Why Your Tea Tastes Great, According to Science
It's taken centuries of extremely hard work to achieve the perfect brew.
Forget every stuffy, pinky-raising thing you thought about tea and look at the beverage in a new, nerdy light. This classic drink has a lot more going on when you break down what actually happens in the cup. That's right, it's pure science, from oxidation to fermentation to extraction. "There has been a great partnership between plants and people being fostered over the many centuries to make great tasting teas," says Mike Harney, co-owner of Harney & Sons Tea. "It was not science back in the day in ancient China. However now science can explain what was done and how that made your cuppa' taste the way it does."
What is tea?
The first thing to understand about tea is that it's a plant, Camellia sinensis to be exact. Most of the tea you will see comes in three forms: black, green and oolong. Yes, there are other variations too such as pu'erh, white, matcha, and herbal, but save for the latter which isn't actually tea, they are all derived from the same source. No matter the color of the tea it's all Camellia sinensis. The hue and flavor just come from how the plant is treated and where it grows. Oxidation also plays a part as it changes the chemical components in the leaves, something that helps make each tea unique.
"Green tea is fixed green by steam or direct heat; oolong is slowly oxidized; and black tea can be made with fast or slow rates of oxidation. It is a question or particle size, cell rupture, and oxygen availability," explains Harney. From there, he says, you can do all sorts of things to the tea depending on how it's handled, how long it gets oxidized and what shape the leaves are put into. "The slower the oxidation, the more interesting aroma chemicals are developed. In fact in Taiwan, they put tea in an air conditioned room to slow the rate down."
No matter the type of tea, you will usually find it done using a traditional or orthodox method that involves plucking the leaves, withering them, rolling and allowing the plant to oxidize and/or ferment as it dries. The other process is called cut, tear, and curl, and is only done to black tea. With this style the leaves get passed through cylindrical rollers with serrated blades that turn the tea into little pellets. This form is particularly popular in the United Kingdom and India where they like their brew bitter, dark, and perfectly suited for milk and sugar. Traditional loose-leaf tea will steep differently and, as long as you don't let it sit in the water for too long, creates a pleasing beverage that doesn't need any enhancements to make it palatable.
How tea gets its flavor
"Scientists have identified over 700 chemicals in those tiny leaves," says Harney. "However, we humans can not notice all of them, so it is a question of which chemicals your nose knows." Yup, you taste tea not with your tongue but with your nasal receptors. This unique fact comes thanks to Richard Axel and Linda B. Buck, two scientists who won the Nobel Prize in Physiology or Medicine in 2004 for "their discoveries of odorant receptors and the organization of the olfactory system."
While the nose does the brunt of the tea tasting, it's the actual plant and all its polyphenols, amino acids, enzymes, pigments, carbohydrates, alkaloids, minerals and volatiles giving off the aroma. This can change depending on where it's grown and how it's handled. For example, Chinese tea makers tend to slowly oxidize the big leaves in order to develop wonderful smells like cocoa and rose. The green tea called sencha gives off a grassy and vegetal sense; tai guan yin oolong offers creamy floral notes; and black tea from the Yunnan province in China tends to produce a honey and/or chocolate essence. You will also find added scents and flavors when blenders put in bits of fruit, flowers, and even toasted rice, which causes the tea to taste like those components. Fermented pu'erhs can have mushroom and earthy tones, and lapsang souchong gets its campfire aroma from actually smoking the tea leaves.
Why water temperature matters
If you have ever looked at a box or bag or tea you may have noticed it calls for a certain temperature in order to properly prepare the drink. The reason for this select heating is to create kinetic energy so the solids of the tea can dissolve and release the tea's nuances. If the water temperature proves too high it can scald the leaves and lend a bitter taste. Of the three main teas, the tender green needs the most love and low steeping temperature, about 170 to 185 degrees. Black tea, because it's oxidized longer and has heartier patina can be brewed at a full boil. Oolong falls in between the two and should be steeped at around 180 to 190 degrees.
The amount of time your tea spends in that bath also factors in. Since green proves more delicate you want to only let it soak for about two to three minutes so it doesn't turn tannic. Both oolong and black tea can steep for three to five minutes, depending on the quality of the leaves. Don't fall into the idea that letting your tea soak longer will create a bolder cup. Instead, it will make for a beverage no one wants to drink without a ton of sweetener and sugar.