Sciencemadness Discussion Board

Theanine extraction from tea leaves

ThoughtsIControl - 23-5-2020 at 17:09

L-theanine is an amino acid that is found naturally in green and black tea leaves. What I found cool about this molecule is that it has been shown to promote learning and memory in numerous studies.

I plan on buying a pound of tea leaves in order to try and extract L-theanine.
If there's anyone out there who has done this or has some advice to give then I'm all ears.

ThoughtsIControl - 26-5-2020 at 05:37

Welp we're a few months into the coronavirus. As a student living at home I've got it set. I deliver food during lunch and dinner. At the same time I also have been teaching myself a big deal of organic chemistry and even some biochemistry. Lecture after lecture after I've listened to. I was so ignorant before at how little I knew. I hadn't even a clue.

Since I haven't had an answer on the OP, if anyone has recommendations for a good lecturer to listen to somewhere on the internet, then I'd love to hear!

Belowzero - 26-5-2020 at 06:14


This should be a good start.
Its from this document:
http://www.ajihealth.com/assets/-13_j-sci-food-agric_vuong_2...
Quote:

Of the tea components, theanine exhibits a higher water solubility
(385 g L−1 at 0 ◦ C, 556 g L−1 at 100 ◦C) than caffeine
(21.7 g L−1) and the catechins (e.g. epigallocatechin gallate,
5gL−1); this permits a very effective diffusion of theanine from tea
during hot-water infusions.2,40 The relative insolubility of theanine
in organic solvents such as methanol and chloroform (Table 2)
allows for its easy separation from caffeine and the catechins





Since its high solubility compared to the other components it should be relatively easy to crystalize the unwanted components out.

One could wash with methanol first to extract unwanted compounds from the leafs.

Then extract with water , boil down the solution and remove the unwanted product.

Then simply boil down the solution bordering the solubility of theanine and let it crystalize out at low temperature.
You can repeat this step to purify the product and conduct a meltingpoint test.

It's melting point according to wikipedia is 174 degrees C, perhaps thermal destruction or boiling away unwanted products could improve purity too.


Also this patent has some interesting details about extraction:
https://patents.google.com/patent/US5879733A/en


I've never done this and this is just what comes to mind, i'd be interested in your results/findings.


[Edited on 26-5-2020 by Belowzero]

Syn the Sizer - 26-5-2020 at 10:55

If you evaporated the methanol dissolved the residue in water you may also be able to extract caffeine with DCM as a second project.

ThoughtsIControl - 28-5-2020 at 19:55

Thanks for the feedback guys! I've ordered 2 pounds of green tea leaves and I plan on trying to find out the most efficient method for extraction. I'm thinking that I will first add water to the leaves to extract the L Theanine. After I filter and set the amino acid off to the side, I will try both methanol and chloroform as a solvent for the caffeine.

Is it safe to consume caffeine after extraction via methanol or chloroform? I'd assume that it is.. But as an amateur, I'd like to be sure.

Syn the Sizer - 28-5-2020 at 20:46

Quote: Originally posted by ThoughtsIControl  

I'm thinking that I will first add water to the leaves to extract the theanine. After I filter and set the amino acid off to the side, I will try both methanol and chloroform as a solvent for the caffeine.


Even with its low solubility in water the caffeine will come out with the water too. If you are looking to isolate the 2 compounds I would do as Belowzero suggested and do a first wash with methanol. This will leave the theanine in the tea leaves, follow this with a water wash to extract the theanine.

According to this paper theanine is insoluble in methanol and chloroform so again I would strongly suggest making your life easier extract theanine with an organic solvent like methanol or chloroform than extract the caffeine. Either way you need to figure out a way to isolate the theanine from all the other compounds. In fact this paper I linked is called

"L-Theanine: properties, synthesis and isolation
from tea by Quan V Vuong,∗ Michael C Bowyer and Paul D Roach"

If you are doing an initial wash with water than trying to extract the caffeine from that use chloroform or DCM. Due to methanols miscibility with water it would be a poor solvent to use. In class we used H2O to extract the tea leaves, than we did a couple washes with DCM to extract the caffeine from the aqueous layer.
Quote: Originally posted by ThoughtsIControl  

Is it safe to consume caffeine after extraction via methanol or chloroform? I'd assume that it is.. But as an amateur, I'd like to be sure.


This is all on your confidence, where you sourced your reagents, what you did the reaction in.

I once did a search for food-grade solvents and found this website.

I would not use my chloroform I made in my lab to extract anything for human consumption because I would be using an OTC source of ClO- and OTC source of methyl ketone, acetone or MEK.

I would not use my glass ware because I have used it for copper, nickel, among other stuff.

Now lets say you used a food grade solvent to extract caffeine from tea or even theanine for that matter and used either new glassware or glassware only used for edibles. It now comes down to do you trust yourself to purify the substance and remove ant solvents or other contaminates that may make you sick.

If all of those factors are taken into account and you are more than confident in all of your steps than it is your call. Nilered had made few edible chem videos and consumed his products.

[Edited on 29-5-2020 by Syn the Sizer]

Syn the Sizer - 29-5-2020 at 04:56

I should also mention methanol is miscible in both DCM and chloroform so you cannot extract caffeine from methanol like you would from water with those solvents. you would need to evaporate the methanol and redissolve in water then do the organic extraction.

ThoughtsIControl - 31-5-2020 at 07:34

Thank you guys for all the comments. You are all very helpful. Also, I'll be very careful about contamination when I plan on consuming the extracted products.

"According to this paper theanine is insoluble in methanol and chloroform so again I would strongly suggest making your life easier extract theanine with an organic solvent like methanol or chloroform than extract the caffeine. Either way you need to figure out a way to isolate the theanine from all the other compounds"

My tea arrived today! So, as soon as I get my hands on some methanol --> I will do a wash to extract the caffeine. Then, I'll evaporate the methanol as suggested. As soon as my filtered solution is dry, I'll rinse some water in it to extract the l theanine. This, too, I will let dry.

This simple procedure should give me a fairly good yield on both the caffeine and the L Theanine. I'll be sure to let you guys know how it goes!

Syn the Sizer - 31-5-2020 at 11:23

Awesome, I would definitely like to know how you made out with this project.


Edit:
After evaporating the methanol, you will want to dissolve the residue in water too, this will make the organic extraction of caffeine a little easier than trying to dissolve it right into the chloroform or DCM.

[Edited on 31-5-2020 by Syn the Sizer]