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Storing Grains and Legumes
By Alan T. Hagan
Moisture and Desiccants
The key to storing grains (and legumes) for the long term is dry, dry, dry. Available oxygen and storage temperature also play roles, but it is moisture content that will determine whether you get usable food out in five years or not.
Therefore, the idea here is to have the food that you want to put into storage as dry as possible before it goes in and then take steps to deal with any moisture that may be trapped, generated or leaked into your storage containers.
Ideally, the clean grains and legumes that you have in hand will be no more than 10% moisture. If this is the case then you can go ahead and seal them into your storage containers using the packaging method of your choice and have a reasonable expectation of your food staying in good condition.
If your storage grains aren't sufficiently low in moisture content then you'll need to reduce the water that they contain. Wheat has been taken out of Egyptian pyramids where it had lain for several thousand years. It was the bone dry desert air and the cool interior temperature of the pyramids that kept it from rotting away. We can approximate that Egyptian climate by several methods.
The least involved method is to wait until the driest time of year for your location. I typically wait until January here in Florida. If this doesn't suit, then turn your air conditioning on a little high. Bring in your buckets, lids, and the storage food. Let everything sit in a well-ventilated place where it's going to get plenty of cool from the a/c. I'd avoid anywhere near the kitchen or bathroom areas, as they put out a lot of moisture. About three days of cool, constant air flow and low humidity ought to dry things out a bit.
If this won't do, you can place a large quantity of desiccant in your storage containers. Fill the remaining space with your food product and seal on the lid. After about a week, unseal and check the desiccant. If it's saturated, change it out with dry and reseal. Continue to do this until the contents are sufficiently dry. If it doesn't become saturated the first time, change it anyway before sealing the bucket permanently. You'd hate to find later that it saturated in storage.
I use silica gel for practically everything. Keep in mind that it is not edible and you don't want it getting mixed into your food. My usual procedure is to save or scrounge clear plastic pill bottles such as 500ct aspirin bottles. Fill the bottle with the desiccant (remember to dry the gel first) and then use a double thickness of coffee filter paper carefully and securely tied around the neck of the bottle to keep any of it from leaking out. This way whatever moisture does inadvertently get trapped inside can be safely absorbed. It won't dry out a lot of moisture -- you still need to take steps to get everything as dry as possible before you pack it -- but it will take care of what little is left.
Once you've dealt with the moisture problem, then you can decide whether you want to displace and/or absorb the oxygen out of your storage container. There are three common methods of doing this. The first two use relatively inert gasses, carbon dioxide and nitrogen, to displace the oxygen. The third uses an oxygen-absorbing chemical to remove very nearly all of the gas from the container's atmosphere. Some folks even go so far as to use inert gas displacement and oxygen absorption together.
Dry Ice
Now go ahead and pack your buckets. If you're using dry ice be sure to wipe off any accumulated frost and wrap the ice in a paper towel or something similar so that you don't burn anything that comes into contact with it. Put the dry ice at the bottom and fill the container. Shake or vibrate it to get as much density in the packing as possible and to exclude as much air as you can. Put the lid on, but do not fully seal it. You want air to be able to escape. Ideally, the dry ice should slowly evaporate and the cool CO2 should fill the bottom of the bucket, displacing the warmer, lighter atmosphere and pushing it out the top of the container. About four ounces of dry ice per five gallon bucket is plenty. Do not move or shake the bucket while the dry ice is sublimating. You want to keep mixing and turbulence to a minimum. After about three hours go ahead and seal the lids, but check on them every fifteen minutes or so for an hour to be certain that you're not getting a pressure build up. If you don't have to let any gas off, then put them away. A little positive pressure inside the bucket is a good thing, but don't allow it to bulge.
Compressed CO2 or Nitrogen
Using compressed gasses calls for a slightly different technique. Bring everything inside just like above and let it dry out. You'll need some plastic bags that are a bit larger in internal volume than the bucket. Additionally, you'll need a tank of the compressed gas that you've chosen, a hose to attach to it and a length of straight copper tubing just longer than the bucket to attach to the end of the hose. Last you'll need a pack of matches, a cigarette or similar.
Line the interior of the container with the plastic bag. Fill the bucket with grain, shaking to get it as full as possible. You don't want any pockets left between the bag and the container. Once you have gotten it full to just short of not being able to put on the lid, gather the top of the bag together. Take the hose with the copper tubing on the end and insert it to the bottom taking care not to tear the bag. Close the top of the bag around it. Turn on the valve and begin to fill the bag with gas. You want to fill it slowly so that you can minimize turbulence and mixing as much as you can. I generally will just crack the valve until I can hear it begin to hiss out and then put my hand over the end of the probe to feel how fast it's coming. It'll take a little while to fill each bucket -- about five to ten minutes per. Just as with the dry ice above, the idea here is for the cool gas to displace the warmer atmosphere from the container. The bag should puff just a bit. When I think it's full I'll hold a lit match just above the bag in the air that is escaping from it. If it snuffs right out then I figure the oxygen has been displaced, I let it run for a minute longer and remove the probe. Tie the bag off and seal the bucket. Again, you want to have the bucket as full as possible so that there'll be only minimal air space.
