Learn how to use oxygen absorbers to dry-pack food. Dry canning with oxygen absorbers lets you store food on a shelf rather than in your limited freezer space.
The internet is a wonderful asset to gain knowledge on just about anything. But it can also lead you astray, as I found out the other day. My recent preservation experience started with a YouTube video on “dry canning,” also known as “oven canning.” Although I can many of my own fruits and vegetables, I never thought too much about canning dry foods. I’ve always put my flour, cornmeal, and some other dry goods in the freezer, because of the bugs that can get into those items if not stored correctly. Unfortunately, this takes up a lot of freezer space, so I was thrilled when I came across a video on oven canning. I thought I’d found a new way to store bulk dry goods without worrying about spoilage. However, with a little more research, I found out that oven canning isn’t a safe method of preservation, and isn’t even canning at all! (See “Unsafe Oven Canning” below for more details.) Fortunately, I also discovered how to use oxygen absorbers as an alternative way to safely store dry foods for a lengthy amount of time — and you can still use your canning jars.
Dry canning with oxygen absorbers
Oxygen exposure causes food to spoil, so removing oxygen from your dry goods will let them retain their freshness and quality for long periods of time. You can achieve this by “dry-packing,” or storing foods in oxygen-free containers with sealed lids, such as canning jars. This will prevent mold and bacteria from growing and will kill any lingering pests. Properly packed foods can be stored for years as long as the seal remains intact. This can allow you to buy in bulk and put away large quantities of dry foods, as long as you have the shelf space. Although this technique frees up a lot freezer space, it will take up space in other parts of your home. For example, it takes 24 quart-sized jars to store 50 pounds of rice. Because temperature and light will also affect the quality of your stored items, you’ll need to have space to keep jars in a dark place where the temperature is consistently below 75 degrees Fahrenheit. Dry basements and storage cellars work well. If you don’t have either, keep your jars in a cabinet or closet that won’t require you to open the door regularly and expose the jars to sunlight.
Always check your jars before consuming the food. Discard the contents if there’s condensation in the jar, if the jar is cracked or damaged in any way, or if the food is discolored or emits an odd odor.
In a nutshell, dry-packing is best for foods that have less than 10% moisture with a low oil content. Foods that contain long periods of time. Pasta, cereal, white rice and white flour (not brown rice or brown flour, which contain oils), dry beans, corn, powdered milk and eggs, herbs and spices, and other similar foods are excellent choices for this type of preservation.
Freeze-dried foods also store well this way; just make sure the food is completely dry without any ice crystals. You may be tempted to preserve sugar and salt as well, but there’s no need, because these items won’t go bad when exposed to oxygen. Simply store them in airtight containers and they’ll stay good indefinitely.
Here are two simple methods for safely packaging dry goods in canning jars.
How to use oxygen absorbers
Oxygen absorbers are little packages containing iron powder. In an airtight environment, oxygen molecules will “stick” to the iron. These little packets can reduce the amount of oxygen in a container to less than 0.01%. When used on its own, this is the safest and easiest packaging method.
To use oxygen absorbers, simply put dry food in a clean canning jar or Mylar bag, place oxygen absorbers on top of the food, and seal the jar with a lid and ring. It takes approximately 30 minutes for the packets to absorb the moisture in the jar and for the jar lid to seal. Oxygen absorbers can also be used with food-grade 5-gallon buckets to store large quantities of food. When doing this, keep in mind that each time you open the bucket, you’ll be exposing the contents to oxygen, so the food won’t stay fresh for as long.
You’ll need to work quickly when using oxygen absorbers to ensure they’re not exposed to the air for any length of time before you put them in jars; otherwise, they’ll be rendered ineffective — wasting your food and your time. It’s best to have all of your jars cleaned, filled, and ready to go before opening a package of absorbers, because they’ll all be exposed at that point, and you’ll need to quickly transfer them to your jars. As you’re handling the absorbers, feel the packets to make sure the powder is loose inside. If it’s hard, that means the absorber is expired.
Before you begin, you’ll also need to calculate how many absorbers you’ll need per jar. If you don’t use the right amount, you can risk oxygen exposure. A good rule of thumb is to use enough absorption to deoxygenate the entire empty jar. Usually, 100 cubic centimeters (cc) of absorption is recommended for pint containers, and 200 cc for quarts.
Vacuum sealing
For shorter-term storage, you can vacuum-seal your jars to remove most of the oxygen. This method isn’t as effective as absorbers, so it’s best to use vacuum sealing for food items you know you’ll be using within a year or so. It can also work well to help add a bit of preservation time to foods that have a moisture content higher than 10%. If you don’t already have a vacuum-sealer capable of working with canning jars, this method can be more expensive upfront. However, it saves you from having to repeatedly purchase oxygen absorbers, so if you’re primarily interested in shorter-term storage, it might be the more frugal choice in the long run. When using a vacuum-sealer, make sure each jar lid seals correctly.
I don’t have a vacuum sealer, so I’ll be using oxygen absorbers. And I’ll definitely be rearranging my fruit cellar to make room for dry goods. I like the idea of always having supplies on hand when needed, and buying in bulk will allow me to save some money. Plus, this is just one step closer to becoming self-sufficient, and who wouldn’t like that?
Unsafe oven canning
Oven canning, or dry canning, is a technique that’s been around for a while, but it’s surged in popularity over the past few years. You may find some seasoned home canners who swear by it, but the National Center for Home Food Preservation doesn’t consider oven canning to be a safe method of food preservation. During oven canning, dry foods are placed in jars without liquid, and then the jars are heated for a while at a low temperature in an oven — the idea being that it produces similar results to water bath or pressure canning. However, this technique doesn’t effectively seal out moisture and may not heat the contents to a safe temperature, so botulism can contaminate the food. Additionally, canning jars can break or explode inside an oven, because they aren’t made to withstand high temperatures without liquid inside.
When undertaking any food-preservation project — especially if it’s something you’ve never done before — thoroughly research reputable sources to confirm you’re following safe practices. For more information, visit the National Center for Home Food Preservation at www.NCHFP.UGA.edu.
Lois Hoffman is a freelance writer and photographer with more than 20 years of experience covering topics related to rural living. She lives on a 37-acre hobby farm in Michigan.
