When it comes to storing your emergency food stockpile, there are a lot of different methods you can use. However, the most popular method is sealing food in a Mylar bag.
If you are new to Mylar bags, here is everything you need to know to get started – including step-by-step instructions for packing food in Mylar bags, shelf life, and how to use oxygen absorbers.
- 1 What is Mylar?
- 2 Why Mylar is Great for Long-Term Food Storage
- 3 What Foods Can You Store in Mylar Bags?
- 3.1 Not Suitable for Long-Term (5+ Years) Storage
- 3.2 Mylar Bags and Botulism Risk
- 3.3 Shelf-Life of Foods in Mylar Bags
- 4 Removing Oxygen
- 4.1 Foods which Should NOT Be Stored with Oxygen Absorbers
- 4.2 Oxygen Absorbers vs. Gas Purging/Nitrogen Flushing
- 4.3 How Many Oxygen Absorbers To Use?
- 5 Sealing Mylar Bags
- 6 Step-By-Step Instructions
- 7 Which Mylar Bags to Use?
- 8 How Much Food Will Fit in a Mylar Bag?
What is Mylar?
As one man aptly said in a survival forum, Mylar is
Every prepper’s favorite kind of plastic. I know I have been trying (unsuccessfully) to get my wife to dress in it for years.
I’m not sure how it would work for a dress, but Mylar certainly is a versatile material. The trade name for Mylar is biaxially-oriented polyethylene terephthalate. It was originally produced in the 1950s and is used for things like insulation, solar filters, blueprints, and even kites.
Why Mylar is Great for Long-Term Food Storage
As far as food storage goes, Mylar is amazing because it is:
- Impermeable to gas
- Reflects light
- Durable and puncture-resistant
- Easy to use
There are certainly other packing materials you can use for long-term food storage, but they tend to have a higher learning curve, are more expensive, or simply not as good as Mylar.
Mylar vs. Vacuum Sealing
Many people confuse Mylar bag storage with vacuum-sealing. They are completely different processes and get different results.
With vacuum-sealing, you are using a machine like a FoodSaver (Amazon Link) to suck air out of the bag while sealing it. While this does have benefits (like being cheap and fairly easy to do), it isn’t the best option for long-term food storage.
- Leak: The plastic bags used in vacuum sealing are porous. You can’t see the little holes but, over time, vacuum sealed bags will allow air to leak through.
- Don’t remove all oxygen: Vacuum sealing will remove most air (which includes oxygen and nitrogen) from the package. However, some air will remain.
- Allow light through: The bags used in vacuum-sealing are clear – which is great if you want to see what’s packaged inside, but not great if you want to prevent food degradation from light.
By comparison, Mylar bags will not leak. When used with oxygen absorbers, virtually all oxygen will be removed. Finally, Mylar has a foil layer which blocks 100% of light from coming through.
This doesn’t mean that vacuum-sealing isn’t good for food storage. Vacuum-sealing can increase shelf life of foods by 3-5 times. But, when it is long-term storage that you want (5+ years), then Mylar is the way to go.
What Foods Can You Store in Mylar Bags?
Any dry, low-fat food can be stored in Mylar bags. That means things like:
- Dehydrated fruits and veggies
- Dried beans
- Powdered milk
Remember the key words here are dry and low-fat. Any food which has moisture in it may start to go bad in the Mylar bag.
The same goes for foods which have fat in them – the fat will cause the foods to go rancid in around 3-12 months.
Not Suitable for Long-Term (5+ Years) Storage
These foods can still be stored in Mylar bags, but you’ll have to rotate through them about every 2-5 years (depending on the food).
- Whole-wheat flour
- Pearl barley
- Brown rice
- Brown sugar
- Chips and greasy junk food
- Dried meat/jerky
- Fresh or wet foods
- Dried eggs
- Milled grains (other than oats)
- Any dehydrated fruit or veggie which is not so dry that it snaps when bent!
Mylar Bags and Botulism Risk
Botulism is usually only talked about in regards to home canning. However, because the botulism bacteria grows in no/low oxygen environments, it could also grow in Mylar bags packaged with oxygen absorbers.
Botulism requires moisture of 35% to grow. However, to play it safe, virtually all food preservation guides will say that food must have 10% or less moisture to be packaged in airtight containers with oxygen absorbers. (1)
This shouldn’t scare you away from self-storing foods with oxygen absorbers. Just make sure you aren’t storing any moist foods in Mylar with oxygen absorbers for the long-term.
