Review: Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment (Liang et al., 2007)

There are many things about college I love, but almost none more than free access to an unlimited amount of academic research journals. Since the start of this blog, I have promised all of you that I one of the things I would do would be to read and review and summarize tea research articles for you. The post before last I gave you some very small tidbits, but this post I will go much more in depth and I hope you will join the discussion by commenting.

This article, Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment (see bottom for citation and reference link), is not the most interesting one I've ever read. What it ends up saying is that if you boil the fresh tea leaves for 3-5 minutes in the step before rolling and drying (basically replacing the pan frying or steaming part of making Chinese green tea), you can remove around 90% of the caffeine without removing the catechins (what we love about tea).

As many of you know, there is a very large and old witch tale flying around that says that if you boil tea for 30 seconds and then discard that, your tea will be decaffeinated. This study just goes to show again that this does not happen. At 1 minute at boiling of fresh tea leaves (not even what would qualify as green tea) only about 50% of the caffeine was removed while you need to reach at least 80% to be able to consider it decaffeinated. Greater than 80% caffeine removal only happened when the time reached at least 3 minutes at boiling water. (Don't forget that what happens to fresh leaves is different from what happens to any type of later processed tea leaves that we drink from too.) When they tried 3 minutes boiling on processed leaves (what could actually be counted as green tea), they found that the leaves were essentially decaffeinated. Unfortunately by then the cell walls were so broken that 90% of the catechins were also removed, therefore making your leaves useless and likely disgusting tasting. Did I really need to tell many of you that, though? Hahaha. I'm pretty sure that when you read "3 minutes boiling on (green tea)" many of you cringed and/or may have nearly cried at the thought like me. Hahahahaha.

So why does processing the fresh leaves into green tea change the amount of catechins removed? Catechin removal requires breaking the cell walls, which happens when leaves are broken by stirring during pan frying and definitely when rolled and dried. I wonder if this then means that there would be a significant difference between the amount of catechins released into the tea from something like Longjing vs. Gunpowder green teas though? Since one is very obviously rolled more than the other.

Another one of the points it makes in discussing how to decaffeinate the fresh leaves is that the water should be at boiling for decaffeination to happen. Somewhere below the boiling point (between 100C and 75C) the caffeine is no longer removed from the fresh leaf. In their table of results from this part (see Table 2), it's interesting to see that while that basically no caffeine is removed from the fresh leaves at 50C (the lowest of the tested temperatures), a significant amount of catechins are (~10% after 5 minutes). Because their study was about decaffeination as opposed to catechin extraction though, they did not test what happened in processed green tea leaves at these lower temperatures. It seems counter-intuitive to me that while normally catechin removal would require breaking the cell walls, brewing at lower temperatures before those steps also released them.

Even after processing the fresh leaves into actual tea, does do lower temperatures affect how much caffeine and catechins go into the water? Or are the cells so broken by then that there is no difference based on brewing temperature? Based on personal experience, I do believe that lower temperatures change the ratio of what goes into the tea since the taste is different. I just wish I had scientific evidence backing me up and explaining exactly what that taste difference was caused by. Maybe I'll find that in another article.

Reference:
Huiling Liang, Yuerong Liang, Junjie Dong, Jianliang Lu, Hairong Xu, Hui Wang, Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment, Food Chemistry, Volume 101, Issue 4, 2007, Pages 1451-1456, ISSN 0308-8146, 10.1016/j.foodchem.2006.03.054. (http://www.sciencedirect.com/science/article/pii/S0308814606002998) Keywords: Decaffeinated tea; Green tea; Black tea; Caffeine; Catechins; EGCg; HPLC; Polyphenol oxidase

Research tidbits! Yay!

I've told you time and time again that I swore I was going to do some "reviews" and summaries of some scientific articles, but just haven't gotten around to it. UNTIL NOW!

Quick update on my tea research obsession: I have 43 research papers on tea in my new tea folder. I've switched over to using gmail a lot more recently, and have found that I also really like using their storage space that sorts with folders and all those fun things and is really easy to upload and even work with online directly. All of these articles have to do with a lot of different things. Many have to do with caffeine, but honestly that's pretty much been said and done.

A lot of the new research coming out has to do with genetically analyzing the differences between cultivars, understanding what genes do what, figure out better compound isolation techniques, understanding compound synthesis and metabolism both in the live plant and in the final production of the different kinds of tea, and a lot about the anti-cancer and anti-viral properties of different kinds of tea. There is a lot I'd like to write about many of these, but some of them I need to do a lot more digging in to before I can ensure that I can convey everything about it with pretty much perfect accuracy.


