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Using a pressure cooker for butter/oil extracts

Discussion in 'Cooking with Cannabis' started by fft, Aug 26, 2014.

  1. fft

    fft Well-Known Member

    Messages:
    47
    I'm a fairly new FC poster and not-so-new lurker. In a recent post I mentioned that I use a pressure cooker for making cannabutter/oil but later realized this is something I've never seen discussed on a forum. So I thought I would detail the method here... I welcome any comments / suggestions on how to do this better since I came up with this on my own.

    I am pretty serious cooking enthusiast (as well as a "budding" vaping enthusiast). The inspiration for this recipe is from Modernist Cuisine, specifically this recipe for Garlic Confit. Here's a snapshot of that recipe.

    [​IMG]

    After making this recipe which is amazing and also fairly simple, I thought the recipe could be adapted by substituting fresh weed or ABV for the garlic and clarified butter or coconut oil for the olive oil. You put both in a mason jar and put the mason jar in the pressure cooker. If you are going to make this, its worth checking out the Modernist Cuisine recipe page as well as this video which both show the recipe plus important basics on how pressure cookers work and pressure cooker safety.

    Why a pressure cooker? The chart below from Modernist Cuisine shows that you can control the temperature you are cooking at by controlling the pressure inside the cooker. It allows you to use water / steam above the usual 212F.

    [​IMG]

    By cooking inside a mason jar at 1 atm, I can cook the butter/oil at a constant ~250F. At this temperature for the right amount of time, I should not need an additional decarboxylation step. Also because the jar is sealed none of the lower-boiling terpenes, etc can escape into the air, as they can when you decarb in an oven.

    So anyway, today I made a batch using ABV and clarified butter. Here are the steps:

    1) Here is what I started with. 25g of ABV, a mason jar, my pressure cooker, and some soy lecithin. Sometimes I will grind up the ABV in a coffee/spice grinder but didnt feel like it today.
    [​IMG]



    2) Then I made some clarified butter.

    [​IMG]

    3) I added the ABV to one mason jar, covered it with (slightly cooled) clarified butter, and added a few drops of lecithin. Since I knew I was going to post, I weighed everything. It ended up being 215g of clarifed butter and 8g lecithin. Often if I have butter or coconut oil premade I will add it in solid form.

    [​IMG]

    4) Then I put the lid on (leaving it a little loose to let pressure buildup escape ... see Modernist Cuisine article for details), put the jar in the pressure cooker, added water halfway up the jar, then closed the lid.

    [​IMG]

    5) Got the PC up to pressure at 1 bar / 15 psi. Set a timer for 45 min at this pressure / temp combination. I'd be interested in others' thoughts on time / temp. My logic was to follow the decarb charts from 1990 that everyone seems to refer to, recognizing that it would take extra time to heat up everything inside the jar to temperature.

    [​IMG]

    6) After 45 min was up, I used the quick release (faucet) method to cool things down quickly. I then opened the lid and took the jar out with a potholder. After letting it cool a little more I opened it up:

    [​IMG]

    7) Then I strained everything into a silicone bowl and put the butter in the freezer to cool. I use a 100 micron "superbag" to get a fine strain. I suspect those of you that own bubble bags could use one of the finer mesh bags to do the same thing. Or just use a fine strainer. Or dont filter at all for that matter. I squeeze the bag a little to get as much liquid out as I can, but I know I am leaving quite a bit of potency in the bag. Licking your fingers at this point is recommended, but be careful since the butter is very concentrated and its easy to get very toasted very quickly.

    [​IMG]

    8) After a few hours I take it out of the freezer and snap out the "puck" of ABV-butter.

    [​IMG]

    I then vacuum seal mine, weigh it, and put it in the freezer until I am ready to cook with it. Today's puck was 134g, which is a little more than a stick.

    [​IMG]

    This ends up being a pretty concentrated butter that I then use for caramels. My goal is to get something handheld, stealthy, and shelf-stable that has a full effect with one decent sized caramel.

