“Dry Oven Canning” has become a hot topic in the last few months as families yearn to build up the pantry in anticipation of further economic troubles and potential shortages. There’s no question that the method is considerably easier than old-fashioned canning with a water bath or pressure canner, the question is… Is it Safe? The resounding answer is . . . hotly debated!
What is Dry Oven Canning?
Dry canning is when jars of prepared foods are placed in a heated oven (usually 200°F or about 93°C) on racks and heated for a minimum of 30 minutes. Once the jars “pop”, like in traditional canning, they are considered to be “sealed”.
The theory is that 200°F temperature is enough to create a sterile environment and that once “processed” these jars can then be stored for years, (many report up to 30 years!) safe from contaminants.
The Concerns
There are a number of concerns with oven canning…
Oven Thermometers
Oven thermometers are often inaccurate and it can be very difficult to ascertain when the contents of the jar have actually reached 200F. There isn’t any way to regulate the circulation of heat in the oven. The only way to accurately test the internal temperature of the jar contents would be to remove the lid itself, thereby compromising the food.
If you think your oven circulates air evenly think back to the last item you baked in it, was it perfectly browned all over? Did one part of the item brown faster or a bit darker?
Oven Temperature
The oven cannot be a pressure chamber, which means that the food inside the jars will never get hotter than the boiling point of water (212F) regardless of how high the air temperature is inside the oven, Basic Law of Physics Folks!
Explosion Risk
Canning jars were not designed to be in a dry heat environment for a prolonged period of time and have been known to crack, shatter and in some instances even Explode during processing.
Manufacturer’s Recommendations
Manufacturers of canning jars do not recommend baking or oven canning in the jars.
Lack of Proof
There isn’t a Single, research-based documentation/study to support that ‘canning’ any food in a dry oven as described on this web page or any page that proposes oven canning provides sufficient heating to destroy bacteria of concern.
Food Poisoning
Clostridium Botulinum- aka Botulism THRIVES in an anaerobic environment (like a jar of food!) and is Completely undetectable in an opened jar. It has No Color, No Smell, and causes NO change in taste to alert you to its deadly presence. In Short, Oven Canning is a potentially hazardous practice that can lead to food poisoning, botulism, and death. There are a number of considerably safer methods of food storage and preservation.
How To Oven Can
If you’re not convinced that it’s a dangerous practice because you read on the internet that folks have done it and you believe it’s safe enough for them, then it’s safe enough for you… then here’s a How-To (btw, we’re not responsible for any illness, this is provided for information only).
The ONLY Foods that MAY be “Dry Canned” must contain less than 10% Moisture overall. Those that use this method generally use larger jars such as quart jars, rather than pint jars.
Which food items can be Dry Canned?
- white rice
- wheat
- whole grains
- oatmeal
- dry beans
- powdered milk
- white flour
- pasta without egg (really debatable as pasta contains Oil which can go rancid easily)
- freeze-dried foods
- dehydrated foods that are crisp enough to snap such as peas, celery, carrots, onions, yams, sweet potatoes
- TVP
- cheese powder
- gelatin
- low-fat ready-to-eat cereals
- sugar
Foods that Should NOT be dry canned:
- Cornmeal
- Pearl Barley
- Nuts – due to the natural oil content
- Seeds
Dry Canning Method
(here’s how it’s recommended on the internet) Clearly, you know we DON’T Recommend it at all!
- Wash and dry Jars, be sure the rims are free of cracks and nicks
- Heat oven to 200F
- Fill jars using a canning funnel leaving 1/2″ of headspace and place them on a large cookie sheet
- Once all the jars are filled, put them in the oven and “Process” for at least 60 minutes
- Remove the jars from the oven, Wipe the rim of the jar, place a lid on and screw the band down tight
- When the lids “Ping” they are said to be sealed.
- Cool in a draft-free spot
Label and date the jars and store in a cool dark place
What this method does for Dry Goods:
- Kills eggs, larvae of bugs, preventing them from hatching
- Reduces moisture in already low moisture foods to help prevent staleness
What this method does Not Do
- Kill Bacteria Spores
- Kill Mold Spores
Troubleshooting
Jar Frogging
Foods that contain more than 10% moisture will “frog-up” and cause mold to grow. This can be due to the moisture content within the food which can be even higher due to the humidity levels in your home. So just because it’s normally a dry-oven canning item doesn’t necessarily mean that the moisture level isn’t too high due to excessive humidity.