Now to the tidbits~!
1) EGCG and all those catechins are catalyzed into becoming theaflavins and thearubigins in fermentation! 
2) Salt in the soil increases L-theanine in the leaves!
3) Puerh tea can help fight HIV!
4) You have to consume something like 10,000mg/kg worth of black pu-erh tea before any sort of toxicity appears. (Essentially something like several entire puerh bricks)

And next time I'm going to explore the effects of decaffeinating tea by hot water treatment on taste, based on the results from "Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment" by Liang et al., 2007.

Dang Seattle Rain and High School Graduations!!

My dear friends could not join me in any tea adventures today due to STUPID things like IMPORTANT HIGH SCHOOL GRADUATION HOMEWORK and DANGEROUS DRIVING CONDITIONS so there was no tea adventure. But I stopped by New Century Tea Gallery after service at my Choeizan Enkyoji Nichiren Shu Buddhist Temple to inquire at the very least about this year's spring harvest and found that the owner would be bringing it all back from China on June 1st! I'll have to stop in after that date instead then, which is fine and actually makes me pretty happy because then I get super fresh green tea! Woo!

In preparation for this I have broken in my beautiful new Kitani with a delicious Western Zhejiang Long Ding from Tea Trekker back in Northampton, MA. I need to drink all the Chinese greens I have up faster so that I can get more and have room for some Japanese greens too!! Hehehe. I'd really love to get some more Gyokuro, but I'm afraid my budget may limit me to Sencha. I love Sencha too, but oh my fluffy bunnies from the land beneath the bed, Gyokuro is just heavenly to me. So we shall see. It's also quite likely that I'll finally start experimenting with Matcha. Matcha is really great, I think, because I can just put it into a bottle and shake it up. Hahahahaha. Just like with putting a Chinese green into a Japanese tea pot I feel kind of sacrilegious, I also feel kind of sacrilegious for shaking up my matcha in a plastic bottle. Hahahahaha. But since I'm in college, I consider everything fair game.

And I swear to those fluffy bunnies again that ONE DAY I will summarize a few original research articles for you all here! On my list is Caffeine content, L-Theanine content and effects, and I should probably do EGCG too since everyone's always going on and on and on about that. But of course, I also want to focus on whatever cool things I can find out about Pu-erh or Purple tea. Maybe tomorrow.

I'm Such a Tea Geek

And I say that proudly! So many people go, "Oh, no you're not! You're a tea nerd! Not a geek!" as if geek is a bad thing, when I say it proudly. Hahaha.

But anyways, I just FINALLY got rid of my flighty mind by doing a bit of research on tea! I found 8 new articles that I was able to download and about 8 others that I had to request from the Five College Library. I hate UMass- Amherst. Apparently they have all the articles I want. But then again, if they were at Mount Holyoke, I would be the one who would have to go and find it and scan it, which would be a major pain, so haha for them I guess!

Some quick tidbits on the articles I found:

• L-theanine improves attention and task-switching, but it is not sure on the alertness part, and seems to be most potent in combination with caffeine!
• L-theanine may actually be highest in black tea! (Poor me, considering I hate black tea and it's quantity is significantly diminished in tea with lots of milk apparently too which is the only way I'd ever drink black tea hahahaha)
• L-theanine protects your liver!
• L-theanine helps schizophrenics!
• L-theanine helps significantly decrease smoking!
• THERE IS SUCH A THING AS ALBINO TEA!
• Black tea helps renal (kidney) transplant patients recover!
• And that kind of thing. There was much more. ONE DAY I will finally post summaries of all these articles up here, so that people from non-science backgrounds (and even those of science backgrounds but from non-biology disciplines) can have some extra excuses to justify their love of tea. Maybe I'll even get in to learning more about the biochemistry behind coffee and do comparative research. La la la one day over the rainbow... Hahaha.

Who am I kidding?

I don't know enough about aging pu-erh right now nor do I have enough money to go around amassing tea that I'm not going to drink. Hahahaha.

But either way, today I did something really funny. Haha. So yesterday I made spaghetti with friends. And with spaghetti comes marinara sauce! And with marinara sauce comes awesome glass jars with lids! Hahaha. And as every Northwesterner knows, mason jars make for great mugs! And today I have proven that they make great makeshift glass teapots too! Hahahahaha!