I want to insert a caution here about packing foods with nitrogen or CO2. Either gas will do very well for oxygen displacement inside the bucket, but the technique that you use here is very important. Dry ice is extremely cold and if there is much moisture in the air that is trapped in the container with it, and your food, then it will condense. If there's enough of it, it's going to cause you problems. If you are going to put the dry ice in the bucket, you'll really want to do this on a day when the humidity is very low. The temperature of the gas coming out of the tank has concerned me, also, since it is rather cold. I like to use as long a hose as I can get to allow the gas to expand and warm as much as possible before it goes into the bucket. An idea that I've had, but have not yet tried is to hook the hose to a copper coil (a la a moonshine still) and have the gas go through that to warm it before putting it into the container. The next time we do any experimentation with this stuff I think I will. Whether you use dry ice or compressed gas, I would add about four ounces of desiccant to a five gallon bucket of stored food.
Oxygen Absorption Packets
If all of this messing about with gasses sounds like too much trouble, you can try using the oxygen absorption packets that have come onto the market in the last ten years or so. The only brand that I am aware of is the Mitsubishi Ageless 300 (mine are the 300E type). Each unexposed tablet is supposed to absorb 300 ml of oxygen per packet, though the paper in the specific equipment section seems to suggest that they'll do much better than that. As a general rule of thumb, one packet per gallon of volume in the storage container is what is called for. Follow the directions concerning moisture and when things are dry enough then fill the containers, place one packet per gallon of container volume inside and seal it up. Be certain that you do, in fact, have an air tight seal or you'll just deplete your packets over time to no positive effect.
For those belt and suspender types who like to have as much certainty as they can get, you can use either of the above atmospheric displacement techniques and an O2 absorber packet together to eliminate all of the oxygen that you can.
Once I started using the method above with the drying out of the containers and foodstuffs, the careful atmospheric displacement with inert gasses and the desiccant, I've never lost a container of storage goods due to mold or mildew. If you've done a proper job with the gasses, you'll kill any insects or insect eggs as well. After that, it's just age and average storage temperatures that degrade the nutritional contents of the foods and you should have a rotation plan to deal with that before it becomes a problem. Take care in your technique, use only quality goods and you'll have food that you can eat when you open those containers.
Copyright 1996 Alan T. Hagan. All rights reserved
By Alan T. Hagan
Moisture and Desiccants
The key to storing grains (and legumes) for the long term is dry, dry, dry. Available oxygen and storage temperature also play roles, but it is moisture content that will determine whether you get usable food out in five years or not.
Therefore, the idea here is to have the food that you want to put into storage as dry as possible before it goes in and then take steps to deal with any moisture that may be trapped, generated or leaked into your storage containers.
Ideally, the clean grains and legumes that you have in hand will be no more than 10% moisture. If this is the case then you can go ahead and seal them into your storage containers using the packaging method of your choice and have a reasonable expectation of your food staying in good condition.
If your storage grains aren't sufficiently low in moisture content then you'll need to reduce the water that they contain. Wheat has been taken out of Egyptian pyramids where it had lain for several thousand years. It was the bone dry desert air and the cool interior temperature of the pyramids that kept it from rotting away. We can approximate that Egyptian climate by several methods.
The least involved method is to wait until the driest time of year for your location. I typically wait until January here in Florida. If this doesn't suit, then turn your air conditioning on a little high. Bring in your buckets, lids, and the storage food. Let everything sit in a well-ventilated place where it's going to get plenty of cool from the a/c. I'd avoid anywhere near the kitchen or bathroom areas, as they put out a lot of moisture. About three days of cool, constant air flow and low humidity ought to dry things out a bit.
If this won't do, you can place a large quantity of desiccant in your storage containers. Fill the remaining space with your food product and seal on the lid. After about a week, unseal and check the desiccant. If it's saturated, change it out with dry and reseal. Continue to do this until the contents are sufficiently dry. If it doesn't become saturated the first time, change it anyway before sealing the bucket permanently. You'd hate to find later that it saturated in storage.
I use silica gel for practically everything. Keep in mind that it is not edible and you don't want it getting mixed into your food. My usual procedure is to save or scrounge clear plastic pill bottles such as 500ct aspirin bottles. Fill the bottle with the desiccant (remember to dry the gel first) and then use a double thickness of coffee filter paper carefully and securely tied around the neck of the bottle to keep any of it from leaking out. This way whatever moisture does inadvertently get trapped inside can be safely absorbed. It won't dry out a lot of moisture -- you still need to take steps to get everything as dry as possible before you pack it -- but it will take care of what little is left.
