3rd Edition, 2012 Hank s guide to Storing Wheat in CO2 Storing Grain For those who want to store wheat for several years this article provides some guidelines for successful wheat storage. The Big 3 However you store your wheat, you ll need to do these three things: remove oxygen, maintain a low moisture level and protect it from insects and rodents. Remove Oxygen Although removing oxygen is not essential, I recommend it. Here s why. Food deteriorates faster when oxygen is present. Without oxygen, food retains its flavour and tastes nicer, longer. Weevil eggs which are present in fresh wheat will hatch into an oxygenless environment and die after hatching. Weevil will hatch then die. Low moisture level Buy wheat with a low moisture level. i.e. 10% - 12.5%. Store it in dry containers the same day you receive it. Check your containers to make sure they keep moisture out. Store in a dry cool place. Pest-Proof Containers must be mice and weevil proof. Rats and mice gnaw through many containers though plastic drums are a strong deterrent. Mice bite through vacuum-packed plastic with ease. Pack these into vermin-proof containers. Weevil photo by ken-ichi www.flickr.com/photos/ken-ichi/ CC BY-NC-SA 2.0 Oxygen can be removed by vacuum packing. Alternatively, air can be replaced with a harmless gas like nitrogen or CO2. Stored food is too expensive to feed to mice. Also, they might urinate, excrete or die on your food storage. Store it well. Get the containers first, wheat second. Mouse photo by pshab Pshab www.flickr.com/photos/pshab/ CC BY-NC 2.0
Preparation You will need: Esky or polystyrene chilli-bin 240 Space-Saver containers & lids Plastic ladle of 1 table-spoon capacity Hammer to test wheat Labels for containers ( Lid Labels and Product Labels) Get Dry Ice Collect the Dry Ice within an hour of using it. Avoid keeping it for several hours before use. Get an Esky or polystyrene chilli-bin. Go to your nearest BOC store. Buy one kg dry ice. It will cost about $15. Hammer Test Test a wheat sample for it's moisture content. This will ensure it is dry enough for long-term storage. I recommend you use the "Hammer Test." Take a spoon of wheat from your wheatsack. About twenty grains. Place them on something made of solid metal. A piece of railway line, a vice or steel anvil will do. Hit the wheat kernels once, hard, with a hammer. If the wheat shatters into pieces it is dry enough to store long-term. If it mashes or does not shatter cleanly, then there's too much moisture in your wheat for storage. Longer seeds should snap smartly, cleanly in half when bent if they are this dry. Wheat and corn seeds should shatter and powder when hit with the head of a hammer. That's our Dry Seed Test. It is very reliable. Beans, peas and other large seeds will shatter if sufficiently dry. Drive back with the window partially open so you have air flow in the car. You need to work quickly as a team before the CO2 evaporates Assign Team Member Tasks You can do this all alone but its better to get helpers and work as a team. Mormons storing wheat together is similar to the old-fashioned barn-raising of our early pioneers. We work together as a team. Assign people to the roles of a Sack-Man, Pourer, Bin-Man, and an Ice-Guy.
