Tea Snobbery 101: Milk and Sugar are Evil
Note: I am not a believer in BadWrongFun™. I do not think that you are a bad person if you like things that I don't like. This is not a hit piece on your taste. But it might be a hit piece on your frugality. Read on.
A stellar tea described
As I sit here in my office, I'm sipping a lovely cup of 南京雨花茶 (Nánjīng Yǔhuā chá, Nanjing Yuhua tea). This is a famously subtle, light tea that needs patience to allow flavours to build up before they can be fully appreciated. When you first take a sip it's almost a disappointment. The liquor is pale like spring straw, and the taste is thin, almost watery. A hint of sweetness, a touch of nuttiness like chestnut, maybe a ghost of toasted pine. It's clean, cool, vegetal, and it vanishes almost immediately.
You could be forgiven for thinking this tea's reputation is grossly overrated.
But then you wait. You take a second sip a while later. And things have changed. The flavour is now clear; the thinness has fattened up. The sweet chestnut nuttiness now builds on a foundation; a kind of tingly basis on the middle of the tongue. The pine note has sharpened, giving ghosts even of dill weed: bright and resinous. And at the back of the tongue a strong umami note is beginning to build.
Sip after sip the taste develops. The sweetness transforms into a cooling finish that coats the back of the throat. The nuttiness develops into something stronger: think almonds, but raw, not roasted. The umami strengthens into something like a delicate vegetable soup's broth. Every sip layers over the previous, changing the flavour with each exposure.
This tea is not loud. It is patient and requires patience to appreciate. As you sit with it, patiently sipping, it shows off the molecules it arranges on your palate sequentially, one after another. The finish stretches for almost half a minute: a faint, sweet, yet astringent dryness that makes you reach for the next sip.
It's a tea that begins as nothing, but slowly, patiently, becomes everything. It is a true world-class green whose reputation is well-deserved.
...unless...
Unless, of course, you put milk into it. Or sugar. Because milk and sugar do to fine teas what the law at the end of Rush's “The Trees” does:
And the trees are all kept equal by hatchet, axe, and saw.
Milk in particular is the great leveller of tea. It is the hatchet, the axe, the saw, the chainsaw, and the forest fire that keeps all trees equal by force. If you're a fan of milk in tea, however, you likely won't understand this or believe it. So today I'm going to give you the science. And if you still want to drink your tea with milk and/or sugar (and there is nothing wrong with this!), I'll be saving you a lot of money in the bargain!
The lesser ruination
The addition of sugars to green tea has a direct, measurable negative effect on its “phenolic” compounds, the very core of its flavour profile. Sugar cuts away approximately 1% of the free radical scavenging activity of tea's phenols per 1% of sugar added. So you are, in effect, paying for a full symphony orchestra, but then smearing glue over the instruments that play the notes.
If you are the kind of person who brews the tea together with the sugar, instead of adding it afterwards, there's another effect that may come into play.
Tea brewing relies on diffusion. Flavour compounds move from an area of high concentration (the leaf) to lower concentration (the water). Dissolving sugar into the water changes the osmotic environment that the tea is diffusing into, subtly altering the extraction dynamics.
The result could be (the physics is sound, but there has not been any direct study of it in tea that I've seen) that fewer of the tea's volatiles are extracted. You have to make up for it by brewing for longer. And that causes the more unpleasant flavour elements to concentrate, ironically turning your tea more bitter because of the sweetener being present.
The greater bringer of devastation
Sugar in tea is ketchup on cordon bleu cuisine. It's a negative, but it doesn't stop the flavours from appearing. It merely reduces our experience of them.
By comparison milk in tea is a wrecking ball swinging through a garden shed. It leaves nothing worthwhile in its wake.
Let me explain.
At the heart of milk's devastation lies a class of proteins called caseins, which make up about 80% of milk's total protein.
These caseins form large colloidal structures known as casein micelles. Their surfaces are rich with proline residues, which have a unique affinity for phenolic compounds. And this isn't a weak affinity. It's robust, multi-point, non-covalent cross-linking acting through hydrophobic interactions and hydrogen bonding. Which is an appropriate pair of words to end that sentence on since the effect is vaguely like a hydrogen bomb in its impact on flavour.
The subtle complexity that forms the unique signature of each fine tea comes from tea polyphenols (TPP). When milk is added, the casein micelles sweep in and bind to these polyphenol compounds, effectively removing the “free” polyphenols from the tea infusion. This forming of larger complexes decreases the availability of free TPP. What is perceived as “smoothness” in the mouthfeel is, in actuality, the erasure of the fine-grained profile that gives the tea its depth and complexity. The tea's delicate astringency (the building block of that flavour development I described above) is chemically neutralized at the molecular level.
Even worse, the TPP-casein binding doesn't just affect taste perception, it also suppresses and traps aromatic molecules using the same mechanism. The aerial release of the many tea volatiles is significantly suppressed by the simple addition of milk; the very aroma of the tea gets locked up before it can ever reach your nose.
As a final kick in the teeth (yes, from a wrecking ball) there's some scientific evidence that the binding of caseins to tea flavonoids reduces their antioxidant capacity and potentially their bioavailability. So not only are you flattening the flavour of a fine tea and trapping its aromatics to reduce its lovely scent, you are also paying a premium for the bioactive compounds you're about to remove anyway.
Moneysaver
The tea I started with, Nanjing Yuhua, sells at time of writing for US$55 for third-grade tea to almost US$200 for the top grade per 500g (roughly a pound) at one randomly-selected online shop. And that's the grades you can buy outside of China. The very best grades, from specific sites, picked and processed by famed masters, etc. will sell inside China (basically unavailable outside) for an order of magnitude more. It's expensive, is what I'm trying to get across.
And the flood of casein assassins your milk has unleashed into it has taken everything that makes the tea worth that cost and removed it. Indeed it may have even reduced that tea to a quality that is lower than a robust cheap green (the kind of coarse, bitter autumn chop from unnamed plantations that sells for next to nothing). Even the lowest grade of the Nanjing tea is ten cents per gram, while the highest grade you're likely to get outside of China is almost half a dollar per gram. An autumn chop is fractions of a cent per gram. And with milk, the autumn chop might actually taste better. And sugar isn't much better. Maybe the sugared Nanjing tea will taste a bit better than equivalently sugared autumn chop, but it won't be two orders of magnitude better.
So if you really do like to drink your tea with milk and/or sugar (and again I have to stress: there is absolutely nothing wrong with this!), save yourself a lot of money and buy the cheap autumn chop. It will likely taste better, and the money you save on the tea could be put to better use buying some really nice silk wall scrolls or something.