MOLT (Moisture, Oxygen, Temperature, Light) - The Enemies of Long Term Food Storage

Posted by Tobias Truman on 9th Apr 2014

One of the most frequent emergency preparedness questions I get asked is 'how long will food store?' if I use Mylar Bags and Oxygen Absorbers. I don’t try to be evasive, but sometimes I can’t come right out and say a specific period of time, whether that will be 1, 5, 10, 20 or even 30 years, which is the claim that many survival and preparedness sites use as the longest food will store. The reason is that there are multiple factors that go into whether your food will store poorly or well long term, and the packaging is just one piece of it. I definitely don’t want my families livelihood or another families survival threatened if I say ‘yes, your food will store 5 years’ and then 5 years from now someone opens their food and find it is spoiled because they stored it in their garage which is 110 degrees in the summer and -10 in the winter, they didn’t seal the bags properly, and they stored food with 25% moisture content.

Here is what I will say: there have been studies of long term food storage methods done by the LDS and others that indicate some foods can be stored up to 30 years or more. What that means is that the food retains its nutritional and caloric value, but might still have some taste and palatability issues. However, please be aware that most of these studies are for the standard practice of the LDS Church of using #10 cans in their food storage. You might find it funny for a supplier of Mylar and O2 absorbers to recommend #10 can sealing. Mostly I want to provide the best information I can, and there is no doubt that #10 can sealing is the best way to store food long term…if you have access to a sealer and a supply of #10 cans. The challenge is can sealing is VERY expensive. To store the same 400 pounds of food that a standard Mylar Bag combo kit can, it would take approximately 80 #10 cans. Even if you add in the cost of buckets, it would cost the average person $80.00 or so to store using Mylar and buckets, but over $400 using #10 cans. That’s a pretty huge difference if you are trying to take care of your financial resources. If you have access to an LDS cannery, you can get cans much cheaper, but even so it would cost 50-100% more to store using cans.

So yes, I recommend #10 can sealing if you can afford it and have access to the tools needed, but I recommend Mylar and bucket storage as the next best thing for the rest of us preppers. A properly sealed Mylar bag stored with an oxygen absorber inside a bucket mimics the most important properties of the #10 can system: oxygen elimination and light control inside a rigid barrier to protect from rodents or insects. The other two properties that most effect your long-term food storage and temperature and moisture.

Because I had a hard time remembering the four main enemies of food storage, I came up with the acronym MOLT. It stands for Moisture, Oxygen, Light and Temperature, and it helps me keep focused on mitigating each of them when our family stores food. Sometimes I include ‘Time’ as a fifth enemy, but it is really just that the other 4 do damage…over time. Let’s take a brief look at each.

Moisture is probably the most difficult of the factors affecting your food storage, mainly because it is a byproduct of our environment and where we live, as well as a component of the actual food. Unless you live in a desert or extremely arid part of the country, you are going to have some or much humidity at one or more points during the year. This is also why you should look to store low moisture foods, preferably under 10%. It’s interesting that many types of dog food will list the moisture content right on the bag (we have several between 8-12% moisture stored), but people food generally won’t. This is likely a combination of lack of interest, lack of regulation, and the fact that people foods are almost always listed with a shelf life. The food types that are available with a low moisture content are those people generally associate with long-term food storage: grains, beans, legumes, and dehydrated or freeze dried foods. If you are buying bulk grain from a farmer, they will usually know the moisture content of their products; some bulk packaged foods at the big box stores may also indicate it on their packaging. A good rule of thumb is grains will shatter and turn to powder if hit with a hard object; other seeds should break in half if bent. This is another case of using your best judgment.

The second enemy of food storage is oxygen. Oxygen allows the growth of micro-organisms, some of which can be harmful to food, as well as causing oxidation (especially profound on oils, which become rancid) and spoilage. Luckily, with the development of oxygen absorbers, it has become fairly easy to eliminate oxygen inside food packaging. Mylar bags meant for food storage have incredibly low oxygen (and water vapor) pass through. For example, the larger Mylar bags we carry have an Oxygen Transfer Rate (OTR) of less than 1cc (1/1000th of a liter) per year. So if you stored a bag of wheat long-term and it was properly sealed with an oxygen absorber, it would take 1000 years to have 1 liter of oxygen pass through the bag. That’s quite a barrier!

Light is the third enemy of food storage. This, combined with the others, is why it is always recommended that you store food in a ‘cool, dark, and dry’ place. Like oxygen, light causes spoilage and the reduction in vitamin content in food. However, it is probably the easiest characteristic to guard against. Mylar itself is an excellent light barrier; a bucket is another. Storing food in a dark area completes the process. Even most standard food packaging blocks light sufficiently. I suggest this is probably the easiest of the 4 enemies to fight.

The final enemy of food storage is temperature. Depending on where and how you live, it may be easy or extremely difficult to control the temperature at which you keep your food storage foods. In the old days, many people had root cellars to help preserve food. Today, if you have a basement, it may stay relatively cool as well. We are lucky in that we have a split-level ranch where our downstairs/basement stays on average 10 degrees cooler than upstairs. This allows our food storage to stay in relatively decent condition of around 50-60 degrees year-round. However, during the height of summer it can get to 70 degrees, depending on how much we use our basement door for outside access. One rule of thumb is that for every 10 degrees warmer it gets, your foods’ shelf-life is cut in half. For example, if you go from storing a bucket of wheat at 60 degrees to 70 degrees, instead of lasting 20 years, it will likely only last 10. You can see how important this makes the environment you are storing your food in. I’ve seen some great suggestions for storing food in a regular living area to take advantage of the generally cooler environment. For example, some folks store food in closets or under their beds. You can find wheeled shelving that will even let you put canned goods under a bed and be able to roll it in and out for access.

As you examine your situation, take some time to plan when you are about to begin a phase of food storage. Understand the environment you have to work with, and consider buying foods appropriate to that environment. If you live in area where humidity is high year-round, consider more canned goods than others which will degrade because of that. If temperature is an issue, be prepared to rotate your foods more frequently.  Your survival may ultimately depend on your ability to plan.

As always, if you have any questions, please drop me a line at!