You should use food grade containers for storing anything you intend to eat. A food grade container is one that will not transfer non-food chemicals into the food and contains no chemicals which would be hazardous to human health. If you are uncertain whether a container is food-grade or not, then contact the manufacturer and ask if a container is approved for food use. Many manufacturers are beginning to indicate on the container label if it is approved for food use.
WHAT MAKES A PLASTIC CONTAINER “FOOD GRADE”?
Plastic films and containers of food grade quality are made from polycarbonate, polyester or polyethylene. Their characteristics in terms of density, permeability and strength vary. To limit permeability to moisture and oxygen, films of the above plastics are sometimes laminated together, frequently with a metallic layer. Military food packaged in just such a metallized polyester, polyethylene wrap has a long shelf life (5+ years) if kept cool.
The metal cans used by the canning industry for wet-pack canning are designed to last only a few years. Most losses of canned foods occur due to the breakdown of the can rather than extensive deterioration of the food under normal storage conditions.
The major disadvantages of metal cans for putting up your own food are that the cans are hard to come by, they take specialized equipment to use (but so do glass jars) and they can only be used once to seal in food. Not being reusable is the flaw that has largely made them unpopular for home canning use. Since they’re not interested in reusing the containers, metal cans make great sense for the commercial canning industry. The cans are both cheaper (for them) and lighter than glass jars and this adds to the economy of scale that makes canned foods as cheap as they are in the grocery store.
For home canners, glass jars are better because even the smallest of towns will usually have at least one store that carries pressure and boiling water canners along with jars, rings and lids. With tin cans, however, a can sealer is necessary and that usually must be ordered from its manufacturer.
Tin cans are not really made of tin. They’re steel cans with a tin coating on the inside and outside. Some kinds of strongly colored acidic foods will fade in color from long exposure to tin so a type of enamel liner called “R-enamel” is used to stop this.
Certain other kinds of food that are high in sulfur or that are close to neutral in pH will also discolor from prolonged contact with tin. For those foods, cans with “C-enamel” are used.
Compared to metal cans, glass jars are very stable, although they don’t take being banged around very well. The cardboard boxes the jars come in are well designed to cushion them from shocks. The box also has the added bonus of keeping out damaging light.
The major advantage of glass jars is that they are reusable, both jars and rings, with lids being the only part of the package that must be purchased new for every use. If you’re not using the lids to form a vacuum seal such as would happen when doing boiling water or pressure canning, then even the lids can be reused.
Now, from a strictly financial standpoint, if you take into consideration the cost of equipment including jars, rings, lids and all the rest…not to mention your time, it’s probably not cost efficient to put up your own foods. So why would you bother? Well, first, for many people, gardening is a pleasure and you must do something with the food you’ve grown! There’s also the fact that you simply cannot buy the quality of the food you can put up for yourself. The canning industry tries to appeal to a broad spectrum of the public while you can put up food to your own family’s specific tastes. Home canning is not so much about saving money as it is about satisfaction. You get what you pay for.
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 line 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 from the ice and wrap it in a paper towel or something similar so you don’t burn anything that encounters 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.
WHAT IS AN OXYGEN ABSORBER?
If all of this messing about with dry ice sounds like too much trouble (you probably know me well enough by now to know I don’t like using it), you can try using oxygen absorption packets. I don’t know exactly when they first showed up on the market for use by private individuals, but they are a relatively recent tool for long term food storage. The packets absorb free oxygen from the air around them and chemically bind it. This removes it from being available for other purposes such as oxidative rancidity and respiration by insects or bacteria. The practical upshot of all this is that by removing the free oxygen from your storage containers, you can greatly extend the storage life of the foods in the containers.
WHERE CAN I FIND OXYGEN ABSORBERS?
Because they are a relatively new tool on the food preservation and storage market, oxygen absorbers have not yet achieved a extensive distribution amongst the various storage food dealers and suppliers. They are available, but you may have to do a bit of searching to find them.
HOW ARE OXYGEN ABSORBERS USED?
Determining the volume of air remaining in a filled container is no easy thing. In a study conducted by BYU, #10 cans filled with either elbow macaroni or powdered milk were used and their respective air volumes were determined. A can full of elbow macaroni was found to contain 22% remaining air volume and a can full of powdered milk was found to contain 10.5%. With these as guides, you should then be able to roughly figure the remaining air volume of the foods you have in your containers. You’ll have to decide whether the food you are working is closer to the macaroni or the dry milk in its packing density. Obviously, this is a rather rough rule of thumb. The excess capacity will thus serve to cover the shortcomings of your reckonings. These absorption packets should be used only in dry foodstuffs and not with any product that will get them wet.
NOTE: If you do choose to use oxygen absorbers in packing your food storage containers you should give some consideration to the container you’re using. The absorber is going be removing the 20% of the atmosphere that oxygen constitutes. Since nothing is replacing it this will leave the interior of the storage container with a lower atmospheric pressure than the outside. If the container is sturdy enough, this won’t be an issue. For containers with thinner walls or more flexible material the pressure drop could cause them partially collapse or buckle, particularly if other containers are stacked upon them. This could make them more likely to lose seal integrity. The sturdier plastic buckets or metal cans should have no problems.
