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]
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