehydrating your own foods, you want to REALLY dehydrate them.
Ideal for mylar: Flours (or wheat berries/other grains to grind up into flour), dried lentils and beans, white rice, oats, popcorn kernels, pasta, freeze dried or dehydrated produce, baking basics, powdered skim milk, etc.
General rule of thumb: “Store what you eat.” Don’t store random weird grains and beans you have no clue how to bake with just because you read it lasts a long time in mylar. Make sure you store foods you’ll enjoy eating and can easily work into family favourite recipes.
6. What foods can not be stored in mylar?
You can’t store fatty items like nuts, seeds, oily foods, crackers and chocolate in mylar for long, because the fats go rancid after one or two years at most. I store foods like nuts and chocolate chips in my freezer instead. To extend the freezer life, you can vacuum seal them first. For items like crackers or granola, consider storing basics like salt, seeds, sugar and grains, and learning to make your own (healthier!) crackers.
And of course, you can’t store any moist foods such as fresh produce, canned foods or liquids in mylar.
7. Do I need to freeze grains and flours first?
The internet is really divided on this topic. Many will say that flours need to be frozen first to kill off weevil eggs and other small bugs. You do want to freeze flours first when you are storing them in mylar or other well-sealing containers without oxygen absorbers. But make sure you let the flour or grains come completely to room temperature first. This prevents the food from “sweating” and having moisture buildup that leads to bacteria inside your mylar bags.
Bugs need oxygen to hatch and survive. So oxygen absorbers actually kill off bugs too. From the research I’ve done, it doesn’t appear you need to freeze grains first when properly using oxygen absorbers. Going forward, I’ve chosen to skip the freezing step to simplify the process for myself. I default to higher cc oxygen absorbers though!
8. What size of bags should I buy?
I like one-gallon sizes for most items like beans, flour and grains. I’ve gotten them to hold 16-20 cups of food. I don’t like going bigger otherwise it’s a lot of food you are opening all at once and they are harder to pick up and move. Anything bigger I would be using a food-grade pail instead. Also I like to buy the ones that have the ziplock feature. It’s worth it to have some smaller ones for things like tea. I personally don’t find anything smaller than a half-gallon that useful though.
Mylar bags are sold in different thicknesses. This doesn’t alter the effectiveness of the bags. Thicker ones simply are more durable and harder to puncture. If you get them too thick though, they are harder to heat seal. So thickest is not always best.
9. How do I heat seal the bags?
You can use the seal function on a Food Saver. Don’t vacuum seal first, simply use the “seal” feature to melt the plastic into a seal. There are many reasons to have a Food Saver at home, but if you aren’t ready to purchase that, just buy a simple heat sealer or use an old hair straightening iron (don’t use your good hair iron though, as it may create a residue on your iron that you wouldn’t want on your hair!)
10. What’s the best mylar bagging strategy?
The number one thing you can do to be prepared for a food shortage or other emergency is to simply have a deep pantry. (Read more about starting your food storage in this blog post). In this case, I’m simply using a “first in, first out” rotational system and making sure I have three-ish months of food on hand. So for anything I know I’ll be using within the year, I don’t mylar bag it.
Even though mylar bags and oxygen absorbers aren’t that expensive, I’m still not going to spend the extra time and money on it for foods I plan to open in 6 months.
I reserve mylar bagging for SHTF situations. This is food I buy on top of my regular grocery budget with the intention of hiding it away for an extra rainy day. If no emergency occurs, it will just remain in storage until it gets close to its estimated expiry date, at which point I’d start using it so it doesn’t go to waste.
The amount of food you choose to stash for SHTF situations really depends on the size of your family, other sustainable food sources you have available (ie a garden), and what is going on in your geographical region. Think of it as extra on top of however long your “deep pantry” foods will last.
Extra Tips for Success
The following are extra tips to help you be successful with incorporating mylar into your overall food storage strategy.
A. Wash your hands and arms thoroughly when bagging (and/or wear gloves), then dry your hands really well. This helps prevent bacteria from getting into the clean bags.
B. Do larger quantities all at once. This saves you time and also simplifies what you do with your oxygen absorbers. For example, if you buy a bag of 20 oxygen absorbers, try to do 20 mylar bags in one go. This way, you don’t have to worry about resealing oxygen absorbers (if they are left open to the air, they’ll become useless as they cannot be reused).
