Tea and chemistry

Late December 1998, a Nepalese winter. We climbed the steps of Swayambhunath Stupa, a famous Kathmandu temple known for its painted eyes and monkey residents. There, I had tea served by monks.

Had our first taste of milk tea and butter tea in the temple. Milk tea is this beautifully smooth, sweet tea, which although seems like normal English tea with a bit more milk and sugar, has yet to be emulated back home. Butter tea is the equivalent of salty tea. Since I didn’t like butter in the first place, it was cringeworthy to drink it. I managed to finish the whole cup though I know most others didn’t.

It was only decades later that I learnt what a privilege it was to have butter tea made the Tibetan way. Even if it was not to my taste at the time, I think if I were offered it again today I would savour it both for its complexity and as a cultural artefact, not to forget the hospitality it conveys.

cup of butter tea with a teaspoon of salt beside it

Fast forward to January 2024, an Australian summer. People are up in arms about a scientist who suggests adding a pinch of salt to your tea might make it better.

US chemist Michelle Francl, whose book Steeped: the Chemistry of Tea is getting some publicity from the controversy, found out pretty quickly that plenty of tea drinkers (the Brits in particular) will fill comment section after comment section, social reply after social reply with “well actually…” remarks about how to make tea.

Among her crimes are the suggestions:

  • Adding a pinch of salt – the sodium ion in salt blocks the chemical mechanism that makes tea taste bitter.
  • Steeping teabags quickly but with plenty of dunking and squeezing – to reduce the sour-tasting tannins created by caffeine dissolving slowly in water.
  • Decaffeinated tea can be made by steeping a teabag for 30 seconds, removing it and discarding the liquid, then adding fresh water and rebrewing for five minutes.
  • A small squeeze of lemon juice can remove the “scum” that sometimes appears on the surface of the drink, which is formed from chemical elements in the tea and water.
  • The aroma of tea is almost as important as the taste – so when drinking from a takeaway cup, it’s best to remove the lid.

—From The Guardian

Now, let’s start by being clear that the premise of her book is the chemistry of tea. She is investigating the science behind some drinking practices and suggesting that doing X to the tea will produce Y effect. If you don’t want to produce Y effect, then don’t do X. No one is forcing you to make a cuppa for science.

On the other hand, what is the cost of trying it? Make a large pot of tea and pour a few cups’ worth. Put a pinch of salt in one, a squeeze of lemon in another and have a control version. At worst you’ve only ruined two cups of tea, right?

Of all the protestations that make me roll my eyes, the one against salt in tea “because tradition” is particularly annoying. Tibetan butter tea, developed in the Tang dynasty around 7th century ACE pre-dates tea in Europe by several centuries; noon* chai, also known as pink tea or Kashmiri chai, is derived from Himalayan traditions and also contains salt. Tea in China, before it was a beverage, was a medicine and people would add onion, herbs and salt to it to make a broth. Salt in tea pre-dates tea on its own and came well before tea with milk and/or sugar. Anyone who wants to argue about tradition is being rather Euro-centric about it.

On the other hand, a lot of tea drinkers enjoy bitterness and learn to control it through different brewing techniques. Adding salt is a good corrective for bitterness but, for most pure tea drinkers, it’s going to be a last resort.

*noon means ‘salt’ in Kashmiri

I do want to point out also that Francl’s tips are very much aimed at the layman end of the tea-drinking spectrum. I’ll respond in kind.

On tannins

Steeping teabags quickly but with plenty of dunking and squeezing – to reduce the sour-tasting tannins created by caffeine dissolving slowly in water.

So, I don’t generally drink tea made for teabags. The smaller particles (higher surface to area ratio) that are the feature of tea in regular teabags contribute to its faster steeping rate, so quick steeping is par for the course.

However, it has been general wisdom in teabag-land not to squeeze the bag because it increases the tannins, so I’d be interested to see her scientific results on this, comparing squeezed and non-squeezed teabags for tannin content. I also wonder about the sample size, and whether this is consistent across lots of brands and tea types.

I must say I don’t find that tannins taste sour either, though they do contribute to astringency, which can be the textural equivalent of sourness.

On caffeine

Decaffeinated tea can be made by steeping a teabag for 30 seconds, removing it and discarding the liquid, then adding fresh water and rebrewing for five minutes.

This method has been circulated as a decaffeination technique for a while. It has also been debunked quite comprehensively. Since caffeine testing is well-nigh impossible at home, I’d be interested to see Francl’s working on this.

Personally I’m not affected by caffeine. I’ve been known to join 2am tea sessions (this is sadly frequent as an Australian meeting with US and European tea lovers) and go straight to sleep after.

On lemon

A small squeeze of lemon juice can remove the “scum” that sometimes appears on the surface of the drink, which is formed from chemical elements in the tea and water.

I think this has more to do with the water used and the type of tea: I don’t think I ever get scum at home with filtered Sydney water and the tea I drink. Besides which, lemon affects the taste of the tea so if the scum doesn’t taste like anything, why bother flavouring your tea with lemon unless you want lemon-flavoured tea?

On aroma

The aroma of tea is almost as important as the taste – so when drinking from a takeaway cup, it’s best to remove the lid.

This is true but, uh, I cannot remember the last time I drank tea from a takeaway cup so this recommendation is irrelevant for me.

I have just bought the book – get it direct for £20 rather than from an intermediary (Booktopia wanted to charge me A$73.40 plus postage) – and I will be back with a review once I’ve rifled through.

Colour me cynical, at the end of the day this storm in a teacup is merely one of the five common kinds of content about tea that’s predictably produced for engagement. Take your hands off the keyboard, warrior, and have a cuppa instead.