Sources:
- National Center for Home Food Preservation ~Link~ Advises NOT to can with this method
- USDA Complete Guide to Home Canning ~Link~ Advises NOT to can with this method
- Penn State College of Agricultural Sciences ~Link~ Advises NOT to can with this method
The SAFE METHOD OF “Canning” Dry Goods:
Use a Foodsaver with a jar sealing attachment AND oxygen absorbers together to “Seal” jars containing dry ingredients with less than 10% Moisture.
A foodsaver alone will vacuum seal the contents of a jar, but by adding an oxygen absorber a substantial amount of remaining oxygen will be removed thereby reducing the risk of mold.
This method is not an actual CANNING Method. What the method is, is dry sealing already low-moisture dry goods for long-term storage. It should not be considered a “canning method”.
thank you for the the article. i’ve done research on it and i’ve found pros and cons. if i do decide to try it i will do a test batch and see how that goes.
i just don’ t see how this can be safe.
Fully Agreed, IMHO it just isn’t safe and isn’t worth trying!
Exactly. It’s not. And I think it’s misleading for the article to say it’s “hotly debated”. It’s not hotly debated among food safety agencies like the USDA. It’s been deprecated since 1940 as unsafe.
i had not heard of this process before. i very much appreciate this article, the details and information presented. i have to agree that this method seems to me to be inadequate.
why waste the time and supplies…and while you might get one or two good ones….how good are they really?
you’ll find out, when you need it most and it isn’t any good. thank you for this information!:stars::stars:
this method has been proven to be unsafe. why take a chance on eating food that could harm your body or potentially kill you.
pressure canning or water bath method are both safe and proven. you just must be sure to follow the proper instructions either from a home extension service or from a good canning book.
some of the recipes on the internet are not safe.
i’ve been home canning for over thirty years and love to eat our home grown food because it has no salt or preservatives and is grown organically.:preggers:
sorry, but i think you’re missing the point here. first of all, you state that one cannot be sure of the temperature in the oven and would have to remove the lid to test the internal temperature, but the lids are not put on until after the jars are removed from the oven.
this also addresses your other concern that jars could explode. i can see how they could if the lids were indeed on while they were in the oven, but since that’s not the case, i really don’t think the danger is very great that the glasses could explode. i think the major issue is with the term “canning.”
oven “canning” is not really a method of canning, but simply a way of trying to extend the storage/shelf life of foods that already have a long shelf life because they are dry.
rather than storing a bag of flour in the paper bag that it comes in, for example, you are putting it in a less decomposable and less penetrable storage container and try to keep it as sterile as possible. i really don’t see how you are going to pressure can dry flour!
oven “canning” is not a way of preserving foods that would otherwise spoil fairly quickly. it’s a way to safeguard the storability of foods that already have a long storage life and presumably are already free of contaminants like mold and spores. i can the regular way, i dehydrate and i oven can–each has its benefits for certain types of food, and i would disagree with your oven canning list that includes dehydrated foods.
i would never oven can home-dehydrated foods precisely because i cannot accurately assure that the moisture has been sufficiently and consistently removed.
therefore, not a good thing to oven “can”.
While that’s true, by the time you pulled it out of the oven and attempted to test the internal temperature of the goods you’re attempting to “oven can” the temperature would be reduced too quickly to cap it and seal out bacteria, thereby being USELESS, as I mentioned in the article.
Actually there have been several reported instances of attempted “dry canning” explosions of goods. Some people feel dry canning is safe and use it for Everything, including sauces, tomato products, etc we do not, nor do recommend it, as the article clearly states.
Precisely the point of the article, I’m glad you’re on our side on this issue. We’ve had far too many requests for Oven canning directions over the years and hate having to explain just how dangerous this is to ones family and ones health.
With your knowledge of dry canning you should have your own blog instead of intruding on other bloggers. Know it alls are a nuisance to society. I’ll follow this blog. She knows what she is writing about.
I use Hamilton beach roaster counter top ovens to dry can.
1 I leave the lids off the jars of dry food. This allows moisture to escape.
2 I put a wire rack under the jars for jar safety.
3 I start with cold jars and cold roaster.
4 I do 200 temp. I only put 8 jars in(quarts) at a time for 2 hours.
5 I set all lids and rings loaded and bottom up on top of roaster lid.
6 At end of time, I quickly put the hot lids on the jars and screw tight.
I over 45 years I have canned large crops of shelled pecans this way and they kept for several years. No spoiled ones. I can 1/2 gallon jars in the roaster by using a second drop in lining pan as a lid. I also use the electric roaster as a hot water bath pan to can high acid fruit. It will hold 12 quart jars!
I never use a rack in hot water bath because the heat is on the sides. I only put 8 quarts in for dry canning so the jars won’t touch the side walls.
