Joined: Nov 25, 2006 Posts: 1468 Location: Columbia, South Carolina
Posted: Mon Jun 04, 2007 11:47 am Post subject: Absorbing Air out of Food Barrels?
I remember in another thread someone mentioned these packets of some kind to absorb air out of barrels of food (rice I believe was what was mentioned though I imagine this could be used with other grains and even dried fruit or even jerky).
Anyone know what I'm talking about? What are these called?
Posted: Mon Jun 04, 2007 12:34 pm Post subject: Re: Absorbing Air out of Food Barrels?
What you're looking for are called "oxygen abosrbers". They're a packet of chemicals that react with the oxygen in the air and chemically bind it.
They come in different sizes, depending on how big of container they're going into, and you can use several of the smaller ones in place of one big one.
Walton sells them, among others, here's a link to an explanation:
Oxygen Abserber Info
Joined: Jan 03, 2005 Posts: 1185 Location: western Wisconsin
Posted: Mon Jun 04, 2007 1:27 pm Post subject: Re: Absorbing Air out of Food Barrels?
The oxygen absorbers often work on the principle that rust is iron and oxygen--the rusting process absorbs oxygen from the atmosphere. The necessary ingredients are packaged up, put in you sealed container, and when you open it days, months, or years later, the oxygen absorber packet will be found to contain mostly good old iron oxide--rust.
Posted: Mon Jun 04, 2007 2:25 pm Post subject: Re: Absorbing Air out of Food Barrels?
Some other thoughts on storage...
I've mentioned before using Carbon Dioxide for grain storage. Walmarts that sell CO2 ice also have pamphlets that mention that use. CO2 is great for killing bugs that might be in with your grains. Also, burning a tea light or incense in your storage container might work, but that is a more wild idea. And I know that grains can be smoked, like meat... But anyway, if removing oxygen to kill bugs is your plan, Carbon Dioxide is cheap and easy to use for that purpose. And may be a cheaper solution then "oxygen absorbers".
If you want to remove moisture, as mentioned there are lots of good desiccants on the market and they're relatively cheap. I picked some up at an antique show a month ago, you can find them in a lot of places.
Joined: Oct 04, 2004 Posts: 5440 Location: Oklahoma
Posted: Mon Jun 04, 2007 3:59 pm Post subject: Re: Absorbing Air out of Food Barrels?
Dessicant is available in big containers quite cheaply at hobby shops because people use it for drying flowers. _________________ "Every junkie's like a setting sun..." - Neil Young
Posted: Mon Jun 04, 2007 5:05 pm Post subject: Re: Absorbing Air out of Food Barrels?
{Edit} Fixed grammar/ run-on sentances
Most dessicants will not remove the oxygen, they will only remove moisture in the air.
As posted above a metal that oxidizes will remove oxygen provided the container is sealed.
Dry Ice will displace the oxygen as it is more dense. I'm not sure of the proceedure as I don' t think you would want to seal the crate until the dry ice is completely a gas. You would get a higher CO2/O2 ratio if you allowed the oxygen to escape.
Also you would run the risk of building up pressure and popping your vessel.
However, if you didn't seal the vessel, the dry ice could condense moisture from the air adding water to your container.
Maybe the best would be to add dessicant, add CO2 allow the CO2 to sublime (don't put your head in the vessel as it will be an oxygen deficient environment), and then seal.
Last edited by pjd2 on Mon Jun 04, 2007 5:17 pm; edited 1 time in total
Joined: Oct 04, 2004 Posts: 5440 Location: Oklahoma
Posted: Mon Jun 04, 2007 5:07 pm Post subject: Re: Absorbing Air out of Food Barrels?
That's right, pjd2, dessicants remove moisture, not oxygen. However they are useful for various things, so I posted the info here in case anyone could use it. _________________ "Every junkie's like a setting sun..." - Neil Young
Posted: Tue Jun 05, 2007 9:12 am Post subject: Re: Absorbing Air out of Food Barrels?
pjd2 wrote:
Also you would run the risk of building up pressure and popping your vessel.
The common solution is to wait 12 hours for the CO2 to diffuse though the grain being stored and then tighten down the seal. But gluing a fishtank one way valve to your container top would be another solution.
pjd2 wrote:
However, if you didn't seal the vessel, the dry ice could condense moisture from the air adding water to your container.
You aren't really adding moisture. But if you think condensation could be a concern for what you are storing, there are different ways to deal with potential condensation. Such as wrapping the dry ice in paper towels so it warms slowly and dissipates slowly to avoid condensation.
Condensation isn't a usually problem because the dry ice is at the bottom of a pile of grain and pushing air away from it, so water from the air is not in contact with the dry ice. Also if speed is important, filling the container with warmed carbon dioxide from a cylinder or a cylinder of nitrogen can be faster. But in that case you may need to add a valve to the bottom of your container for introducing the gas and a valve at the top for releasing excess. Or do some fancy things with tubing... But all that shouldn't be necessary.
Some quotes and links on storage
Quote:
Factor #3: Atmosphere the product is stored in:
Foods packed in air don't store as well as in oxygen free gasses. This is because air contains oxygen which oxidizes many of the compounds in food. Bacteria, one of several agents which make food go rancid also needs oxygen to grow. Food storage companies have a couple of different processes for removing the oxygen:
* Displacing the oxygen: This is done by purging out all the air in the product with an inert gas. Nitrogen is almost always used because it is the most inert gas known. People doing their own packing occasionally use dry ice which gives off carbon dioxide gas, and probably works just about as well.
* Absorb the oxygen: Oxygen absorber packets do just that. Air contains about 78% nitrogen and 21% oxygen, leaving about 1% for the other gasses. If the oxygen is absorbed, what remains is 99% pure nitrogen in a partial vacuum.
