10 October 2010

Oven Canning

We are home for a few days,
waiting for repairs to 'Ole Blue's (our elderly pickup) transmission,
and The-Man has been making good use of the lull in activity.

We have a bunch of dry grain flakes,
nuts and seeds that we have stocked up on,
and we need to clean out the freezers for moving,
we are planning to live off grid anyway,
we are experimenting with ways of preserving our food
that do not require long-term use of electricity.

I remembered my momma used to can cereal flakes and nuts
in jars in the oven, but I couldn't remember all the details.
Turns out, neither can she!
So we decided to experiment and see if we could figure it out.

First I did an internet search for "oven canning"
and the discussion I found was quite interesting.
Seems like there are folks still using this method for all kinds of foods
although the USDA recommendations are against it.
I would encourage you to read the discussion
and come to your own personal conclusions--
take responsibility for yourself and your family.

Our opinion, at this point, is that
we will continue to use hot-water-bathing
and pressure-canning
for foods preserved in liquids
according to advice in our canning books.
More or less.

Dry goods, though, are different.
We are not trying to destroy botulism organisms in liquid,
rather we are aiming to vacuum seal the dry goods
to avoid progressive rancidity or the formation of mold.
We do have a vacuum-sealing device,
but wanted something that we could be more confident would last a long time,
with as little expense incurred as possible.

I did not find any of the above mentioned discussion to
specifically address the canning of dry goods,
so, though entertaining, my research was not greatly helpful.

We tried several different approaches,
but here is what we found to give
consistent and satisfactory results:

First off, make sure your canning jars are sanitized and thoroughly dry.
Place cookie sheets on the very bottom rack of the oven
and remove any other racks.
Preheat your oven to 250 degrees F.
Fill your clean and dry jars with the dry goods and set aside.
Bring a small kettle of water to boil on the stove top
and in it place your seals, allowing them to soften in the boiling water
for 2 to 10 minutes.
Meanwhile, fill a large kettle with hot tap water,
either in your sink or on your stove top,
whichever is convenient to your work location.
When your oven is up to temp,
and working quickly (extra hands are helpful at this step)
do this for each jar of goods before placing it in the oven:
Dip each jar of goods into the kettle of hot water for a few seconds,
but don't submerge it--
only have the water come up about 3/4ths of the way to its top-- 
you don't want to get water inside your jar!--
pull it out of the water and then
wet your finger with warm water
and run it around the top of the canning jar,
then quickly place the wet hot seal on it and
screw down well with the band.
(You want to create a good seal this way.)
Next put the jar back in the kettle of hot tap water
and let it sit there while you dip and seal the next jar.
When the next jar is lidded and ready to sit in the water "bath"
pop the first one into the oven onto the cookie sheet.
Pre-heating the jars this way prevents them from cracking
due to sudden temperature change when you place them in the hot oven.
Leave some space between the jars--
you don't want them to touch each other.
When all the jars are in the oven,
close the door and set the timer for two hours.
Walk away and leave it alone.

When the two hours are done, turn the oven off.
Do NOT open the door!
Just leave it alone and let the whole thing cool
over night or around 12 hours.

After several hours you should begin to hear
a "tinking" noise coming from the oven occasionally--
as the jars cool, the vacuum creation process begins,
and the tinking sound is the safety seal being pulled down in the seal/lid.
(This is beautiful music to your ears--trust me!!)

When completely cooled, remove jars from the oven.
Test each seal to see if it is sealed.
(It should be solid when you press it,
not have any flex or go up and down.)
Any that did not seal should either be reprocessed
or used soon.

There can be many reasons for the lids not to seal,
including--but not limited to--
a nick in the top of the jar that prevents a seal forming,
not enough moisture to create a good seal,
rubber on seals not soft enough, preventing good seal,
a defective lid.....etc.
Don't be discouraged, this doesn't happen very often.
Keep trying and learning!

We prefer to eat raw nuts,
as the nutrients are more readily absorbed by the body,
and I was concerned that this method might really toast the nuts.
We found that a few nuts on the bottom of each jar get a little browned,
but amazingly the rest taste pretty much raw!
Same thing with cereal flakes and grains.

On our most recent "moving" trip to the farm,
The-Man was digging around in the basement
of daddy's house for more canning jars that my momma had stored there.
and was also clearing off some shelves to make room
for us to store our canned goods temporarily
until we can get a place built of our own,
when he came across some jars of nuts my momma had canned years ago.

Now, my momma has been in a nursing home for almost 6 years,
so we know those nuts had been oven-canned for at least that long,
and I'm guessing probably even longer.
We brought several jars home to try
and were very excited to discover that the ones in which the seals were still good
tasted as fine as could be!
There were walnuts, almonds and pecans.
A couple of jars had rusted through the lid,
(their basement is very damp, often has running water...)
losing the vacuum seal, and in one of those the nuts were rancid.
The other had just a tiny hole,
and 99% of the nuts were good, we only found a couple that were bad!
I had planned to take pictures of them--
but we ate them up and I think I already threw the rusty lids away!
Oh well, if we find more on our next trip, I'll grab a picture then.

Also, my momma did remember that she found the directions to
oven-can dry goods this way in an old farm cook book...
I will try to find that when I'm out there again,
and will reprint the directions in another post.

I am anxious to try preserving brown rice this way.
It takes up so much freezer space,
but goes rancid very quickly if not kept frozen.
I'll post an update when we do that...

So there you have it,
the very latest in "experimental research!"
We are very satisfied with our results, so far!


  1. This post was absolutely fasinating. Very educational.

  2. It has been fun to learn...can't wait to find my momma's old cookbook and see if we "did it right"!

  3. I have bookmarked this web site- very fun to read and I will try this...the music is wonderful! Thanks. Kat

  4. So glad you stopped by, Kat! I hope to be able to post again soon on a fairly regular basis---we are about to wrap up our transition, be the Good Lord willing! Blessings.