In science and medicine, the autoclave is the standard method of sterilization. It uses high pressure so that liquids can be brought above 100° C (usually 121° or 135°). It’ll kill everything*. Or at least it kills most pathogens**. Well, it still seems to kill enough for everyday purposes in the lab or hospital.
But what makes autoclaving necessary in the first place? I take it someone, many decades ago, decided that ordinary boiling wasn’t enough, since some pathogen was surviving. What is it that survives 100° at standard pressures?
*Well, mostly everything. This bacteria laughs at the autoclave, kicks back, and enjoys a nice relaxing dip in the hot tub. Though it has no interest in us, thankfully.
Botulism spores are the standard “really resistant bacterial form”. I don’t know if your lab’s autoclave people use them, but you can buy vials of botulism spores for testing if your autoclave is working properly. The idea is that you put a vial in with your run, and when it comes out, you incubate it like a regular bacterial culture. There’s a pH indicator in there that tells you if anything grows. If it does, then you know your autoclave treatment wasn’t sufficient to kill all spores.
Ah. For some reason I thought that botulism spores could be killed eventually at 100°.
For home canning… how do you sterilize then? My understanding was that thorough boiling was enough, but problems arose when the whole jar didn’t reach 100°.
The USDA and other resources recommend pressure canning, rather than hot water bath canning, for not-very-acidic foods, to avoid botulism. Linkie from the National Center for Home Food Preservation at the University of Georgia.
If you kept it at 100 degrees, it would kill botulism…eventually. There’s an equation out there that lets you swap temperature, pressure, and time back and forth. I learned it in my food micro class, but that was close to a decade ago.