    Here's what I think are the advantages / disadvantages of this method:

    Advantages:

    1) No need to decarb separately.
    2) Good temp control of process at ideal temp for decarb / extraction
    3) Less cooking time than stovetop due to higher pressure extraction
    4) Sealed jar minimizes leakage of volatile compounds normally lost during decarb / extraction
    5) A pressure cooker can cost about the same as say, a magic butter machine, but its a multi-tasker in that you can cook lots of great regular food in it. I do risotto, refried beans, stews, chili, etc. In this regard a pressure cooker is much more stealthy in the kitchen than a dedicated machine for cannabutter.

    Disadvantages:

    1) Pressure cooking can be dangerous if you dont know what you are doing. Not that its unsafe or unmanageable, but anyone doing this should read up on how to use it and not leave it cooking completely unattended. Watch the MC video as a starting point.

    2) If you dont like to cook or dont want to deal with a stove/pots/pans, something more turnkey like a magic butter machine may be a better option.

    3) There's a risk that if you leave it cooking for too long at 250F, your THC will all turn to CBN. Now I originally started out cooking mine for two hours as with the garlic confit recipe. I thought it was pretty potent but have recently been cutting back the time for optimal results. That said, I also do a sous vide process where I decarb in advance and since the temps are lower (180-190), there is less risk of degradation there.

    4) There is no agitation / stirring inside the mason jar when its cooking (magic butter machine wins here). I think its extracts nicely as is but theoretically more agitation should result in a better extract. I shake the jar before putting it in so that the butter and plant matter are well mixed.

    Hope this is interesting / useful and would welcome thoughts/suggestions.
     
    Last edited: Aug 26, 2014
  2. MinnBobber

    MinnBobber Well-Known Member

    Messages:
    436
    This method is interesting.
    - when you first mentioned sealing the mason jars I freaked. Later you explained with the covers loose so pressure can escape. OK
    - I don't see the point in trying to lessen the time it cooks. You mention for better yield but I'd cook for an hour at the 250 F to make sure it's all decarbed. I don't believe that cooking it longer at only 250 F will turn any more THC into CBN. The longer it cooks, the decarb should have happened but longer time also allows for more goodies to permeate the butter.
    That's why at room temp, some let the herb soak for days---for full extraction.

    Good post , good pics. good idea
     
    fft likes this.
  3. Puffers

    Puffers Micro-Climate Mastermind

    Messages:
    1,026
    Location:
    Cali, Bay Area
    Great post and I like the method. I would be interested to hear others report on time and temps too. I would probably go low and slow myself but it sounds like your getting great results. With the lid cracked and those high temps aren't you not really capturing those lower temp volatiles that could be boiling off?

    @MinnBobber
    Is probably right about the CBN it's probably not a big concern in the time and temp ranges used here.
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921171/
    This study notes that CBN degradation tripled with higher heat but that was with temps over 325 degrees Fahrenheit and closer to the 400 degree range. Those are vaping temps :lol: now an interesting topic might be does it degrade rapidly enough in that 390 degree range that we can alter the CBN content by starting a session at high temps.....

    Any way thanks for posting and keep us updated.
     
    fft likes this.
  4. fft

    fft Well-Known Member

    Messages:
    47
    Thanks for the feedback and encouragement.

    I'll address the easier comment first - if the lid of the jar is cracked a bit how do I know that the lower temp volatiles are staying inside? I dont know for certain but my feeling is that not much vapor is escaping out of the mason jar, and even if some is escaping its not much. As @MinnBobber points out, the classic advice for canning in mason jars is to tighten the lid completely, then loosen it by a quarter turn so that if any pressure builds up it will be able to escape. I follow this advice too even though I'm not 100% sure its necessary. In this case I have a mason jar 2/3 full of clarified butter, and outside the jar I have water. As the temperature increases in the pressure cooker, the water is trying to convert to steam and is increasing the pressure outside the jar. Meanwhile, inside the jar, the clarified butter (which has very little water in it) should not be producing much vapor or expanding much. If it does expand there is plenty of room in the jar. So the pressure differential should be trying to push vapor into the jar, not out. That said, the way those lids work I am not sure anything is getting in at all. If vapor was pushing out of the jar (which happens in most canning applications like jam for instance), when the PC cooled down a vacuum should be created inside the jar to seal it (which is what those lids are designed to do). In my case, the jar lid is still loose when things cool down which makes me think not much vapor was able to escape. Also, there is very little smell until I open the jar. I'm not saying that absolutely nothing is escaping, but I have to think its a huge improvement over cooking uncovered.

