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How to build a pressurized hot water extraction system at home for extracting mushroom Answered

I am currently looking to build a system that will allow me to boil medecinal mushroom under pressure. Why you ask? Because studies have shown that high temp under normal pressure will destroy the chitin( the building block of mushroom as opposed to cellulose for plants), but will also destroy most of the medecinal compound.

What is needed here is a system that can sustain pressure of around 55 psi minimum. My first guess is to get a pressure vessel that can whitstand more than the required 55 psi in order to limit the risk of failure and explosion. See an example here ;


I do not need more than 1 liter for the pressure vessel but it seams that they don't make them smaller than a gallon.

Now the big question is, how do I get the water boiling using one of those tank? I can't just put it on a stove! But if you know of something can could safely reach 55 psi and go on the stove please let me know.

Also I was wondering what keeps the pressure inside the container? Does it need a water pump to maintain pressure by pushing more water in the vessel or does it merely builds pressure with steam until it reaches his capacity?

Thanks to anyone who's willing to give me some pointer, I truly appreciate.


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2 years ago

Hey Jack thanks for taking the time to help me.

First of, if you try that with the pressure cooker please be careful, as you know high pressure water is very dangerous.

As for temperature ; I need to get high pressure and the corresponding boiling point. The reason being that water becomes a better organic solvant at temperature above 100 C. Also it as been established that Beta-Glucan, which is the most important compound in medecinal mushroom, will be better preserved under high pressure water boiling. With good equipement, it seams that the best would be to get to 160 celsius with 4 mpa of pressure. At 4 mpa the boiling point is far beyond 160, but I can't hope to get to 4 mpa. The temperature at which point my water will boil should coincide with the pressure I can generate.

Here is a couple studies that best explain the logic behind what I am trying to do.

1- This one explains why PHWE is usefull and effective (PHWE stands for pressurized hot water extraction) ; https://www.sciencedirect.com/science/article/pii/...

2- This study looks at PHWE for shaitake mushroom ; it does mention super high pressure (25 mpa) which you can only achieve if you have either lab equipement or a death wish. But they also figured out that 2.5 mpa was good enough to give satisfactory results. 2.5 Mpa is still aroun d 360 psi which is far beyond what I hope to do but it still shows us that increased pressure helps reach a higher level of polysaccharides in the extract.


3- Here is another study on the extraction of reishi with pressurized hot water extraction : https://pdfs.semanticscholar.org/042f/dc546c367bb1...

Please keep in mind that I have no background in chemistry of physics, this is all new stuff I learned in the last few days. There may be major flaws in my reasoning and I welcom you to point them all.

As it stands I figure that my best bet is to buy an antique pressure cooker that were built to withstand 35 psi of pressure(50 psia). The goal of this post is also to give a blue print to anyone who would like to extract medicinal mushroom at home.

Jack A Lopez
Jack A Lopez

2 years ago

By the way, have you ever seen a pressure cooker?


The reason I ask, is because that might serve as a pressure vessel, and they can be found at prices much cheaper than the example, used, pressure vessel you linked to.

Although I am not sure if a pressure cooker could withstand 55 psig (70 psia). I think the usual operating pressure, for a kitchen pressure cooker is about 15 psig (30 psia), and a temperature of about 120 C (which is the boiling point of water at 30 psia)

Also if you can find the kind that has vertical stub that the bell-shaped weight (regulator thingy) sits on, then I think that vertical pipe could serve as a way to connect pressurized air to the top of the pressure cooker.

I mean you could simply stick a hose over that stub, and put a hose clamp,


over the hose, for to seal it.

Also I think I already have all the parts needed for this; i.e. an old pressure cooker, an air compressor, plumbing fittings, a hose, a hose clamp, etc.

So, if you like, I could try putting those together, for to see if it explodes or not. Testing it at room temperature first, would probably be the most prudent way to do this.

Jack A Lopez
Jack A Lopez

2 years ago

If you want both high pressure (around 55 psi gauge, or 70 psi absolute, or 480 kPa absolute) and temperature less than the normal boiling point of water (100 C), I think the easiest way to do that is by pumping some additional air, or other gas, into the space above the water.

I mean, that is the usual picture inside a pressure vessel made to contain a liquid. There is liquid in the bottom of the container. Then there is gas, of some kind, in the space above the liquid.

In response to your question, "how do I get the water boiling?", the answer is you can't. The boiling point of water at 70 psia, is about 150 C.


You already said that 100 C, ordinary normal pressure boiling water, was too hot. So 150 C would be crazy. It would be absurdly too hot!

I don't know how hot you want the water to be. Maybe 50 C?

How do you do this? Well, you put it on the stove. Or put an electric hotplate under it. I guess.

Make sure not to exceed the temperature rating for the vessel, or the seals. I mean if the little rubber (or some elastomer) gaskets melt, then they'll blow out, and then you'll lose your pressure.

Regarding the question of how to add more gas, to the space above the liquid, well that depends on the nature of the gas.

If the gas is to be air, then use an air-compressor. Or a pump for bicycle tires.

If the gas is some kind of common industrial gas, like nitrogen, or carbon dioxide, or hydrogen, or helium, or whatever, then it probably comes in a bottle already under a pressure greater than 70 psia. Also maybe the bottle comes with a pressure regulator. From there it is just plumbing, I guess. This plumbing lets gas flow, from the gas bottle, through the pressure regulator, then to your closed pressure vessel, somehow.

By the way, you wrote the words, "Because studies have shown...", and this makes me wonder which studies you are thinking of.

If you could provide an actual reference, or a link, to one of these studies, that would greatly help those of us trying to answer your question.

I mean, the authors of these studies might have written some words about the details of how they were cooking mushrooms in a pressure vessel.