I have not lost a jar, thousands of jars later! I do flour, rice, beans, instant milk, dry fruit, saltine, crackers, pasta, etc.
Thank you for sharing Heidiimnot.
Agree completely.I am Australian and canning jars and lids are expensive.
I have been searching for an affordable way to store dry spices and beans, possibly reusing pasta sauce jars because simply dry food storage in a jar has failed.I think the reason the lids haven’t sealed properly with just an O2 absorber is due to lack of heat.Eigther for both jar and lid, just jar, or just lid. (To soften seal).Hence my search.
Jars provide a barrier (better than mylar and food saver plastic imo), which prevents odour and scent crossing.I then store in dark bucket/container.I am a little reluctant to heat my product though.Regardless, I do believe dry oven storage certainly has a place in food storage.
interesting, i wouldn’t try it but it is interesting. i don’t can anymore. i used to help my grandma all the time.
she had a big garden back then.
we don’t have one anymore.
you need to have 3 things happen for Botulism to thrive and grow are: Lack of competing bacteria, low acidity, and low oxygen levels. You have created all three with oven canning and I would say by doing this type of canning you are risking growing the Botulism toxins on your food and risking your family’s heath. Not worth the risk.
If you want to make grains store for extended periods of time, then store them in food grade buckets and put dry ice on top until evaporated or use oxygen absorbers.
Much easier and more safe.
Are you talking about dry canning in the oven causing botulism ,,,,or wet canning in oven ,,such as sauces , meats ect! How could you get botulism from dry canning flour or rice ?
what are oxygen absorbers?
wow i would be very careful trying this method. there’s a good reason the old fashion way is the best…cause it’s safe ! that’s the only way i do my canning.
i always store my flour and rice in large glass jars with tight fitting lids or tins like the popcorn tins from christmas, after putting the bags from the store in freezer for 3 days to a week or longer (if I don’t get back to it immediately)
to kill any insects or eggs that may hatch or be in there, I then empty into jars or tins and close with lids…..I don’t see the necessity of putting it in the oven to seal,( oven canning) it stays shelf stable for a good while and if I want longer storage I use the oxygen absorbers and vacuum seal.
as for the temperature of the food in the jar, we can put an electric oven thermometer probe into the food. the thermometer will buzz when the temperature reaches the programmed 200°.
we always stored our bulk dry goods in old 5 and 10 gallon food service pails. We would add a chunk of dry ice, and tamp down the lid with a rubber mallet. This is for long term storage though — I mean it lasted for years with no bugs, no issues.
For shorter term, simply putting the stuff in an empty jar with a tight fitting lid should suffice, especially if kept cool.
I put my dry goods outside for a couple of days when its below zero, to kill bug eggs present in all grain. (Same thing I do for blankets and pillows to kill dust mites).
regarding oven canning… i have sterilized the canning jars the traditional way, then left them in a 200 degree oven. I kept the lids under boiling water, carefully filled the jars half way with cake mix or bread mix, and cooked at the temperature for the mix, until done.
I left the cooked jar cakes in the oven till it cooled just enough not to melt away the rubber seal (using my own judgement), and topped with the sterile canning lids.
They sealed, and then I put the breads and cakes down in my basement pantry. They kept fine – all of them. No mold or bacteria growth.
They were very moist too.
I used the wide mouth pint jars, so they slid out nice for slicing, like the old fashioned brown breads that we used to slide out of the can.
However, these were commercial mixes with preservatives, and the cakes high in sugar as well. I wouldn’t trust oven canning for any wet food that would require the pressure to kill botulism spores. You can’t take short cuts with canning.
But I don’t see any reason that dry good like rice, beans, can’t be oven canned though for added longevity.
I mean, I just toss mine in any old jar and store them in a cool, dry place.
I just trie oven canning ,rice , oat meal , and pasta ,,, did to correct temp and time , and jars and lids totally clean and dry ,,and was happy to hear all the popping and sealing ,,, then noticed in the jar moisture ,,, condensation on the lid when I removed it ,,, was totally disappointed !!!! Removed all lids , poured contents on cookie sheet , put in to oven to dry and bagged up in ziplock baggies ,left open till totally cooled ,,,,with rice I oven dried and attempted oven canning again ,,, same scenario,,,, what if people are doing this and see and ignore condensation,,, or never notice it ,, even a little bit is dangerous ,,, I would never recommend this method to anyone period!,,,
Thank you for sharing your experience. That is precisely why we explain what it is and why we DONT recommend people use it as a viable method of canning.
i have not dry canned, but i do: breads (banana, amish) & cakes in jar’s, in the oven! they last in pantry for a year. they turn out, wonderful.
just saying
I think I’ll stay with the water bath method….tried and true and all
This was written several months ago but I am researching oven canning. As I have read the article and the comments I have to note that the alternative way of preserving is to use oxygen absorbers and dry ice to remove oxygen. the comment “Botulism THRIVES in an anaerobic” is absolutely true which is what you have when you remove oxygen with oxygen absorbers and dry ice.
