A cup of tea is a stew of component chemicals.
In the 1-2% that isn’t water, you’ve got your polyphenols, caffeine, amino acids and other nitrogenous compounds, vitamins, and minerals/inorganic elements. This is not to mention the lipids and carbohydrates (sugar and fiber) that largely don’t infuse from the leaf, but can still wind up in your mouth. Oh, and I forgot the aroma compounds.
So to analyze and understand the taste of tea, I got my hands on some of the separated component chemicals.
First was theanine. It’s the predominant amino acid in tea, and is only found in tea with some small exceptions. It’s often said that theanine contributes the brothyness or mouthfeel to tea. You may know it as umami, the fifth basic taste.
(The second-most prevalent amino acid in tea is glutamic acid. That’s the source of MSG, monosodium glutamate, the notorious flavor-enhancer rumored to cause Chinese-restaurant-syndrome. Maybe that gives you an idea of what theanine might taste like.)
So when I mixed this theanine with water, I was expecting to taste soup. I put maybe .15 grams of this white powder in .5 fl oz of filtered water and stirred it up with the tip of a knife. (It dissolved in laminar swells, like icebergs calving or tectonic collision.) It had a slightly slippery mouthfeel, but not as thick as I was expecting. Alison downed the rest of it and said it tasted metallic like seltzer or baking soda, with a hint of cucumber. I agreed, but I had a hard time explaining how the elusive plant flavor was unstable like fish, but inorganic like metal. I decided I was really going to figure out this flavor, so I mixed up about .3 grams in the same little pinch bowl of water. That was crazy. There were sensations moving around my mouth, spreading from the front the sides, and I gagged. I decided to come back to it later.
We tried the polyphenols next. They say polyphenols contribute to the astringency of tea. I had an extract of ≥80% tea polyphenols, with <1% caffeine. (≥45% epigallocatechin gallate, guaranteed!) It was a fine reddish powder that looked like brick dust. It smelled like brick dust. I mixed about .2 g with 1.5 fl oz, and it tasted like I was hit in the mouth with a twenty pound sack of brick dust. (See pictures above.)
After spitting it out, I characterized the flavor as intensely bitter coffee grounds, with a smoke aspect lacking depth. There wasn’t any room for depth. It was dirty chalk mouth all the way across. Alison said she could tell it was over-steeped tea, albeit the cured ham variety. We tripled what was left with water, and the flavors of coffee and cigarettes were more discernible, having been previously masked by revulsion. We doubled what was left with more water and nuances of chalk and burnt log emerged.
Caffeine is said to contribute a bitter taste, so I tried another polyphenol extract that had caffeine still in it, <20% of the mixture. It tasted much the same. I convinced Paul to drink it and he said it tasted like strong tea. I should have known not to expect hyperbolic language from Paul.
I had read that polyphenols, amino acids, and caffeine are the main flavor components of tea. Yet after I drank them I felt like there must be much more going on. I guess when scientists refer to flavor they mean distinct from aroma. (There are tons of aroma compounds kicking around, and new ones are discovered every day.) Otherwise I’d be forced to conclude that there’s a whole lot of complexation going on when the three flavor components are mixed, and I don’t want to do that because I’d have to put them in my mouth again.