Some moist foods – such as dehydrated fruits — can still be stored in Mylar bags. They will be fine for the semi long term (such as up to five years). Home dehydrated fruits and veggies just need to be so dry that they snap when bent.
The good news is that botulism toxin (which causes the disease) can be easily destroyed by boiling for 10 minutes. (2) Many of the foods which get stored for long-term need to be boiled anyway (dry beans, dry grains, etc.), so this in theory would kill any contaminants.
However, that doesn’t mean you should eat any foods which you suspect are contaminated with botulism. If the Mylar bag is bulging (a sign that bacteria is growing inside), then don’t eat its contents!
Shelf-Life of Foods in Mylar Bags
When trying to figure out how long foods will last in Mylar bags, you will see a lot of different ranges given. Here’s why it is so difficult to give an exact number of years that food will last.
1. Nutrients Break Down Long before the Food Goes Bad
Part of the reason for these varying shelf-life dates is because nutrients can break down. For example, the nutrients in rice may start to degrade after 10 years. However, the rice will still be safe to eat for approximately 30 years.
2. Mylar is a New Product
The process of checking how long a food will last is called shelf life testing. Big manufacturers are required to do shelf-life testing. However, aside for a few studies on canned foods, there haven’t been any tests on how long food can last.
Also consider that Mylar is a relatively new product (it was made in the 1950s). We think some foods will last 30+ years in Mylar, but I don’t know of anyone who actually tested food that they packaged in the 1980s!
3. It Depends on Packaging Conditions
Mylar only protects food from degradation due to oxygen and light. Assuming that you used oxygen absorbers correctly and properly sealed the bag, you still have to worry about degradation from heat and moisture.
According to the USDA, each 10.08 degree F increase in temperature will half the storage life of seeds. This applies to other foods too. So, if you are keeping your Mylar bags in a cool area (such as a root cellar), they will last longer than if stored in a hot area (such as your garage).
With these factors in mind, here is what you can reasonably expect in terms of shelf-life for foods in Mylar bags.
|Food Type||Shelf-Life (in sealed Mylar bag with oxygen absorbers)|
|Hard Whole Grains (Dry corn, buckwheat, hard red wheat, soft white wheat, kamut, durum wheat, spelt)||10+ years|
|Soft Whole Grains (Oats, quinoa, rye, barley)||8+ years|
|Professionally-Dehydrated Vegetables||10-20 years|
|Professionally-Dehydrated Fruits*||10-15 years|
|Home-Dehydrated Fruits and Veggies*||2-5 years|
|Freeze-Dried Fruits and Vegetables||25 years|
|Legumes (Beans, lentils, chickpeas, split peas)||25+ years|
|White Rice||10-30 years|
|Brown Rice||2-5 years|
|White Flour||10-15 years|
|Whole-Wheat Flour||10 years|
|Corn Meal||5-10 years|
|Potato Flakes||30 years|
|Dry Non-Fat Milk||15 years|
|Cheese Powder||10-15 years|
|Powdered Eggs||5-10 years|
|Nuts **||1-5 years|
|Baking Soda, Baking Powder||30 years|
*Dehydrated Fruits and Vegetables in Mylar Bags
Most dehydrated fruits and veggies usually aren’t suitable for long-term storage. They simply contain too much moisture.
Many people report that their dehydrated fruits/veggies last much longer than 5 years. However, it’s important that they have very low moisture (10% or less) before storage. That means the fruit/veggie will snap when bent.
Some people also recommend using a desiccant to remove moisture from the dehydrated fruits/veggies before packaging. More on this later.
**Nuts and Seeds in Mylar Bags
Putting nuts and seeds in Mylar bags will extend their shelf life. However, because they contain so much oil, they will start to go rancid.
Most people put the shelf life of nuts/seeds in Mylar at about 2 years. However, some nuts and seeds will last longer than this even outside of a Mylar bag. The key is keeping the temperature low.
Since nuts are so expensive, I wouldn’t want to risk having an entire batch get destroyed. Only package as much as you actually eat and rotate through them regularly!
Mylar bags only work for long-term food storage if the oxygen has been removed from the bags. To do this, you need to use oxygen absorbers.