It is my understanding that the reason for the oven canning is to kill mold and larva.
I am still learning but botulism is present any of the above methods will not work.
One of my relatives used to dry-can food items and she swore by it but most of us in the family wouldn’t eat anything she made. She always had health issues when she was still alive, now we know why.
Reading your many comments above, one would think there was a botulism epidemic killing millions of people. Dry ice is frozen carbon dioxide. It is an acidifying agent because when it reacts with water it forms H2CO3, carbonic acid.
This is a well-known chemical reaction.
Saying there is no acid in foods treated with dry ice is chemically incorrect.
Botulism is not a problem in the presence of acidic food or acidfied food. It is a problem with non-acidic foods like green beans and corn. It is generally not a problem with natural dry goods like flour and seeds.
It is a much greater problem when blood from any animal is present, as that is a natural substrate for the baceria to thrive in and grow.
Spores of Clostridium botulinum are present in the air everywhere (as are the spores of mold and other contaminants.)
They only do harm when the right conditions are met for Clostridium botulinum: liquid, anaerobic and neutral or alkaline conditions in the liquid.
The botulinum poison is easily destroyed by boiling any questionable contents for one minute or longer.
Anecdotally, the following scenario has been documented numerous times by pathologists: the most common person to die from botulism is the mother preparing food for dinner. She will lick her hand when the juice of a canned good splashes on her hand while opening a botulism-contaminated canned good.
Then she heats the canned good for her family’s dinner. They all survive, but she dies. She dies because the botulism poison is most toxic/deadly in its natural state.
They don’t die because heating it to the boiling point destroys its toxicity and it becomes harmless.
For everyone’s information, botulism is a protein produced by Clostridium botulinum. Proteins are altered by heating. Most people know that when you cook an egg, the egg “white” goes from a clear, viscous (snotty) consistency to a white, rubbery consistency.
This is heat transformation of the protein structure.
Thank you!
Good evening ladies and gents,
I have been reading your comments and set here scratching my head. You all act like this is all some kind of newfangled Gizmo or something, Humanity has been here for hundreds of thousandths of years and prepping or long term food storage is nothing new.
I was born into a family of preparers or as they said survivors of the great depression. I guess I am a bit older than most of you. I am 71 and a half years old and I have lived on stored food for 71 of those years (mom weened me off the breast at about 6 months old.)
Mom dry canned a lot of dry goods because we stored everything in the basement (dirt walls and floor). That was to keep the vermin out of our food. Mom Dad my two brothers and I ate that food every day.
Dad died early at 81 Mom died at 90 and My brothers (all alive) 85, 79, and 71 are doing just fine.
The most impotent thing no one has talked about is To Keep Rotating Out The Older Stuff and replace it with this years crop. You Don’t need 50 years of food stored. That is ridiculousness.
By the way if heat round everything I guess you all don’t eat canned processed food. and as for longevity if canned food When I was in VietNam I ate food out of a can that was canned during the Koren war 3 times a day for 11 months.
I have been oven canning for 20 years. I was told back then that the entire reason to oven can is to eliminate the hatching of any eggs deposited by the various bugs that come in the sack of flour, rice, etc. This method allows one to buy dry items on sale and ‘preserve’ them until needed. I’ve never had a jar break on me.
The person who taught me said the oven needs to be 225-250. The empty jars are placed in the oven for 30 minutes to help sanitize and dry out the inside of any moisture. Each jar is removed from the oven, filled, then returned to the oven then get the next jar. It is time consuming but it has saved me many a time from throwing flour, rice, beans, etc because of bugs. I live in the country where there are other creatures besides bugs to get into dry foodstuffs.
I’ve dry canned for years without any issues, but I do agree that the items must be extremely low moisture and for gods sake, don’t can when it’s raining out or high humidity or you’re just asking for a case of botulism.
I wanted to learn about dry oven canning because it sounded like a safe and easy way to preserve food. I was scared of water bath canning because of the risk of botulism, so I thought dry oven canning would be a safer option. I was wrong. Dry oven canning is actually much more difficult and time-consuming than water bath canning, and it doesn’t work nearly as well. The food doesn’t taste as good, and it doesn’t last as long. I wouldn’t recommend it to anyone.