This is a fantastic idea and one that I have been putting a lot of research and thought into. Pressure cookers are very popular amongst healthy eaters for cooking because they retain all the vitamins in meats, vegetables and ect. so why would it be any different for cannabis? Isn't Pot just a plant like any other?
Benefits:
No smell
faster cook time
zero losses
I have read comments by naysayers on other forums: people say it will burn the THC or dilute it because Pressure cookers get too hot but I haven't read a post by anybody that has actually tried it. Those comments are informative and may have some validity to them but they seriously lack any understanding of the physics behind how a pressure cooker works.
I would like to approach this topic from a purely scientific point of view (no experience yet). By raising the pressure of a liquid you raise the boiling temperature of that liquid... If you need proof of this learn how the pressure in your car radiator controls the boiling temperature of antifreeze or how an air conditioner works, it's Bernoulli's principle.
The THC is in a liquid form (oil) when it enters the butter so why wouldn't it exhibit the same properties? My guess is that the THC will no longer vaporize 225 (or whatever temp causes it to vaporize). Instead it will vaporize at a much higher temp as does water and every other liquid on earth. THC may be magical but I doubt it escapes the laws of physics.
Furthermore, it shouldn't matter if it does vaporize! It is in a sealed unit, it would only condense again when cooled. Simple chemistry says that it would condense back into a liquid form and be attracted to the butter: polar vs. non-polar chemical compounds, THC and fat are both Non-polar therefore they are attracted to each other. If vaporization does occur, according to this theory, it may in fact increase the potency.
Also, if you want to play it safe and odor while cooking is your concern; you can still have the benefits of no odor and cook your bud in a pressure cooker. A pressure cooker (stove top type) can be used without any risk of vaporizing THC. You just have to make sure you don't turn it up. Pressure cookers are capable of heating there contents to a higher temperature but you are in control of the amount of heat it gets. An IR thermometer can be aimed at the side of the pot to me sure you remain at your desired temperature. If odor is your only concern just don't turn up the heat. A pressure cooker will not blow off any steam if the temp is kept low (because it won't build enough pressure to open the valve).
Please, somebody tell me if I am missing something here. I think this will work famously but I am wondering if it is too good to be true.... maybe I am wrong about something here.