Been wanting an All American for ages, and keeping an eye on local ads finally paid off! Thinking of getting back some precious freezer space and starting off by canning some stock.
[Image description: a brand-new looking All American canner 910 sitting on a kitchen counter]
Nice find! Always wanted one but its a no go with a glasstop stove so Im out of luck.
I know absolutely nothing about canning. Why does it require a pressure vessel?
Spores of Clostridium botulinum can survive boiling temperatures and can thus start to multiply if the food in question if the pH is above 4.8 and has non-lactose carbohydrates and is in oxygen free envioriment.
In practice this means that low acid foods such as beans or meats could get infected and thus be contaminated with a deadly neurotoxin producing bacteria. It is the same bacteria why infants shouldn't eat honey.
Pressure vessel allows you to increase the temperature to above 100°C thus killing the spores and allowing you to can those low acid foods safely
There's two methods of canning that are considered safe, water bath canning and pressure canning. Water bath canning only requires a pot of boiling water, but you're limited in that you can only can high acid or high sugar recipes, i.e. pickles, jams, acidified tomatoes.
Having a pressure canner opens up a lot more options, as they're able to reach temperatures of 240°F+, and so can kill the bacteria that cause botulism. That lets you can low-acid foods, like most vegetables, beans, meat, fish, stock.
If you're interested in learning more, the USDA has a great resource with information and recipes on both types of canning.
Uh, so I am going to do my own learning, but I had the idea of just baking mason jars with the lid placed on top (but not tightened). Would this not work?
Definitely wouldn't recommend it, that style of canning is no longer considered safe. Ovens tend to fluctuate in temperature, so you might not reach the required temps and times to ensure sterility, even if your jars do seal. Also, jars have a higher chance of shattering in the dry heat of an oven.
Canning and preserving food. Includes dehydrating, freeze-drying, etc.