That's right! I made tea in a mason jar! Hahahaha! One of my filters for a tumbler fits perfectly in the opening of the jar, so I figured I might as well have fun and make tea in it too. Now I have a large teapot for my pu-erhs which I can't make too easily in my Breville! I love my Breville and all, but it doesn't really do less 30 second brews easily, so it's not the best for large tastings. I was thinking about getting a larger gaiwan (the one I have now is good for 4 people max and at that point your serving is super tiny), but I'm feeling protective of my wallet at the moment and would rather not spend even that much money, thus leaving me without a teapot bigger than 8oz! Until now! Hahaha! Now I technically have a 24oz teapot! Hahaha! I feel super hippie and college student-ish. It's lots of fun.

 Isn't it beautiful? Haha. That is also my new Mengku sheng in there too, just to let you know. And it was again a lot less spicy than I keep expecting it to be! Year 5 is definitely an interesting turning point for shengs I guess. Ah, I love this journey.

Oh and I found out something really cool the other day, apparently students can be instructors for classes during our intersession term in January! Hehehe. I was thinking of seeing if I could teach a henna class and a tea class. I know I'm not an expert on tea or a tea master, but I would absolutely love to be able to share my love of tea and what knowledge I have with more people so easily (and get paid! Haha). Plus then I'd have the funding and the excuse to buy more teaware and tea! Hehehe! But we'll see. I feel a little premature to start teaching other people about tea so seriously like that. So maybe I'll just stick with henna. What do you think? I was also really hoping to be in Japan for that winter break time period (we don't have to attend the intersession term), so maybe I won't do that this year... But again, we'll see. Hmm, I wonder if I could visit a tea farm when I'm there this time around! That would be so cool!

Speaking of Japanese tea, I'm considering learning Chado, because I really have a lot of respect for it and would also like to expand my Buddhist practice, but that's just an idea I have arbitrarily floating around right now, and I definitely don't have the time for that this year, and if all goes well and I get into the classes I need for next semester, I really won't have the time for the next 4 semesters either! Haha.

So I don't know if I've mentioned this on here before, but I want to be a biomedical researcher. I LOVE SCIENCE. You might have realized that by now. But really, I LOVE SCIENCE SO MUCH. Almost three years ago now I was extremely lucky and had the amazing opportunity to intern at a university hospital research center. Going in my intention was to explore the research side of medicine and confirm that I did not want to be a part of it. Haha! That's hilarious because I left with exactly the opposite mentality. I fell head over heels in love with research. I'm pretty sure I ended up working like 50 hours on average per week there instead of the required 40 because I stayed after almost every day and I even went in on weekends sometimes. I was extremely happy to get up every morning in order to go to work and didn't really want to leave at the end of the day either. Haha. It was just so exciting to go in and not know what you were going to find when the project was done. It was also really fascinating to learn hands on how cells and the chemicals in the body worked. Just thinking about it all makes me so happy and excited about it all over again! So I left knowing I wanted to be a researcher for certain.

To do this, I would preferably like the MD/PhD combo degree. If I can't get into that, then an MD, if not that then a PhD, and if I can't even get a PhD then I don't know how on earth I'm even alive. Hahaha. And it's not like I want just any MD/PhD degree either, I really want to get into one of the few NIH sponsored programs as well, because then it's F R E E. Woah! A 5 year doctoral degree, free!!! That would be a dream come true. So in order to even qualify to get in the first place, I obviously have to take care of some pre-med requirements. These requirements differ slightly from med school to med school unfortunately. I decided however, that Harvard's would likely be of a very high standard and am going off of theirs. I figure if I can achieve their standard, it will cover whatever requirements other med schools have as well.

I think I'm definitely right because they changed their requirements for the year I'd be entering (2016) this year, and basically added on an extra year of intensive physics classes and biology and chemistry classes. ...THANKS A LOT, HARVARD SHOWOFFS. Hahaha. Just kidding. I would've been taking most of those classes anyways, and they all look really interesting, so I'm sure it'll be fun.

So after figuring out which classes I'll therefore absolutely have to take I realized that I will qualify to basically be a Biochemistry major with a Physics minor. Hahahahaha. And not only that, but for the next two full years I will have to take at least one biology, chemistry, and physics class per semester. Technically I could put off one or another for a year and ease up the load a little, but I work better under a bit of stress and when I'm extremely interested in a subject. I feel that I definitely need to have a balance though, and so I'm trying to decide between Asian Studies, Economics, International Relations, or Buddhist Studies for my 2nd major or my minor. I'd rather do a double major instead of a minor (and I only need one music class to take care of my last distribution requirement because this year was so well rounded! Woot!) and I have like 13 class spaces that I could put whatever I want to in, more than enough for a 2nd major, so it's not like I won't have time for it.

But anyways, the future is certainly packed isn't it? Yup. And now I need to go do homework like usual. Hahaha. Time for more tea!