If anyone out there knows of more precise instructions for the use of these O2 absorbers, particularly if they’re from the manufacturer, I’d appreciate it if you’ll send them to me.
WHAT IS A DESICCANT?
A desiccant is a substance with very hygroscopic (adsorbs moisture from the air) properties. There’s any number of different substances that meet this description, but only some of them will serve our purposes.
The most commonly used desiccant is silica gel. This is an amorphous, highly adsorbent form of silica. It is most easily found in a form called “indicating silica gel” which are small white crystals looking much like granulated sugar with small colored specks scattered throughout.
Those specks are how we determine whether the gel is dry or has adsorbed all the moisture it will hold. If the specks are blue, the gel is dry and capable of carrying out its moisture adsorbing mission. If the specks have turned pink, then the gel has adsorbed all it will and is now saturated. Part of what makes silica gel so useful is that it can be refreshed by driving out the adsorbed moisture so it can be used again. This is a simple as pouring the saturated desiccant into shallow pans and placing in a 250 F oven for no more than five hours until the colored crystals have once again turned blue. You can also do the same thing in a microwave. Stir thoroughly and repeat until dry.
WHERE DO I FIND DESICCANTS?
I buy all my silica gel at Hobby Lobby in their dry flower section where it is sold in one and five pound cans for flower drying. I’ve seen it sold the same way in crafts stores and other department type stores such as Walmart that carry flower-arranging supplies. You can also buy it from many other businesses already prepackaged in one form or another to be used as an absorbent. All the desiccant that I’ve found packaged this way has been rather expensive (to me) so shop carefully.
HOW DO I USE DESICCANTS?
The key to storing many foodstuff for the long term is dry, dry, dry. Available oxygen and storage temperature also play roles, but it is moisture content that determines whether you get usable food out in five years or not.
Therefore, the idea here is to have the food you want to put into storage as dry as possible before it goes in and then take steps to deal with any moisture trapped, generated or leaked into your storage containers.
Ideally, the foodstuffs you have on 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 foods aren’t sufficiently low in moisture content, then you’ll need to reduce the water they contain. Wheat has been found intact in 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 which 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. 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. Stir the food frequently to maximize moisture loss. About three days of cool, constant air flow and low humidity ought to dry things out a bit. Due to its highly odor absorptive nature, I would not do this with any dried milk products or other powdered foods, flours or meals. This method works best with coarse particles such as grain, legumes and dried foods.
If you don’t want to do this, 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 desiccant 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 it saturated in storage.
I use silica gel for practically everything. My usual procedure is to save or scrounge clear plastic pill bottles such as 500ct aspirin bottles from the dollar store. 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. The paper is very permeable to moisture so the gel can do its adsorbing, but it’s tight enough not to let the crystals 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.
IMPORTANT NOTE: The indicating form of silica gel (has small blue specks in it) is not edible so you want to use care when putting together your desiccant package to ensure that is does not spill into your food.
WHAT IS DIATOMACEOUS EARTH?
Diatomaceous earth is a naturally occurring substance comprised of the fossilized remains of marine diatoms. These diatoms are microscopic in size and are covered in sharp spines that make them dangerous to exoskeletal insects, but not to animals with internal skeletons. The spines of the diatom skeletons pierce the soft body tissues of insects between their hard-exoskeletal plates and it is through these numerous microscopic wounds that the insect loses bodily moisture to the point of desiccating and dying. Creatures with internal skeletons such as humans, cattle and pets have means of resisting such damage and are not harmed. Thus, it is possible to mix a small amount of DE into your stored grains and beans to control insects without having to remove the dust again before you consume them.
WHERE DO I FIND D.E. AND WHAT TYPE SHOULD I BUY?
IMPORTANT NOTE: There are two kinds of diatomaceous earth to be found on the market and only one of them is suitable for use as an insecticide to use in your stored grains. The kind that you DO NOT WANT is the type sold by swimming pool suppliers as a filtering agent. It has been subjected to a heat treatment that dramatically increases its silicate content and makes it unsuitable for use with your foodstuffs. The type that you want is sold by several suppliers as a garden insecticide. Many organic garden suppliers will carry it. Read the label carefully to be certain no deleterious substances such as chemical pesticides have been added.
HOW DO I USE D.E. IN FOOD STORAGE?
To use, you must mix thoroughly one cup of DE to every forty pounds of grain, grain products or legumes. You need to make certain that every kernel is coated so it is better to do the mixing in small batches where you can insure more even coating.
WARNING: Since DE is essentially a kind of dust, you need to take steps to keep it out of your lungs and eyes. Even whole wheat flour dust can cause lung irritation if you breath enough of it. DE does not kill the insect eggs or pupae, but it will kill adults and larvae and any eggs or pupae that hatch into adults will die after encountering it.