Oxygen absorbers are little packages containing iron. When you put the oxygen absorber (OA) into an airtight container, the oxygen molecules “stick” to the iron. OAs can reduce the amount of oxygen in a container to less than 0.01%. (6)
Keep in mind that air is about 78% nitrogen, 21% oxygen, and about 1% other gases. Oxygen absorbers only remove the oxygen. The nitrogen will remain, thus you often won’t get a vacuum seal. However, nitrogen does not cause food to spoil.
Note that not all foods are oxygen sensitive. For example, whole grains, peas, and beans aren’t too sensitive to oxygen. If you plan on using the foods within 5 years, there won’t be too much difference in freshness regardless of whether you use an OA or not.
However, oxygen absorbers do protect against pests and have other benefits. Since OAs are pretty cheap, it is smart to use them anyway.
Benefits to Using Oxygen Absorbers:
- Keeps food from degrading due to oxidation
- Prevent mold and bacteria from growing on the food (mold and most bacteria require oxygen to grow)
- Preserve flavor
- Prevent vitamins from being destroyed by oxidation
- Kill pests (tiny pest eggs which are invisible to the eye may be on your food; without oxygen they cannot hatch)
Foods which Should NOT Be Stored with Oxygen Absorbers
- Salt: Will become rock hard if stored with an OA
- Sugar: Also will become rock hard; brown sugar also contains too much moisture for storage with OAs
- Baking soda/baking powder: These may explode when stored with OAs
- Wet foods: Foods with moisture of 35% or more can grow botulism in airless environments. To play it safe, it is recommended that foods stored with OAs have 10% or less moisture.
Oxygen Absorbers vs. Gas Purging/Nitrogen Flushing
I’ve recently come across many guides and videos about gas purging (aka nitrogen flushing) Mylar bags. The basic idea is that you use a special machine to force nitrogen gas into the package. The nitrogen flushes out any oxygen. Then you seal the package so only nitrogen remains.
Nitrogen flushing is used by some food manufacturers to keep their greasy foods (such as chips) fresh for a long time. That’s why bags of chips are puffy when you get them.
However, unless you have access to professional equipment, nitrogen flushing is very difficult to do! You have to displace all of the oxygen and make sure none gets back into the bag before you seal it.
Packaging with oxygen absorbers is much easier, and leaves just nitrogen in the packaging. Don’t mess with what works – use oxygen absorbers for your home food storage and leave nitrogen flushing to the experts. (7, 8, 9)
How Many Oxygen Absorbers To Use?
Here is where things can get confusing: For food storage to be successful, you need to have enough OAs to absorb all of the oxygen in the Mylar bags.
Oxygen is in the Mylar bag in two ways:
- In the space between the food
- Inside the actual food
To figure out the correct amount of OAs you can do some tricky math or just use our handy graphic and table instead. (I have included the math in a dropdown for those who are interested)
It is always best to play it safe – use more oxygen absorbers than you think you need! Using extra oxygen absorbers won’t impact the food. OAs are cheap, better to spend an extra 25 cents on an additional oxygen absorber than throw away 5 gallons of food when it’s needed most.
|Food Type||1 quart||1 gallon||5 gallon|
|Beans, lentils, split peas||125-150cc||500-600cc||2500-3000cc|
|Instant mixes and powders||100cc||400cc||2000cc|
|Whole grains (barley, corn, wheat, oats)||125cc||625cc||2500cc|
How to Save Unused Oxygen Absorbers
The moment you take oxygen absorbers out of the package, they will start to absorb oxygen. After around 2-4 hours, they’ll have absorbed their maximum capacity of oxygen.
It is important that you have a plan on what to do with any unused oxygen absorbers before you begin working.
Ideally, you will reseal oxygen absorbers in the packaging they came in. Then you vacuum seal them.
If this isn’t an option, you can also store unused oxygen absorbers in a mason jar. Fill up any extra space in the jar with marbles (or something similar). The less air that is in the jars, the less air the unused OAs will absorb. Be sure to seal the jar tightly!
How to Tell If Your Oxygen Absorbers Are Still Good
If you buy OAs from a reputable company, they should be good. We like the supplier DiscountMylarBags, they are the cheapest around and provide good quality products. They also sell on Amazon if you prefer to shop there)
They will arrive in a vacuum-sealed package. Most oxygen absorbers have a “margin for error” added into their abilities (DiscountMylarBags use ShieldPro absorbers they absorb 200 to 300% of their rating). So, they will actually absorb more than specified. This is so you can have a good 10-20 minutes to work with the OAs and not have that air exposure count against you.
Here’s how you can check:
- They arrive in a vacuum-sealed package.