    In terms of the temperatures, I would love to have a broader discussion on time/temp too. The reason I stop at 45 min is this chart that everyone references:

    [​IMG]

    On one hand this was a Russian study done in 1990, on a glass plate using a n-hexane solution in an open/dry environment. I wish someone else would try to replicate it in a more practical, butter-cooking environment, but surprisingly it hasn't happened. On the other hand the curves do make sense. At low temps you have decarboxylation only, with more efficient conversion at higher temps. But at higher temps the THC concentration starts to peak presumably because it starts degrading into CBN. At very high temps the degradation rate starts to overtake decarboxylation. Since I get a pretty good extraction after 45 minutes, I have just been saying better safe than sorry and stopping there. @Puffers paper is very interesting, but it just shows that under different conditions (in this paper when the THC is incorporated into a polymer matrix) you get different results. I cant tell reading the paper whether the temps are peak temps or if the temps were held for 75-90 minutes. But its not just these two papers... everywhere I've looked the information on both decarb and THC->CBN degradation temps/times seems to conflict. Its probably a different thread, but if anyone wants to launch a new thread to sort out all of the competing information, I would be an eager contributor.
     
    Egzoset, 215z and Puffers like this.
  5. MinnBobber

    MinnBobber Well-Known Member

    Messages:
    436
    Looking at the two charts, pressure cooker psi/temp and your THC content chart:
    I would consider using the 0.5 bar pressure for a temp of 234 F as the magic decarb temp
    is 220-225 F. The lower temp would likely have less of the good compounds transformed IMO.
    I'd do 234 F for 60 or even 75 minutes, allowing more time to soak out the goodness into
    the butter.
    ?? It looks like the pressure relief valve has different settings so you can adjust the pressure/temp, correct?

    Also, my confidence in the THC content chart is iffy....
    And, you're sure 1/4 turn backed off makes for a non airtight seal? I don't can so just askin
     
  6. fft

    fft Well-Known Member

    Messages:
    47
    I think 234 would be an interesting temp to try. It would be easy to monitor - on my PC 234/0.5 bar corresponds to that first red line on the stem (see pic above) rather than the second one that I used yesterday.

    On the seal, nothing is positive and I am sure there is some kind of leakage, but small compared to any other method I've seen. Keeping the lid a little loose like that functions more as a pressure escape valve than an open conduit between the inside and outside of the jar. Those two piece lids make it hard for vapor to escape into the jar - if pressure is higher outside the jar than on the inside then the jar is effectively sealed.

    As I mentioned, I also do a sous vide where I seal it up in one of those vaccum bags and put in a water bath at 190F. But those bags dont work in a high er temp PC environment so at 190 you still need a separate decarb to get a good conversion (if you believe the chart that is). Coming up with another way to do a reliable temp-controlled decarb that doesnt lose vapor would be a big step forward in my book.
     
  7. fft

    fft Well-Known Member

    Messages:
    47
    Here's another idea I'll throw out. That MC site mentions using something called a retort bag instead of a canning jar. A retort bag is one of those foil laminated pouches you often see in commercial food applications:

    http://en.wikipedia.org/wiki/Retort_pouch

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    They are sold on eBay...

    http://www.ebay.com/itm/125-RETORT-...r-Vacuum-Sealer-Packer-MiniPack-/370797994049

    ... and you need a chamber vacuum sealer to use them, which can get pricey quickly. I have a chamber vac but mine is more of a low-end pro-sumer model and this ebay seller calls my model out specifically as one that does not create a strong enough seal to use reliably.

    This approach might be too hardcore for even me. That said, I thought I'd mention it because if I were making infused butters / oils on a semi-commercial scale, which I am not, this could be the way to go. It would probably also work for Glycerin tinctures (which I've made in a canning jar before), but I'm not sure if it would be safe for ethanol. I imagine that the sealed pouches would be highly shelf-stable, especially with coconut oil which can go rancid quickly at room temps.
     

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