Carbon Dioxide- The Secret to Essential Oil Extraction

I was just studying a gaseous state module at my physical chemistry class and I couldn't help but ponder more about its applications like decaffeination of coffee but then it struck to me about how thermodynamic principles play a huge role in the field of perfumery as well, especially in the extraction of essential oils. 

                                  

That's when the supercritical fluid extraction using carbon dioxide caught my eye. And honestly, it's a huge game changer for the extraction of oils instead of the traditional modus-operandi of steam distillation which deals with piping-hot temperatures that could destruct volatile, fragile molecules like terpenes especially those belonging to the top notes. 

So, in order to prevent such incidents, SFE has been very useful because the temperature is maintained at low ranges between 32-60 degree Celsius. It gives out a highly concentrated and solvent-free extract which emulates the scent profile of the original raw material. 

There's myriads of isotherms (lines on the graph at a constant temperature) and we refer to them as Andrew's isotherms of C02 and he helped us prove that in real gases, if the molecules are cool enough, they would have a huge attractions that adheres to each other and attain the density like that of a liquid but also have the ability to flow like a gas- this was called as a supercritical fluid which could fly like a weapon of gas but with a thicker density/viscosity of a liquid!

So, we can notice that carbon dioxide behaves like a supercritical fluid above the temperature of 31.1 degree Celsius in the above diagram. We can highly pressurize carbon dioxide which selectively acts as a solvent to take out the needed components as it dissolves within it. And after that, carbon dioxide and the botanical oil pass into a separator where the pressure and temperature are reduced and then C02 converts back into a gas and leaves the remnants- the desired oil!

This is a very ecological, green method of extraction used for plethora of raw materials like bourbon vanilla, pink pepper, lavender oil, rose, etc. It's not toxic and odorless as well which doesn't add any other alteration to the odor and delivers the original raw material's scent in the form of a liquid. So, for the top notes, we'd need less pressure and we keep increasing it as we extract the heart and base notes accordingly...

Hence, this method provides us the realistic scent without hurting any part of it, somehow like a Xerox machine where the input could be dried lavender raw materials and the output would be fresh, soft, lovely lavender essential oil smelling just like the original input... 

Moreover, this method is more helpful than the steam distillation way because it can also trap non-volatile, heavier, complex resins as well like the sizzling piperine in black pepper or curcuminoids in naples yellow turmeric. It's a very efficient mode of extraction that swiftly blows like a blanket of a breeze- it sounds like magic: an ability to appear like an illusion of a light gas but soaks up the materials like a conjuring liquid...