Once you've dealt with the moisture problem, then you can decide whether you want to displace and/or absorb the oxygen out of your storage container. There are three common methods of doing this. The first two use relatively inert gasses, carbon dioxide and nitrogen, to displace the oxygen. The third uses an oxygen-absorbing chemical to remove very nearly all of the gas from the container's atmosphere. Some folks even go so far as to use inert gas displacement and oxygen absorption together.
Dry Ice
Now go ahead and pack your buckets. If you're using dry ice be sure to wipe off any accumulated frost and wrap the ice in a paper towel or something similar so that you don't burn anything that comes into contact with it. Put the dry ice at the bottom and fill the container. Shake or vibrate it to get as much density in the packing as possible and to exclude as much air as you can. Put the lid on, but do not fully seal it. You want air to be able to escape. Ideally, the dry ice should slowly evaporate and the cool CO2 should fill the bottom of the bucket, displacing the warmer, lighter atmosphere and pushing it out the top of the container. About four ounces of dry ice per five gallon bucket is plenty. Do not move or shake the bucket while the dry ice is sublimating. You want to keep mixing and turbulence to a minimum. After about three hours go ahead and seal the lids, but check on them every fifteen minutes or so for an hour to be certain that you're not getting a pressure build up. If you don't have to let any gas off, then put them away. A little positive pressure inside the bucket is a good thing, but don't allow it to bulge.
Compressed CO2 or Nitrogen
Using compressed gasses calls for a slightly different technique. Bring everything inside just like above and let it dry out. You'll need some plastic bags that are a bit larger in internal volume than the bucket. Additionally, you'll need a tank of the compressed gas that you've chosen, a hose to attach to it and a length of straight copper tubing just longer than the bucket to attach to the end of the hose. Last you'll need a pack of matches, a cigarette or similar.
Line the interior of the container with the plastic bag. Fill the bucket with grain, shaking to get it as full as possible. You don't want any pockets left between the bag and the container. Once you have gotten it full to just short of not being able to put on the lid, gather the top of the bag together. Take the hose with the copper tubing on the end and insert it to the bottom taking care not to tear the bag. Close the top of the bag around it. Turn on the valve and begin to fill the bag with gas. You want to fill it slowly so that you can minimize turbulence and mixing as much as you can. I generally will just crack the valve until I can hear it begin to hiss out and then put my hand over the end of the probe to feel how fast it's coming. It'll take a little while to fill each bucket -- about five to ten minutes per. Just as with the dry ice above, the idea here is for the cool gas to displace the warmer atmosphere from the container. The bag should puff just a bit. When I think it's full I'll hold a lit match just above the bag in the air that is escaping from it. If it snuffs right out then I figure the oxygen has been displaced, I let it run for a minute longer and remove the probe. Tie the bag off and seal the bucket. Again, you want to have the bucket as full as possible so that there'll be only minimal air space.
I want to insert a caution here about packing foods with nitrogen or CO2. Either gas will do very well for oxygen displacement inside the bucket, but the technique that you use here is very important. Dry ice is extremely cold and if there is much moisture in the air that is trapped in the container with it, and your food, then it will condense. If there's enough of it, it's going to cause you problems. If you are going to put the dry ice in the bucket, you'll really want to do this on a day when the humidity is very low. The temperature of the gas coming out of the tank has concerned me, also, since it is rather cold. I like to use as long a hose as I can get to allow the gas to expand and warm as much as possible before it goes into the bucket. An idea that I've had, but have not yet tried is to hook the hose to a copper coil (a la a moonshine still) and have the gas go through that to warm it before putting it into the container. The next time we do any experimentation with this stuff I think I will. Whether you use dry ice or compressed gas, I would add about four ounces of desiccant to a five gallon bucket of stored food.
Oxygen Absorption Packets
If all of this messing about with gasses sounds like too much trouble, you can try using the oxygen absorption packets that have come onto the market in the last ten years or so. The only brand that I am aware of is the Mitsubishi Ageless 300 (mine are the 300E type). Each unexposed tablet is supposed to absorb 300 ml of oxygen per packet, though the paper in the specific equipment section seems to suggest that they'll do much better than that. As a general rule of thumb, one packet per gallon of volume in the storage container is what is called for. Follow the directions concerning moisture and when things are dry enough then fill the containers, place one packet per gallon of container volume inside and seal it up. Be certain that you do, in fact, have an air tight seal or you'll just deplete your packets over time to no positive effect.
For those belt and suspender types who like to have as much certainty as they can get, you can use either of the above atmospheric displacement techniques and an O2 absorber packet together to eliminate all of the oxygen that you can.
Once I started using the method above with the drying out of the containers and foodstuffs, the careful atmospheric displacement with inert gasses and the desiccant, I've never lost a container of storage goods due to mold or mildew. If you've done a proper job with the gasses, you'll kill any insects or insect eggs as well. After that, it's just age and average storage temperatures that degrade the nutritional contents of the foods and you should have a rotation plan to deal with that before it becomes a problem. Take care in your technique, use only quality goods and you'll have food that you can eat when you open those containers.
Copyright 1996 Alan T. Hagan. All rights reserved
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