Information on how to preserve grains with dry ice.

Oxygen absorbers may be easier to use for grain storage, but I prefer using dry ice (frozen carbon dioxide) to store my grains. The dry ice method is much cheaper, and because it is a fumigant it actively kills the insects that may already be in the grains.

NOTE: The eggs of the insects are in all wheat and under the proper circumstances (time, humidity and warmth) they will hatch. They bore into the wheat kernel from end to end, eating the center of the kernel. The remaining outer part will begin to crumble and form a fine powder. You can't glance into a full bucket of wheat and tell if there are bugs in it unless the problem is severe.

The best way to avoid an insect infestation is to purchase from suppliers who are clean and have a high quality products. This will mean the products you purchase will be less likely to have bugs in them.

When you buy grains take a close look to be sure that insect are not visable. Don't shake the grains because most adult insects will be visible in the top couple of inches of the grains and shaking the grains could mix them further sown into the container where they will be less visable. If the grains you pruchased do have bugs take them back and replace them.

The good news about dry ice is that it takes as little as 10% carbon dioxide over a fairly short period of time to kill insects. At 10% the insects would be killed in about a month. The higher the concentration of carbon dioxide, the faster it kills the insects. The time it actually takes can be reduced to hours rather than weeks at close to 100% concentrations. It is easier to get enough carbon dioxide into a container of grains to kill the insects than it is to get 100% of the oxygen out, and then keep it out.

Important Information !

All you need is a bucket with a lid that will make an airtight seal and a little dry ice. Dry ice is a solid and looks much like regular ice - except that it's -110 degrees F. below zero (-78.5C).

DRY ICE SAFETY: Never handle dry ice with your bare hands, it can cause severe burns! Always use gloves or tongs. If using large amounts of dry ice indoors or in a closed area allow for plenty of ventilation. As it sublimates the dry ice releases it's carbon dioxide which living creatures, like us, shouldn't breath. Do not store Dry Ice in an air-tight container without proper ventilation, the carbon dioxide gas will cause any airtight container to explode.

IMPORTANT NOTE: When you store your food in plastic pails, make sure they are food-grade. Other plastics are made with chemicals that are not good for your health and leech out into your stored food.

Dry ice is frozen carbon dioxide. Carbon dioxide is a fairly harmless gas as long as it doesn't deplete all the oxygen in the air you are breathing. Unless you will be packaging your grains in a very small airtight room, you should have nothing to worry about. But be aware that under unusual circumstances carbon dioxide can be deadly. I've had several people send me emails about a person who actually died while using dry ice in a haunted house at Halloween. Apparently, the person was under a card table covered with a blanket, using water and dry ice to make a thick cloud. They said it didn't take an airtight closet to kill him. Counter this with the news story of the woman who put a whole tub of dry ice under her husband's bed trying to 'do him in.' When she was arrested for attempted murder she said, "I don't understand, it worked on Matlock!"

We breath in air containing oxygen and breath out air containing carbon dioxide. There's carbon dioxide in our houses all the time simply because we are breathing. I've heard people say you have to do this outside or the
fumes will get you. That's the reason I'm making such a big deal out of this. Just use common sense.

Carbon dioxide, in it's frozen form, is highly compressed compared to it's gaseous state. A pound of it contains enough carbon dioxide gas to make 8.3 cubic feet of carbon dioxide gas. A six gallon bucket contains 1.46 cubic
feet of space. Fill the bucket full of beans or wheat and you have about 0.48 cubic feet of air left in the container surrounding your food. So, if you use twice as much dry ice as you actually need to displace the air in the bucket, you will need about .06 lbs, or right at one ounce of dry ice. Heck, be generous and put in two ounces of dry ice if you like. The smallest amount of dry ice I can purchase is 5 lbs which costs me $5.00. At even 2 ounces per bucket, that's enough dry ice to take care of preserving 40 buckets of food, more than I have ever done at one time. At two ounces per bucket, this is enough dry ice to push the air out of a six gallon bucket four times. You want a little bit of overkill or redundancy here as it's always better to overdo this than under-do it and end up with oxygen left in the container.

