Usually BWB is a bit longer processing time due to the heat getting only to 212 degrees (boiling point). If pressure canned, the stema can reach temps above 212 degrees and will het faster due to that condition. Acidic foods don't need pressure canning. That includes most jellies, jams, pickles and tomatoes (with added acid). Food density also comes into play. Pressure canning is usually meant for most low acid foods. A pressure canner can be big enough to hold jars with 2 inches of water over their tops, with a lid that isn't clamped on, then its considered a BWB canner too.

Is there a reason why you want to pressure can instead of BWB?

I spent a lot of money on a big All American pressure canner so now I want to use it as much as possible and it seems a quicker way to can than with a BWB and you use less water.

Realistically, there's no reason why you couldn't use your All-American and pressure can for the same time at 5 psi. With some delicate products there may be a change in quality, but that applies to few items. For example, with some sweet preserves (i.e. jelly) the additional heat may break the jell.

You may find, though, that it isn't necessarily a savings in time because you have to bring it up to temp sufficient to vent steam for 10 minutes then process at pressure for x number of minutes then cool down until the pressure is back to zero then add the wait time of 10 minutes before removing the jars.

It is, however, a savings of water and weight. Also, depending upon the All-American, you can stack jars and do a larger load in one session.

Carol

Agree. The two canning process are not interchangeable. Pressure canning is not as time-saving as it might seem to be. Saves water but that is all and the changes it causes in food quality is the best reason to use it only when required by the recipe.

If your goal is just to get the most use out of your pressure canner then just use it as a BWB canner when that is what the recipe calls for. You'll be much happier with the end results if you stick with the recipe instructions.

Dave

Thank you all !

I'm with you - I pressure everything, even jams and jellies because it's so much more convenient - and safe - for my situation. I've gotten several conversions from the extension office and they seem to run in a pattern. It's usually one-third of the time. Yes, you have to allow for the venting (in a BWB, you have to bring the water to a boil) and I certainly don't want to scrimp too much. Sometimes it's ten lbs, sometimes a little less, like james are 5 lbs for 5 minutes, reslishes seem to be 8 lbs. Call your ext office to be sure.

If it's a boiling water bath recipe, I see no reason why anything more than 5 psi is necessary. At 5 you're still at a higher temperature than BWB and you're not cutting the time, so why go up beyond that?

Maybe I'm missing something in the science?

Carol

Thanks Gran but re the ext office - I live in South Africa where no one even knows what pressure canning is - the joys of living on the other side of the world :-)

south africa!!!! how fantastic!1 Maybe you can carry a little knowledge and spread it around. Good luck.