Monday, November 21, 2011

Flavors Sinking to the Bottom of the Cup, and Stirring Tea

Pictured here is the bottom of a cup of black tea:

One thing that I've noticed while drinking certain teas is that certain flavors and qualities of a tea tend to sink to the bottom of a cup. This is less of a problem when using a relatively short, wide cup like the one pictured above, and even less of a problem when using smaller teacups like those more commonly used in China and Southeast Asia, but even with these small cups, this phenomenon can occur.

What exactly sinks to the bottom of the cup?

From my own experience, I've found that flavor, more than aroma, tends to sink to the bottom of the cup. The bottom of the cup of tea tends to be stronger in flavor, more bitter, more sour, and to a slight degree, also sweeter. Astringency also tends to concentrate at the bottom of the cup. However, there are a few unusual teas in which I've found aromatic qualities sank to the bottom of the cup. One such tea was Huo Shan Yellow Buds (Huoshan Huangya) from Upton Tea Imports, in which the bottom of the cup had hints of olive and wine which were totally absent from the top of the cup.

For some brief science, tea contains both dissolved chemicals and suspended solids. Dissolved solids leave the tea transparent, whereas suspended solids are visible if you look closely enough, and from a distance, contribute to an opaque or cloudy visual appearance to the tea. Suspended solids only stay in water because the water is moving; if the water does not move, they will eventually settle to the bottom (imagine the green dust left at the bottom of a cup of sencha). Truly dissolved chemicals do not sink to the bottom of the cup once dissolved: they remain dispersed equally throughout the liquid. However, as the amount of mixing in a cup of tea, especially a tall cup, can be limited, dissolved substances still tend to be unequally distributed throughout the cup. This is particularly true (terrible pun here) when there is a lot of suspended particulate matter, small pieces of tea leaf, at the bottom of the cup, as dissolved substances are continually leaching or infusing from these tiny pieces of leaf.

In general, you tend not to taste suspended particulate matter, and rather, only taste things that are actually dissolved. So what is going on here is that suspended particulate matter, tiny pieces of tea leaf, concentrates at the bottom of the cup, and then various flavor components infuse from this matter. You might think that the cloudy or opaque teas would be more likely to exhibit the flavor-sinking quality, and I've found this true to some degree, but there are exceptions, like Two Leaves and a Bud's Darjeeling First Flush, which produces a very clear cup, and yet still has much of the flavor sinking to the bottom of the cup. I suspect that much of the particulate matter is so small that you cannot see it, but that it is still not truly dissolved.

Teas where I find some of the flavor sinks to the bottom of the cup:

For examples of this phenomenon, I've found that while drinking Dragon Well from Novus Tea, the flavors (bitterness, sweetness, etc.) tend to sink to the bottom of the cup. In the Formosa Amber Oolong (TT55) from Upton Tea Imports, I found a sourness sank to the bottom of the cup. A black tea in tea bags which I reviewed recently, Vienna, from The Foreign Office, had a strong bitterness that sank to the bottom of the cup.

I also find this phenomenon happens with herbal teas. For example, I find that when brewing Monarda sp. (bee balm, wild bergamot, oswego tea, etc.), a lot of astringency tends to sink to the bottom of the cup. The same phenomenon occurs, although in a less pronounced fashion, with other mint-family plants. I definitely notice it, for instance, with orange mint.

Stirring Tea:

If you drink tea from a larger cup, especially a taller mug, and you find that you don't like the fact that certain flavors or aromatic qualities tend to sink to the bottom of the cup, you can just stir your tea. But I don't necessarily always want to make my tea more uniform. Sometimes there is something pleasant about enjoying the different facets of a cup of tea...the fleeting, transient aromas at the top, leading into bolder flavors at the end.

Stirring your tea is something that most people associate with the addition of milk or cream and/or sugar, but it is something that I find can be helpful even if you drink your tea straight like I do.

How about you?

Do you ever notice that certain qualities in your tea sink to the bottom of the cup? Do you like or dislike this phenomenon? Do you stir your tea because of this? Do you seek out taller cups, or smaller ones, to magnify, or minimize, this phenomenon?


  1. This is a thoughtful post, and I really think you have your finger on something real here.

    But there’s a confounding factor you haven’t mentioned: obviously the tea liquor you drink from the bottom of the cup is the part that has had the longest time to develop.  Tea liquor is a complex mixture even without the particulates, so why wouldn’t it continue to change chemically, especially at warm-to-hot temperatures?

  2. Yes...I think it probably does change chemically. The bottom of the cup tends to be cooler too, because convection brings hot water to the top of the cup, so it would probably develop more slowly.

    Actually, I was thinking about this more and I realized another factor too, which is that the volatile organic compounds would escape more quickly from the top of the cup. This could explain those unusual teas like the yellow tea I sampled where the bottom of the cup was more aromatic.

  3. Alex: I tend to agree with Lew. I've noticed something similar, which I call the "second-cup phenomenon." It seems that with most teas I drink, the second cup in a pot of tea (not the second infusion, but the second cup of a single, large infusion) tastes better and more complex than the first. I noticde this particularly with second-flush Darjeelings.

    I once read a scientific paper about this-- and sad to say, I have never been able to find the paper, even after much looking-- which described in detail how over time, in a cup of tea, substance a will combine with flavinoid b, creating substance c, which then combines with a, making d, and so on. Heat + organic chemistry + time = more and more complex chemicals to taste and smell. I think that as you go from the top of the cup to the bottom, you're noticing the new organic substances that are being produced in the cup while you are drinking, which weren't even there at the start.

    Not to say that there can't be a greater concentration of flavors at the bottom because of settled particulate matter, but I tend to think the General Second Cup of Tea Theorem may explain it better.

    After much experimentation, now when I make a great tea, I'll take a sip of that first cup to see where it is, then usually let it rest for a few minutes-- not to cool down, but to skip that less-flavorful first cup and go straight to the "second".