Pressure canning wort – the science behind processing times?

[d_m_s_00]

I’m trying to figure out where the processing time and psi for canning wort comes from? The guidance on the internet is 15 or 20 min at 15 psi. Who came up with these numbers or what calculations did they use to figure it out? There must be some way how to determine if the guidance is safe or not other than the infamous “some guy on the internet did it and he was ok”

 

[brewtime]

I can mine for 15 minutes at 15 psi and have not had an issue. I got the time and PSI form the instruction book that came with the canner. RDWHAHB

 

[ong]

Well, the only reason the psi really matters is that it affects the temperature the wort can reach. At 15 psi at sea level, you can reach 250 degrees Fahrenheit.

 

[JoeyChopps]

I also do mine at 15 psi for 15mins and have had great results and it makes making yeast starters so much faster.

 

[Agent]

Food canning times aren't necessarily scientifically predictable, but rather come from testing specific recipe combinations and conditions until it yields the desired result every time.
I would be inclined to say that the derivation for wort canning times comes from soup stocks with a little plus on the pressure side for safety's sake. Most official canning information sources have their times for plain stock in the 20-25 minute range at 10 PSI.

 

[d_m_s_00]

Food canning times aren't necessarily scientifically predictable, but rather come from testing specific recipe combinations and conditions until it yields the desired result every time.
I would be inclined to say that the derivation for wort canning times comes from soup stocks with a little plus on the pressure side for safety's sake. Most official canning information sources have their times for plain stock in the 20-25 minute range at 10 PSI.

Thanks, that's kind of what i was looking for. i was hoping that there was some calculation that was used, but i guess it's more of a try and test/measure thing that they must do in a lab.
I wanted to use the 1/2 gallon jars for wort, but they (USDA) only recommend them for apple juice and grape juice. i was hoping there was a calculation i could use to see how to process them to be safe.

 

[BBL_Brewer]

Thanks, that's kind of what i was looking for. i was hoping that there was some calculation that was used, but i guess it's more of a try and test/measure thing that they must do in a lab.
I wanted to use the 1/2 gallon jars for wort, but they (USDA) only recommend them for apple juice and grape juice. i was hoping there was a calculation i could use to see how to process them to be safe.

I can wort in half gallon jars for making large starters. 15 min @ 15 psi and you're good. As long as the lid is still sealed when you go to use it, it's good. I've canned more starter wort than I begin to count and never had any problems. I know there is a credible source out there that confirms the 15 for 15, but I'm too lazy to go look for it right now. I'm pretty sure 15 psi results in a temperature that will kill botulism spores.