- The oxygen indicator is pink or red and not blue.
- The packets feel soft and not crunchy.
Sealing Mylar Bags
The trickiest part of using Mylar bags for long-term food storage is sealing them. They must be sealed with heat in order to create an air-tight seal. Even the Mylar bags with zip seals still need to be heat sealed (the zip is just there for convenience).
According to Top Mylar, you need a temperature of around 375-425 degrees F to get a good seal. Thicker Mylar bags will require a higher temperature.
There are 4 main ways that you can seal a Mylar bag:
1. Clamshell Heat Sealer
This is by far the easiest way to seal a Mylar bag. They are great because they are hand-held. They also squeeze, which helps grip the bag.
It makes it very easy to close the last 2 inches of the Mylar bag after you’ve squeezed out the air.
This clamshell sealer is a bit pricey, but it is very easy to use.
It has two heat settings. The higher one is 410F, which is perfect for sealing Mylar bags.
Check On Amazon
2. Impulse Sealer
I personally wouldn’t recommend impulse sealers. Not only are they expensive, but they are designed to seal an entire bag at once.
Ideally, you should seal most of the Mylar bag, push the air out, and then seal the last 2 inches. This takes some practice with an impulse sealer.
There are some affordable impulse sealers available which get good reviews. For example, this one by Metronic is well liked and doesn’t cost much.
4. Hair-Straightening Iron
While I personally don’t have experience using one of these for sealing Mylar bags, it seems like it would be better than a normal iron. You’d be able to keep the bag vertical so bits of product don’t get into the seal area.
Just make sure you get a hair-straightening iron with adjustable heat settings. This one, for example, gets up to 450 degrees F at the highest setting.
3. Home Iron
If you’d rather not buy a special product for sealing your Mylar bags, a home iron will work. You’ll need to have a piece of wood to put the Mylar bag against while sealing.
Also be warned that, since you’ll be sealing the bag as it lies horizontally (as opposed to being able to keep it vertical), you might end up with bits of product shifting into the area you are trying to seal.
It’s not impossible to do. However, it can be a bit frustrating – especially when you are trying to work fast because of the oxygen absorbers!
This video demonstrates the process:
- Food that you will be storing
- Mylar bags
- Oxygen absorbers
- Bucket or container (that you will be putting the Mylar bags into)
- Sealer (clamshell sealer, iron, hair straightening iron)
- Work gloves
- Piece of wood with a towel wrapped around it (to serve as an ironing board if using an iron for sealing)
- Scoop or funnel
- Permanent marker for labeling
- Mason jar (or other way to store unused oxygen absorbers)
Step 1: Preparation
It is really important that you get everything set up in an assembly line. You can take your time filling up the Mylar bags. But, once you open those oxygen absorbers, you need to seal them quickly!
- Open Mylar bags and put each in a bucket/container
- Line up the containers
- Make sure your sealer has a cord long enough to reach the buckets
*If you are going to put lots of smaller Mylar bags into one bucket, then you obviously won’t be propping up one bag per storage container. It’s really helpful to have the bags propped up during the process. Consider rigging a shelf system for holding the bags, or bust out all of your Tupperware to use as holding trays for the open Mylar bags.
Step 2: Loading the Food
- Using a scoop or a funnel, fill up the Mylar bags with food. You’ll need to give the bags a good shake to ensure the food particles are settled (which means more food per bag and less air).
- Fill the bags to about 4-5 inches from the top. Make sure you don’t overfill the bag or it will be very difficult to seal.
- Label the bags and container with the contents plus the date.
- If you are using 7.5mil Mylar bags, wear gloves! The bags are sharp and can easily slice your fingers!
- To protect the label from rubbing off, put a strip of clear packing tape over it.
Step 3: Partially Seal Bags
Let your sealer heat up. Irons and hair-straightening irons need to be on the highest setting. Seal all but the last 2 inches of the Mylar bag. Make sure there aren’t any little pieces of food in the seal.
It is also smart to wear gloves during sealing. The sealer can make the Mylar bag get very hot and burn your fingers!
If Using an Iron: The easiest way to seal with an iron is to put your 2×4 over the rim of the 5-gallon bucket. This will make an ironing board so you can seal the bag without having to lift it out or turn it horizontal. Once you’ve sealed one bag, then just move the board to another bucket. You’ll definitely want help – one person moves the board and the other does the sealing.
