Exploding canning jars

[Arkgrandma]

My daughter roasted chili peppers, then peeled them and made green enchilada sauce to can. She added onion, garlic, cilantro, a couple other seasonings, and added a little flour for just a little thickening. She canned them over the weekend and had them out on the counter on a doubled towel and when she got home from work yesterday, several of them had exploded. We would love to hear your suggestions as to why this happened. Thank you!

[jvcstone]

water bath or pressure canning???

JVC

[Jjr]

Were the jars true canning jars, or repurposed jars? Repurposed jars being like mayonnaise jars before they went to plastic, and other similar commercial products in glass jars, which are not as thick or strong as true canning jars.

More information is necessary, like the process, process procedures, and type or jars being used before any assessment of the possibilities can truly be analyzed. Other thoughts which come to mind is were the jars allowed proper head space or over filled?

[Arkgrandma]

water bath

[Jjr]

Some more things, I though of:
1. Were the jars inspected prior to use for fractures or cracks?
2. Were the cooling jars arranged to leave an air space between the jars?
3. Were the jars protected from any direct cool air currents?
4. Were all air bubbles removed, or attempted to be removed from the product in the jars, before they were initially sealed?
5. Already partially mentioned, but were the jars, New, Used or repurposed?
6. Was the towel completely dry before the processed jars were placed on it to cool?
7. Is you daughter certain she did not scratch the jars in any way during her processing procedure?
8. Is the canning location in excess of 1,000 feet sea level? Were properly adjusted canning times use? Admittedly this last one is grasping at straws, and it usually result in improperly processed foods which spoil, rather than causing breakage, but thought I would mention it also.

[Arkgrandma]

She used real canning jars and follows instructions very well. She has canned salsa, apple butter, potatoes, etc. This is the first time she's had a problem......oh, she just messaged me on fb; said it was the flour. She googled it and it said the flour absorbs the acids and can cause the problem. I never heard of this before but if it's true, she sure won't put flour in the jars again....I told her to add the flour to the sauce when she's heating it on the stove, not when canning. Thanks to jvcstone and Jjr for your input.

[Jjr]

Hopefully it was not an expensive lesson, but I am sure it is one she will remember forever. Little things can & do often make big differences in outcomes.

[wildturnip]

All the canning books say not to add flour or any starch to recipes that you are going to can.

[Arkgrandma]

Thanks, wildturnip
I guess I've never wanted to can anything that required thickening and neither has my daughter. This has been a great lesson learned with no harm to anyone. The jars exploded while everyone was at work, otherwise, someone could have been close enough to be hurt. Again, thank you.

[CountryMom22]

Wow! I learned something today, for sure! Glad no one was hurt.

[wildturnip]

Yes, that's scary! Glad no one was hurt.

[anna]

Its a blessing that the jars exploded because I don't think that is a safe recipe for water bath canning.

I sincerely hope she didn't water bath potatoes. They absolutely require pressure canning.