This topic sparked some interest in the chat so I am reposting what was said in another thread.

Why should you try using a PC ?

1. More effective lysing of the cells due to higher temperature
2. Less volume to deal with, compared to usual boils
3. Less mess (you are using jars)
4. Faster than multiple boils

Also use rack so that the jars aren't touching the bottom of the PC. Alternatives for a rack.

Shroomery's PC guide.

nice

so of course, unlike cannabis (where the actives are outside the plant cells), the actives of mhrb are contained within the plant cells. shredding/pulverizing the dry plant material does not break all the cells, so other physical means may be implemented (sonication, PC, microwave, etc.).

This approach first dawned on me when a friend gave me five gallons of cactus goop to process (he thought he f'ed up a san pedro extraction). the swollen mass was nothing more than rehydrated cells, from san pedro powder.

Really glad to learn of this efficient method. Iam wondering why a "stainless steel" PC is mentioned as some are made of aluminum, including models from the Presto brand mentioned. There certainly isn't anything wrong with using an aluminum pressure cooker, correct?

Aluminum is very reactive with oxidative species, thus corrodes in contact with acids and bases.

Thanks for the answer Benzyme, but I understand this already....Iam confused because the
cooking is going on in the glass jars and not directly in contact with the aluminum or steel pressure cooker. What am I not understanding?

you're not understanding that the material is in an acidic phase, and some of that inevitably spills over into the pot due to pressure equilibrium; it's just something we have to deal with, leaving jar lids on loose.. because tightening them risks implosion of the the jars

Is using aluminum really that bad. I saw in another thread also the advise from benzyme to not use a aluminum coffee press. Thanks for that, I double checked if the strain was made from stainless steel.
So the aluminum can oxidize easily with acidic solutions.
Are these oxidations which can probably find their way in the final product really that bad for your health? And how is that manifested health wise?
Cola, which is really acidic, is normally stored in aluminum cans. Is that something to avoid as well health wise because of oxidation?

Maybe it's an idea to make a sticky topic in the extraction sections in which all potential hazardous reactions between tools and chemicals used can be listed so everybody can be directed to that checklist for safety precautions. Now all those advises are spread in several topics.
Things like:
Hcl and metals
Aluminium and acids
Plastics and solvents.
Pressure build ups in reactive phases.
Heat developments in certain reactions.
Fume developments.

Most pressure cookers are made of aluminum, unfortunately.. All American PCs and sterilizers are aluminum, and most Prestos or Walmart PCs are aluminum. Probably because it's cheaper and lighter than steel.

http://www.amazon.com/Pr...s-Pressure/dp/B00006ISG6

I have that one.
there are several others, larger ones. you just have to search.
stovetop autoclaves are basically stainless PC's, but they're typically $200-300.

I use a German Fissler model:

http://pressurecookerreviews.ne.../fissler-pressure-cooker

It is easy to use and its safety features give you great assurance you won't end up with a green ceiling.

The thing literally EATS cactus....one three hour boil = one 40 minute steam. Superb results. Gotta try with B. caapi ...
No problem with light acidifying with lemon.
Also, the core of the extra thick base is likely a layer of aluminum...pretty standard in high quality cookware bases around the world IMHO,

Wow here in "europe" you can´t get pressure cookers made out of alluminium. We recently bought one and looked arround, and all of them are made out of stainless steal here.. Think it has something to do with security, because alluminium may explode easilier than steel..

And yes Acid + Aluminium = Bad idea. And it is bad for your health. It is accused for alzheimer.

edit: Cooked HCL is used to color aluminium b.t.w. (opens the surface to allow colors to get into it).

Experimental

5,5 l (5,8 quarts) pressure cooker
700 ml glass jar (heigh - 12,5cm, diameter - 8,5cm) with a lid
60 g of MHRB
350 ml of white distilled vinegar (5%)

60 g of MHRB was put in jar and 250 ml[1] of vinegar was added [2]. Lid was loosly put on the jar which was then transferred to the PC that had a ceramic plate on the bottom [3]. 2000 ml [4] of tap water was poured in[5] the PC that was then closed, set on 121C/90kPa/13 psi and put on the stove on max. When[6] whe safety valve jumped out, the heating was reduced to a minimum. After 50 minutes the PC was taken off the stove and pressure was released[7]. Vinegar from the jar was decanted [8]. 2000 ml of new water [8] was added to the PC and 250ml of vinegar to the jar [9]. In total, three 40 minutes boils were done. Liquid from the three runs was combined, left overnight then decanted, basified [10], extracted with limonene and FASW evapped. 60g of MHRB yielded 920mg of fumarates [11].

Notes
[1] Roughly 4-5x more volume than the volume of MHRB. 2:1 (125 ml of vinegar) as intructed in the original TEK was also used but it produced just mush and not very much (just about 5ml) decantable vinegar.
[2] When vinegar is added secondly a lot of stirring is needed since on the first contact a lot of lumps appear and vinegar doesn't really mix well without if just poured in. A better way to do this is probably adding mimosa in small increments to the jar containing vinegar while stirring after each addition.
[3] Safety precaution to prevent direct contact between the glass jar and the bottom. This might prove itself not needed in the future.
[4] About 500ml is lost during each run. 2000ml was used because the safety limit on the particular PC is ~1500ml.
[5] Including the jar weight the whole water level was now at 2.5l.
[6] It took about ~13 minutes the first time. PC cooking begins now.
[7] Around 4 minutes for the slow release method.
[8] This also might not be neccesary since just the "lost" 500ml could be replaced
[9] Mix it a bit.
[10] 50g of NaOH. Overkill due to inaccurate pH meter.
[11] 920 * (73%) = 671.6 so max 1.1% (0.671/60*100) freebase yield.

What did we learn ?
- 2:1 is not a good vinegar:MHRB ratio. We should aim at 5:1 or moar.
- The procedure is extremely easy to clean since the PC is virtually free of any mimosa stains.

What is with all the rubber elements in the lid? Do they get influenced by the acidic steam? How much more yield can be expected in comparison to a normal boil?

it's not the polar solvents you need to worry about degrading rubber.

DidMyTest, since vinegar is used in the canning process I wouldn't worry about that.

The main advantage of this method is not so much yield increase but "less mess". You use less water, less gass, less time and there is less to clean. There might be other benefits but I haven't done enough testing to determine other possible benefits, such as yield increase.

In the UK its difficult to find one made of stainless steel, most pressure cookers are aluminium. Personally I wouldn't be that concerned with using an aluminium PC - indeed I do use one for other things - If everything's in jars there will be very little reaction with the aluminium, & nothing that'll get into the jars.
Just don't try to mix either acid or base directly in aluminium - I once had basified mimosa eat through the bottom of an aluminium pot. Learned that lesson.

There are loads of stainless steal PCs in pretty much any supply store in London. I've looked around and most places stock them.

Has anyone experimented with Freeze/Thaw lysing in combination with boil lysing?

Maybe a boil, freeze, boil?

Please be careful with pressure cookers. Don't used powdered MHRB as it could clog the relief valve. Thats why you cant pressure cook beans, the hulls can come off and clog it. then kablooey..

Aetherbound