Tip: Make sure you seal as close to the top of the bag as possible. That way you’ll have room to reseal the bag again.
Step 4: Add Oxygen Absorbers
It takes about 2-4 hours for an oxygen absorber to do its job. However, you should really try to get your bags sealed as quickly as possible (within 10 minutes, 20 tops). Otherwise you risk the OA absorbing too much outside air and not being able to absorb all the oxygen in your Mylar bag.
Tip: Before you open your oxygen absorbers, mark each bag with how many OAs the bag needs. This will speed up the process.
Step 5: Fully Seal the Bag
As soon as you’ve added oxygen absorbers, you need to quickly seal the bag. Press the bags to get out as much air as you can. Then seal the remaining 2 inches.
Step 6: Checking the Seal
Wait at least one day. Then go and check on your Mylar bags. Look at the seal and see if you can squeeze any air through them.
When oxygen absorbers have done their job, the bag may look “sucked up” or vacuum-sealed. However, since so much of air is actually nitrogen, it is possible for the bag to be properly sealed but not sucked down.
Step 7: Seal Buckets or Containers
Once you are sure that the seal is good, you can close up your buckets/containers and put them for long-term storage.
Ideally you will store them in a cool place which is accessible during an emergency (for example, you wouldn’t want all your emergency food in the basement during a flood!).
Procedure Graphic (click to enlarge)
Which Mylar Bags to Use?
Aside from the brand, there are a few key considerations when choosing which Mylar bags to use: size, thickness, and whether you want zip tops.
Mylar bags come in various sizes, typically ranging from 1 pint to 6 gallons. To give you an idea, a 1-gallon Mylar bag will hold about 6-7lbs of rice. A 5-gallon Mylar bag will hold about 33lbs of rice.
That’s a lot of rice!
If you are only doing long-term food storage for your family, you probably don’t need anything larger than 1 gallon Mylar bags.
Yes, you will need more food than this – but it is probably smarter to store the food in smaller bags.
Imagine that a disaster has occurred. If you opened up a 5 gallon bag of rice, there is no way you could eat it all before the food got destroyed (by water, rodents, etc.).
Also consider how you’d use the food. Eating 6lbs worth of rice might be feasible, but 6lbs of dehydrated onions? You’d be much better off putting the dehydrated onions in a smaller bag.
The downside, of course, is that it takes more work to store food in smaller bags. You’ll also have to do a lot more planning to figure out how you’ll divide up the food.
How Much Food Will Fit in a Mylar Bag?
|Food Type||1 gallon||5 gallons|
|Whole Grain White Wheat||5-7.5lbs||25-38lbs|
|Beans (black, pinto, white, etc.)||5-7lbs||25-40lbs|
|Diced Dried Carrots||3.3lbs||16-17lbs|
*How much food you can fit in a Mylar bag depends on a lot of factors.
- How big the food you are trying to store is (for example, some beans are smaller than others).
- How well you shake the food to pack it down and how high you fill the bag. It’s easier to seal a bag which isn’t completely full.
- You’ll be able to fit more food in thinner Mylar bags because they are more flexible.
Mylar bags come in various thicknesses, with 4.3mil and 7.5mil being the most popular. The 7.5mil bags will hold up against damage better. However, they aren’t as flexible.
Because the thick bags are so much stiffer, you probably won’t be able to get as much food in them as a thinner bag.
Also note that the 7.5mil bags are sharp! You should wear gloves when working with them so you don’t slice your fingers.
Mylar Bags with Zip Tops
There are some Mylar bags which have zip tops. The zip top does NOT replace heat sealing. However, it is great for convenience.
During the sealing process, you can first squeeze the air out and zip lock it before heat sealing. It prevents little pieces of product from getting into the seal.
Once the bag is open, the zip is also great for closing the bag while you use the contents.
- Ten (10) 5-gallon Mylar bags
- 5mil thick
- Ten (10) 2000cc ShieldPro oxygen absorbers
- ShieldPro oxygen absorbers absorb 200% to 300% of their rating
- Sixty (60) 1-Gallon Mylar Bags
- 5mil thick
- Sixty (60) 300cc ShieldPro oxygen absorber packets
- ShieldPro oxygen absorbers absorb 200% to 300% of their rating
- Temperature setting of 410F is perfect for sealing Mylar bags
- Lightweight and easy to hold
- Just lock down and hold for seal
- Adjustable temperature up to 450F
- 1 inch plate
- 8 foot long cord