About using CO2 for purging oxygen from containers

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I'm about ready to 'bucket up' some grain & pasta using the CO2 method to purge the oxygen from the container.

What, if anything, do I put between the dry ice and the product in the bucket? Should I be concerned that the cold will damage either the bucket or the product?

The rest of the process I understand, just this one little point.

Thanks - and take a minute to ready Cory's Weather Report # 100.

-- JD (sandpine@juno.com), November 04, 1998


According to


"Using dry ice to displace oxygen from food storage containers is a very straightforward affair. To prevent leaching plastic chemicals from the container into your food over a long period of time I recommend lining the bucket with a food grade plastic, mylar or brown paper bag before filling the bucket with your product. Be sure to wipe any accumulated frost off of the ice and wrap it in a paper towel or something similar so 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. One pound of dry ice will produce 8.3 cubic feet of carbon dioxide gas so about four ounces 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.

WARNING: Dry ice (frozen carbon dioxide) is extremely cold and can cause burns to the skin by merely touching it. Because of this you should wear gloves whenever handling it. Also, dry ice evaporates into carbon dioxide gas, which is why we want it. CO2 is not inherently dangerous, but you should make sure the area you are packing your storage containers in is adequately ventilated so the escaping gas will not build to a level dangerous enough to asphyxiate you.

IMPORTANT NOTE: Because dry ice is very cold, if there is much moisture in the air trapped in the container with it, and your food, it will condense. If there's enough of it, it's going to cause you problems. Try to pack your containers on a day when the relative humidity is low or in an area with low humidity, such as in an air- conditioned house. Use of a desiccant package when using dry ice to purge storage containers is a good idea.

Dry ice may be found at ice houses, welding supply shops, some ice cream stores, meat packers or you could look in your local phone book under the headings "dry ice" or "gasses". "

Hope this helps

-- rocky (rknolls@hotmail.com), November 04, 1998.

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