C. Don’t forget to measure as you go. When filling the bags, fill them as close to the top as possible, checking to ensure they’ll still close. It’s a good idea to measure so you can write down the precise quantity in the bag. This will also help you with serving math. For example, if you get 16 cups of rice into a one-gallon bag and your family needs two cups of rice to feed everyone at dinner, you know you have 8 meals worth of rice in that bag.
D. Add your oxygen absorbers all at once at the end. This way, you won’t be exposing your absorbers to the air (rendering them ineffective before they’ve gotten into your bags). Here is the order I do it in:
- First stand up the packed mylar bags with the tops open.
- Shake the food down so it settles.
- Open the bag of oxygen absorbers and add them to the mylar bags, pushing them into the food so that they’re covered.
- Close all the mylar bags if they have ziplocks, being careful to press the excess air out.
- Reseal the bag of oxygen absorbers if you have some left.
- Heat seal the tops of the mylar bags.
E. Buy bags that reseal (like these ziplocking ones). This way, when you go to use your food and break the heat seal, you can still reclose the bag. You don’t have to transition it to a different container. As per note C, it also makes it easier to add oxygen absorbers to your bags at the end.
F. Label your mylar with useful information. Keep in mind that you may not be the one who ends up using the food, so it has to be straightforward for anyone.
Include:
- Name of food
- Packaged on date
- Estimated shelf life
- Quantity in bag (in cups or whatever you normally measure with)
- Nutrition label & cooking information
For the last one, I like to cut out the label on the original bag and tape it to the outside of the mylar. Even if I feel confident that I know how to cook with it, its good to have the reminder as it may be someone other than myself who ends up using the food.
G. Store your mylar bags in locking bins. This keeps them safe from water damage or critters like mice/bugs that can chew through plastic. For added security, put them in solid coloured bins and label them with something non-food related, so it isn’t an obvious stash of extra food. (Good for SHTF situations when there is a higher potential for raiders).
H. Save and reuse your mylar bags. When reusing, be careful to not use boiling or very hot water to wash them as you could melt the mylar. Wash with dish soap and warm water. Then let them air dry until totally, 100% dry. Keep in mind that they may store slightly less than they did the first time around, because you will have had to cut off the heat sealed top and will be heat sealing again.
Bonus Gift for You!
This one is for those of us who like to go the extra mile with organization! While you get definitely just write on your mylar bags with a permanent marker, use these printable labels to keep everything readable and organized! They feature:
- Optional colour coding for different food types (ie dried produce, grains, proteins and basics).
- Fillable pdf form so you can improve readability by typing out the info before printing.
- Three labels per normal printer paper-sized sheet.
- All the key info you should remember to include on your mylar packages, for anyone to know how to use and store the food.
Want sticker paper for the labels? I recommend these waterproof printable sticker sheets.
Simply subscribe to the blog for instant access. If you are already subscribed, the printout will now be available through the subscriber only content link you received via email.
I have a question I can not find the answer to any where.
I was waiting for my husband to order food grade dessicants so I could put in to nonfat milk powder
I made the mistake of not looking at the dessicants. I wrongly assumed he had ordered the right ones, so used them.
DO I have to through out the entire contents? I noticed the cooffe beans I used one in, the bag expanded. Those those out too?
Please help me if you can. Don’t want to waste food but don’t want to get sick either.
Thanks!
Aloha,
Michele
I don’t want to give you bad advice, so follow your intuition for whether the food is still ok to eat or not. It’s going to really depend on how long the dried food has been in the mylar. Without oxygen absorbers, the shelf life will be about the same as the original packaging. Desiccant packets like Silica are NOT the same as oxygen absorbers. Desiccants absorb moisture. But you should only be putting very dry foods into mylar bags. If you are putting wet food into mylar, then yes it will go bad quite quickly. Oxygen absorbers absorb the oxygen and leave the nitrogen/other gases. The bag will not completely collapse like in vacuum sealing because the nitrogen is still there. What you want to add to mylar bags is oxygen absorbers as per the chart I link to in this blog post.