I'm thinking about buying a pressure cooker and so far I love these giant All Americans. However, they are aluminum. I'm not sure this matters for some processes, like sterilization jars for mushroom growing. I am even reading about people processing cactus in aluminum Pressure Cookers without problem.

I see that one could not put a strong acid or base in the aluminum..... but would it be possible to put a smaller stainless pot inside the giant pressure cooker to achieve the same effect?

I'm really excited by the idea of getting one, and can even do some at-home canning! Just want to make sure I spend my money wisely and get something that I can use in many different ways.

Thanks everybody for reading.
Moon Moon

A pressure cooker is absolutely necessary for sterilization, unless you have an autoclave. Heat alone, especially from boiling water, is not enough to kill many microbes, which is why pressure is necessary. If you only boil or use steam to sterilize, you haven't actually sterilized anything at all. Just google endospores for one example of why heat alone is not commensurate.

Also from what I understand, you can put other vessels into the pressure cooker to hold liquids or materials, within the realm of common sense (ie. sealed, carbonated fluids would probably be a no-no).

actually, https://en.m.wikipedia.org/wiki/Tyndallization

The All-American is pretty awesome, I'd get the same. A pressure cooker should be as big as you can go. Don't worry about the aluminum, if you need to pressure cook something acidic, you can just put it inside a large mason jar, and pressure cook it like that.

You're not telling what you want to use a pressure cooker for.

Aluminum is actually more sensitive to base than to acid. Very dilute acetic acid shouldn't hurt it too much, unless you add sodium chloride, which will form hydrochloric acid in combination with acetic. You can mitigate these issues by enclosing your substrate in closed glass canning jars.

In Europe, aluminium pressure cookers are not sold anymore. All pressure cookers in the stores are made from stainless steel.

Regarding Tyndallization, I have personally not have achieved reliable sterilization by it. Using a pressure cooker works much better for me. If the goal is enhanced cell lysis, Tyndallization is no more useful than simply boiling.

I've had good success with tyndallization of liquid cultures, typically done in threes.
the first boil kills non-endospore bacteria, while activating the endospores. the subsequent boils eradicate the endospore bacteria.


PC'ing in the OP's context is purely for cell-lysis, in acidic phase.

I have yet to buy a pressure cooker, so this topic is interesting to me. I wanted to chime in and say that I have had great success with Tyndallization, and three times really is key for killing off a few generations.

I have a sneaking suspicion that the altitude matters. I live in an area where the air is thinner, so perhaps that makes it a little easier for me to get away with an inferior method.

What are the most common failure mechanisms in pressure cookers? Are there significant advantages to stainless steel? What parts need to be replaced most often over time? I'd like to buy something that holds together well and is easy to fix more than anything else

the silicone rubber gasket warps over time.
stainless is inert, and thus won't oxidize as easily in the presence of basic solutions. aluminum will blacken and flake.


I proposed this method in 2010, when someone handed me a few gallons of hydrated sp powder that had the consistency of goop...it was simply rehydrated cells that needed to be lysed. normally, I would've pinged san pedro cells with an ultrasonic probe, but the volume was too much...so I put the goop in several quart jars, with vinegar, and pressure cooked for 50 mins. the result was a more manageable syrup, which I basified and processed into very pure mesc sulfate. the PC I used was a 6-qt Presto, stainless steel.

This is the kind of thing I'm thinking of (link to amazon):

My main reason for wanting it for sterilization for mycology. I'm about to embark on an adventure into the world of fungus, and this seems like a necessity.

But I'd also would like to be able to break down barks or cactus in it. I guess for bark or cactus I wouldn't really need much if any acid (vinegar). It just seems like I read a lot of warnings about using aluminum. Nice to know I just put other containers in there.

And just to mention, this brand of pressure cooker does not have a gasket at the lid. It's a metal to metal interface. I don't know if that's better or not, but there it is.

I've never heard of Tyndallization; but now I can read more about it, thanks!

I'm happy to hear positive feedback about the All American. It looks like it should be part of a nuclear submarine. Thanks everybody!

Moon Moon

Essential for mushroom cultivation, and very useful for small scale extractions (cuts boiling time in half). But I prefer large scale extraction in a giant pot rather than few smaller ones.