Where To Get Dry Ice.

I get all my dry ice from a welding supply shop. It's also often available at ice cream places and chemical supply houses. When you get your dry ice you need to bring your own container to put it in. There is one thing you really need to watch for if you are going to be using dry ice to preserve your foods. You must prevent water vapor from freezing on the outside of the dry ice. This moisture would later melt off the dry ice in the bottom of your bucket and increase the water content of your grains. As you don't often have a lot of room to play with as far as water content is concerned, it is important to ensure you don't add any moisture to your product with your dry ice. The dry ice you buy from the store should be water free, and that's the way you want to keep it.

Dry ice is always giving off carbon dioxide gas, so it's relatively easy to keep the water moisture from it. Just be sure you don't put it into a container that breaths, like a paper bag or cardboard box. I use a Tupperware container which has its own lid. This container is just right because its lid is tight enough to keep water vapor from the ambient air out, but loose enough to permit the carbon dioxide gas to escape as it sublimates. By the time you get it home, there will be a thick layer of frost on the outside of the container - exactly where you want it, on the outside - not the inside. The inside will be moisture free because of the continually escaping carbon dioxide gas.

There was one time I purchased dry ice which had a bunch of water crystals mixed in with it. You can tell this because there is a white powder mixed in with the dry ice cubes. Ice is just a tiny bit whiter than the light blue
dry ice. You can put a teaspoon or two of this powder in a bowl, wrap plastic wrap around the top, and wait for it to turn into a gas. If it's indeed water, when it melts you will get a little liquid in the bottom of your bowl. If it was dry ice, the bowl will be dry.

You can use dry ice with all grains. At home I use dry ice to preserve all my seeds, and all my grains and legumes.

Before you ever buy it, plan on having your packing operation complete 5-6 hours after you've purchased the dry ice. Otherwise, it may 'sublimate' away on you until it's gone whether you are finished packing your buckets or not.

So, how do you do it?

Materials Needed: A food scale, a measuring cup, dry ice, the grains you are planning on preserving, and storage containers.

The process: Zero your food scale with the measuring cup sitting on top of it. Open the container with your dry ice in it and take out about 1/3 cup and measure it. Depending on how your dry ice cubes are shaped, you should have about 2 ounces. (Remember, if you want to be stingy, one ounce will do the trick, that's 28.5 grams.) Pour this into the bottom of the bucket in a neat little pile and place a paper towel over the top. Why the paper towel? It keeps the dry ice away from the food, not that it's that important. Now place your grains inside the bucket, filling the bucket up to within a 1/2 inch of the top. Set the lid lightly on top and wait. Recently, I have been sealing the lid all the way around except for one small side.

You DO NOT want to seal the lid completely as the carbon dioxide and air must have a place to escape. If the lid makes an airtight seal, the expanding carbon dioxide inside the bucket will continue to increase in pressure until something gives - either the lid will pop off or the bucket will split. Either way you are going to have food all over the place when this thing goes off. How do you know when all the dry ice is gone and it's
safe to seal the lid? Simply pick up the bucket and feel the bottom. If it is still icy cold there's still dry ice in the bottom. You may need to be a little patient here. My experience has been that it takes 1 to 2 hours for
all the dry ice to change into a gas. I've had others E-mail me saying they had to wait around for 5-6 hours! So you may wish to plan in a certain amount of time for this in case it takes a while. You want to seal the lid just as soon as this has happened, however, because if you don't, air will start circulating back into the container.

After 15 or 20 minutes, I start checking my buckets, and then recheck them every ten minutes or so. After you seal your buckets, it's always a good idea to keep an eye on the lids for the next hour or so. The lids will start bulging up if you sealed them a bit prematurely. If this happens, use a bucket lid remover to crack open the lid on one side to let the excess gas escape, then seal the lid back down. I'm not sure why, as my logical brain tells me it should be otherwise, but over the next several days there will usually be a small vacuum created inside the bucket and the side will pop in a little bit. Don't concern yourself with this. Your bucket will store just fine.

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