If oxygen absorber packets are used, care must be taken to use a storage container that can stand some vacuum. If it's not air tight, air will be sucked into your container as the oxygen is absorbed, reintroducing more oxygen that must be absorbed. Before long, the oxygen absorbers will have absorbed all the oxygen they can. Obviously, your product won't be oxygen free under these circumstances.
Seeds store better in nitrogen. On the other hand, seeds you plan on sprouting, such as garden seed, or seeds set aside for growing your own sprouts store better in air. For this reason Walton cans their garden seed packs in air.
Oxygen absorbers also contain a minute amount of moisture to activate the absorber. Sometimes, with the heat generated by the absorber, they can cause sweating if you use glass bottles or tupperware type containers.
Factor #4: The container the product is stored in:
To get the best storage life out of your product it must have a hermetic (air tight) seal. Containers that do this well are:
* #10 Cans (Use only cans that are enamel lined, otherwise your food flavor will be tainted by the steel it comes in contact with. An enamel lined can also prevents the inside of the can from rusting.)
* Sealable food storage buckets
* Sealable food quality metal (lined) or plastic drums.
http://waltonfeed.com/grain/life.html
Quote:
If storing large containers:
* Get air tight containers. Plastic containers encourage more condensation inside than metal. Drier is better; use enamel lined metal if you can.
* CO2 / dry ice treatment. Removes oxygen the critters need to live. Using heavy gloves, place several ounces of dry ice in the bottom of the container, slowly pour the grain on top of it. Do NOT use larger amounts of dry ice. Let stand covered, BUT NOT SEALED without disturbing for 12 hours. The air in the can is driven out by the CO2 gas which fills the container from the bottom. After 12 hours, seal the container, but check every 12 hours for any signs of pressure. If the CO2 continues to dissolve, it can push the top off or blow out the sides! Vent any excess pressure, then reseal the container.
* Silica gel treatment. Keeps the grain too dry to support bug life. Get the 40 gram tins, keep in an airtight container, change every 4-6 weeks, silica gel can be redried in a slow oven.
* Diatomaceous earth (DE). This is NOT the stuff people put in swimming pool filters. Edible diatomaceous earth is a natural combination of silica and trace minerals which has not been heat treated and is available from survivalists via the internet. It acts by drying out insects and eggs so they die. It is not poisonous, or can be washed off whole grains. Don't breath the dust, however; it can be drying and irritating to the lungs. To use DE, mix 1 ounce (2 teaspoons) mixed into a five pound jar of grains. Mix 1 pound (just under 3/4 cup) in each 100 pounds of grains.
http://www.ellenskitchen.com/pantry/storage1.html
Quote:
CO2 and Nitrogen
Carbon dioxide (CO2) and nitrogen (N2) are commonly used in packaging both fresh and shelf-stable foods, in order to extend their usable shelf lives. Fresh foods are outside the scope of this work so attention shall be focused only on those foods suitable for use in storage programs.
In order for either gas to be used most effectively to gain the longest possible shelf life it is recommended that it be contained inside of packaging with high barrier properties to prevent it from diffusing out over time or allowing oxygen to infuse in. Examples of this kind of packaging are Mylar and other high barrier property plastics, metal cans and glass jars. Buckets made of HDPE plastic are relatively poor gas barriers and will, over time, allow oxygen to infuse into the container. In order for foods to be kept for their maximum shelf lives the containers would need to be re-purged every three to four years.
http://waltonfeed.com/grain/faqs/ivb.html
Quote:
Vacuum Sealers
Vacuum packing is a very simple concept. Lower the air pressure (22 inches of vacuum or more) in a container until sufficient oxygen laden air has been removed to slow the development of rancidity and retard the growth of insects. Within reason, the greater the amount of air removed the better the process will work.
http://waltonfeed.com/grain/faqs/vacuum.html
Most storage methods like these suggest regassing your grains after 4 years and or using them... But theoretically, if you wanted to extend your storage time beyond 4 years you could probably do that using a combination of techniques. Such as Dry ice on the bottom, desiccants and a vacuum sealer. But I think that would be overkill...
Posted: Tue Jun 05, 2007 9:51 am Post subject: Re: Absorbing Air out of Food Barrels?
Thanks Steam Cannon for filling in the gaps.
That info is very good to know.
I was just worried about condensation because whenever we use dry ice in our lab, it will leave behind a a major puddle of water on a humid day.
I also know that we occassionally use carbonic bases (cesium carbonate, potassium carbonate etc.) as desicants. I wonder if people could use something like sun/flame dried and crushed limestone (mostly cesium carbonate) as a dessicant if necessary. This might be usefull if silica gel or other desicants are unavailible in significant amounts. Does anybody have information on this?
Posted: Tue Jun 05, 2007 3:45 pm Post subject: Re: Absorbing Air out of Food Barrels?
pjd2 wrote:
I wonder if people could use something like sun/flame dried and crushed limestone (mostly cesium carbonate) as a desiccant if necessary. This might be useful if silica gel or other desiccants are unavailable in significant amounts. Does anybody have information on this?
There are a lot of things that would probably work. Here are two ideas that would be easy to test...
Dry Clay and Wood Ash Desiccants
Desiccant Types
Clay is a good basic desiccant that works satisfactorily below 120°F ... The upside to clay is that it is normally the least expensive desiccant per pound.
http://www.sorbentsystems.com/desiccants_types.html
Thanks all, what method do you guys personally use (assuming you got some long term storage)?
My experience with storage mostly is from working with my Dad coming up with a storage solution where he works. The vitamin supliment regulations for Europe require not using most preservatives, so how do you store factory volumes of dry edible powders without preservatives? Carbon Dioxide or nitrogen, just like in grain storage...
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