Step 7: Altitude and Boiling Temperature

If you're at the top of Mt.Everest water boils at 156 F(wpedia) due to the very low atmospheric pressure there.
You'll definitely need a pressure canner to get your water hot enough to sterilize your jars.
Great explanation of canning and how it works (and when it doesn't). I'll pass this on to my canning-wary friends. Many thanks!
yummy, kiwifruit jam
<p>This works for preserving whole tomatoes, doesn't it?</p>
good 'ible. Would a pressure cooker/canner make the process go by any faster? I'm trying to justify buying one.
Do you have to have a can that has the thing that will snap when you press it?
a mason jar?
Can I use a jelly jar? It doesn't snap down though.
yes, and no... when you heat stuff, it expands, if you fill your jar with cold 'stuff' and heat/boil it, the jar will explode (if it doesn't let out air) but if you fill it with boiling hot 'stuff', and heat/boil it then, you'll be fine Making sense?
My understanding is that the 'final boil' is to expand the small pocket of air in the jar with heat causing it to push out some. Once cooled the air contracts causing a vacuum inside the jar sucking the lid down tightly, creating a nice tight seal.
some jars may not let air out
Canning USA.com has a lot of good information on canning--plus the reasons for sterilizing the whole thing in boiling water.
This is my favorite step of the process. this is a great way to preserve food and use wasted steam. Thank you ;)
boil the filled jars? Can you explain why? I've been making jam for ages, and pickes and so on, but I never did this step. Am I doing it all wrong?
Just as one more precautionary step. Better to give the whole thing one more chance to boil any potential little buggers straggling on their way to botulism heaven.
It's nice to see others keeping the old skills alive.
I thought boiling the lids (with the seals) wasn't recommended - it can melt the ring and cause it to not seal completely when further processed. Don't the instructions say to either dip the lids in water that was just boiling or just pour boiling water over them?
Definitely follow the directions that came with your lids.
very useful!
Like the POTUS said: Yes we can!
Great work here. Very useful.:)
very informative. love the charts!
It appears that you have canned kiwifruit in one photo. Would you use the same times for Kiwifruit that you use for blackberries?
Why? Because we can.
We can food almost every year since 2004, Pickles, lots of types of jam(kiwi is too expensive, is it pretty good?) pickles, tomatoes, tomato sauce, vegetables, all kinds, that canning funnel and lid magnet for picking them out of the water are really nice to use.
Very nice, my wife and I used to can, been too long.

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Bio: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output ... More »
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