Train your team Teach your team the following: Warn team that dry-ice is very cold at minus 78 degrees. They must not touch it, eat it, or play with it. Read aloud the Safety Data Sheet about it.keep your hands dry when working with it. Ensure the room is ventilated and has air flow. Keep the lid on the Dry-Ice Esky as much as possible. Avoid inspecting it unnecessarily. Some dry ice will sublimate every time you open the container. Use it within hours. The sooner the better. Learn Your Duty then begin The Sack-Man will open all wheat sacks. They will also fold and stack empty sacks. Keep the area clear. The Pourer spours 4 cm wheat in the bottom of each Space-Saver in the room. This will cover the bottom of each Space-Saver. It prevents the base of the Space-Saver freezing. The Bin-Man will inspect spacesaver bins for contaminants during manufacturing process. Remove any loose pieces of plastic. Ensure each container is clean. They will supply new, empty Space-Saver Bins and to keep the Ice-Guy supplied with new bins. The Ice-Guy will use a long handled plastic ladle to deposit 10 grams (a heaped table-spoon) of dry ice into each Space-Saver on top of the small amount of wheat in the bottom centre of each 15 litre container. Note: 10 grams is about 3 pellets on a heaped table-spoon. The Pourer then immediately fills the remainder of the container with wheat from the sack. The Ice-Guy shakes down the wheat to settle it so the container can be filled to near maximum capacity. Fit the lid with one corner slightly raised so the expanding gas can bubble-off. If you seal it too soon the expanding gas might pop the lid of and spread wheat everywhere. The Sack-Man will remove the Space- Savers as they are filled with wheat and stack them at least 4 meters away so your work area is not crowded. Do not stack two layers high until after Bubble-off. Afix Labels Place labels neatly and squarely on each Space- Saver bin with the date packed and contents. Sublimation Bubble-off for 60 minutes (Sublimation) Bubble-off is the process where the dry-ice sublimates (turns from a solid to a gas) in the wheat and turns instantly from a solid to a gas. It expands to 500 times it s size in this process. Excess air will burp out of the partially closed lid. The CO2 is colder than the air in the container so it will fill up from the bottom of the container, pushing the air out. CO2 is also heavier than air. The lid should be fully covering the base yet able to allow gas under slight pressure to escape from the container so no pressure builds up. Air should not be able to get in during bubbleoff.
Allow the wheat to 'bubble off' CO2 as the dry ice sublimates. The containers will bubble out excess CO2 for 40 minutes. Vacate the room as the CO2 'bubbles off'. CO2 is not poisonous to inhale but people need to breathe in some oxygen. Ventilate the room. Anticipate children, youth or visitors entering the room overnight or in the morning. The room may be filled with CO2 if it there is no air-flow. Secure Lids Secure lids firmly 1 hour after filling the Space-Savers. Ensure they are sealed perfectly. The dry ice will have sublimated. Excess CO2 and air will have bubbledoff. Oxygen Absorbers Do not use oxygen absorbers when storing wheat in CO2. Its unneccessary. Only use oxygen absorbers when storing small quantities of wheat in vacuum packs. You will not need them at all if using dry ice as the CO2 will drive out all air including the oxygen that is in the air. About If you have additional information or wish to improve this document, please email hank.ensing@gmail.com Indemnity Clause No responsibility is taken by the author for the use of any information provided herein with regard to health and safety, food stored, loss of food, damage to food or flavour or any other aspect. Where To Get Containers Space-Saver containers are good for storing wheat. They have a 15 Litre capacity with a lid that seals. Obtain them second hand for just a few dollars each from fruit pie bakeries across New Zealand. Barkers Orchards package their processed fruit filling in Space-Saver containers and send them full to fruit pie and cake bakeries all across NZ. They ship with two types of lids. One type seals much better than the other. New containers are made by Viscount Plastics in Christchurch, Tel 64 09 276 8679, sold in bulk. www.viscountplastics.co.nz Buying new is much more expensive, however, it ensures you get the lids that seal best. I bought 12 empty containers, 2 sacks of wheat and stored the wheat using dry ice all on my own. It took me two hours. I found it easy to store the wheat alone. Hank Ensing has served as a ward welfare specialist in the Grandview Ward, Glenview New Zealand Stake and the Koromatua Ward, Temple View NZ Stake.
Check on your wheat after 1 year. Is it dry enough? If it smells like mold then feed it to the hens. If it is just damp you can dry it. Drying wheat I dried wheat on a trampoline in the sun for several hours. You can dry it on a tarp on the floor in the sun. Another way to dry wheat in in buckets with sloping glass lids. Allow a gap for the air to circulate. Stir the grain regularly. Cover with a light mesh if you want to prevent weevil from landing on it. Photo below is by Jacqui Vowles, drying her family grain in New Zealand.