Oven canning tomatoes...thoughts?

[jen8753]

I came across a recipe for canning tomatoes that uses an oven. You put the jars (with lids on) on a cookie sheet in the oven at 250 degrees for 75 minutes. Thoughts?

[northerngardener]

Air does not conduct heat as well as water does. The temperature at the center of the jar won't get hot enough for long enough. I definitely would not oven can tomatoes. Hot water bath or pressure can.

[hobbitlady]

I'm doubtful too. I've read that modern tomatoes simply do Not have the acid content of tomatoes 100 years ago. The acid has been bred out of them! I guess heirlooms are OK though??? The potential botulism in the middle of the jar Must be addressed. 250 degrees is probably a hot enough temp.for that amount of time,but what I've read is 240 degrees PLUS pressure canning....pressure makes a big difference (or waterbath boil but for longer than pressure canning).The acid issue is key though.
It's also easier to make a mistake and get broken jars when dry canning. People do it;so it must work for them,but it seems a bit risky to me,unless enough extra lemon juice or citric acid is added to the tomatoes to make bacterial growth impossible. For me lemon adds an off-too-tart taste (and citric acid was Yuck when I used a little once...just too strong) but can be "fixed" with a teaspoon of honey after the jar is opened and used to make the tomatoes taste almost normal. I've done that for my last seasons batch of not ripe or sweet enough tomatoes.

[Raeven]

Me three. Oven canning is not a good idea for the very reason stated by northerngardener. Heat in an oven is uneven and can't be relied upon to heat all jars and/or contents evenly. And as hobbitlady points out, botulism is a concern if you don't acidify your tomatoes sufficiently.  You'll get a seal, but you can't guarantee you've sterilized the contents of the jar.

Personally, the lemon juice doesn't bother me, so I always add it and then waterbath can my tomatoes. Oven canning is fine if you just want to create a quick 'n dirty vacuum seal for dry goods... otherwise, I wouldn't rely on it.

[jen8753]

Thanks so much