The shelf life of your food storage is affected by many things, perhaps most important are temperature, moisture, atmosphere, and containment.
Here’s more detail…
Temperature
Temperature greatly affects food storage life.
Based on the Q10 temperature coefficient formula ‘Rule of 10’,
For every 10 degrees C, shelf life will halve or double (hotter-cooler).
For every 18 degrees F, shelf life will halve or double (hotter-cooler).
An example of the general relationship of food storage shelf life with temperature:
Generally, stated food shelf life is referenced to room temperature, 22°C (72°F).
90°F (half the stated shelf life)
54°F (double the stated shelf life)
We learn from this how important it is to store your long-term food supplies in the coolest place possible; as in a basement, etc..
Temperature vs. Food Storage Shelf Life
Moisture Content
For long term storage, drier is better. The drier the food and the drier the environment, the longer the shelf life – to a point…
For example, grains should maintain a moisture content of 10% or less. Commercially dried foods easily achieve these levels.
Be aware of the likelihood that typical home dehydrated foods might not result in the same moisture levels as from commercially dried foods, and therefore may not last as long. As a rule of thumb, dried foods with 10% or less moisture will snap easily and are very brittle.
Unless the food is packaged in air-tight containment, then the moisture from the environment will work it’s way in over time and reduce it’s shelf life.
Atmosphere
Earth’s atmosphere contains about 78% nitrogen and 21% oxygen. Oxygen oxidizes many of the compounds in food and reduces it’s shelf life over time.
Bacteria, one of several agents which make food go rancid also needs oxygen to grow.
For maximum shelf life, foods should be stored in an oxygen free environment.
Oxygen absorbers dropped into a sealed container or a Mylar bag is common practice for long-term food storage. When the oxygen within the sealed container is absorbed, what remains is 99% pure nitrogen in a partial vacuum – a good atmospheric condition for food storage.
Note that it is important that the container you are using must be able to hold an air-tight seal over time.
Container
To get the best storage life for most food products, the product container must have a hermetic (air tight) seal, and ideally be opaque or stored away from sunlight. Common methods used include vacuum sealed bags, sealed cans or jars, sealed food storage buckets, and sealed Mylar bags.
If using 5-gallon plastic buckets, be sure that they are rated ‘food grade’. Remember that just because a bucket is HDPE #2 does not necessarily mean that it is food grade.
Safe Plastics for Food and Drink
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again, a good practical article. especially for those of us not terribly knowledgeable on this stuff.
thank you.
If you’re using mylar liners for storage, 5 gallon buckets do not have to be food grade.
Thanks for clarifying that. The Mylar itself will provide a safe barrier for the food.
So if you DO use food grade buckets, with gamma seal lids, you don’t need the mylar bags?
I’ve found the buckets and lids to be fairly inexpensive at local stores. Whereas I would have to order the bags and pay shipping, which most often doubles the cost of an item. Using a vacuum sealer and 1/2 gallon mason jars (I use smaller jars for things like dried herbs) is cost effective because you can re-use all those components hundreds of times. You might be surprised at how many dried carrots it takes to fill 1/2 gallon jars. Nearly 10 pounds.
Since the jars are clear, I store them in my dark and chilly pantry.
So if you DO use food grade buckets, with gamma seal lids, you don’t need the mylar bags?
Not necessarily. But…
For long term storage with oxygen absorbers I would not rely upon the gamma seal alone. I am doubtful that it would truly hold an air-tight seal for years – but I cannot prove it because I don’t take the risk. I happen to use all food-grade buckets, regardless of Mylar inserts or not, and all of my buckets have gamma seal lids.
The reason is this…
When I’m looking at my literal survival versus a few dollars more of currency for each bucket (with a gamma lid and Mylar bags with oxygen absorbers), it is worth it to me to spend the extra currency.
Also, the convenience of having each bucket ready-to-go with a gamma ‘screw-top’ lid is ideal (for later). When it comes time to use the stored food from the bucket, I would simply remove the Mylar bag and dump the ingredients back into the bucket it was originally stored in. That way I can easily access it until gone with the sealable srcew-on gamma lid, while the lid itself will prolong the shelf life until all of the food is used up.
I realize that it is not absolutely necessary though (all food-grade buckets while using Mylar bags, plus all gamma-seal lids), but I am of the personality to often err on the side of caution while willing to spend a bit extra for that peace of mind 😉
Great info!
Thank you for clarifying this for all people that went on this website.
God bless you.
am also appriciate this practical articles
Wonderful information. We are new at all this storage (food) and getting survival ready. Thanks for the info.