Heating the Mug – The science of achieving the right temperature in mug-brewed tea

Tea-making behaviour has changed in the West, from loose leaf tea brewed in pre-heated pots, to “tea” bags brewed in mugs.  But in this movement to convenience, has the flavour been lost in methodology?

From adverts for brand tea bags to instructive videos on YouTube, self-styled exemplars fail to recognize the essential loss of consistency in the transition between the pre-heated pot to the mug.

Brewing tea is not nothing more than the addition of once boiling water to a location near the tea.  Mass marketing suggesting this method might be adequate contributes to an experience of modern life that is rubbish, meaningless and unsatisfactory – with an £84bn transnational encouraging human beings to irrationally follow a half-wit knitted monkey ted.   “Knat’s piss”, I hear my long-gone grandma call from her dining room table in 1985, deriding the product of a near miss between tea and nearly hot water in her broad Lancashire accent. Do not follow the monkey, though because others do, Unilever’s shares have risen about 4-fold over 15 years.

You must plan to enjoy your tea, and plan to spend the time and effort on making and savouring a good cuppa is a revolutionary act!

Making tea in a china mug is also a scientific endeavour. If you spend 40 minutes drinking tea each day, not uncommon here in the UK – you may spend 3 years of your life engaged in this pursuit. If your method of brewing the cuppa is lacking, this might mean you end up sipping an unsatisfactory beverage for 1000 days of your existence. It might seem like a sentence: but it need not be, and this brief article might just be your get out of jail free card.

Lamenting the lack of flavour in the cups of tea I was drinking at home, compared to at some cafés, I did an experiment with my digital catering thermometer.  A tenner ensures the 3 years of my life spent drinking tea will be more than satisfactory, but a pleasure.

According to Lifehacker, black tea should be steeped at 90.5 – 96ºC. Though the water in your electric kettle may be close to 100ºC at peak, it cools rapidly, and the temperature drops of significantly when poured into a much cooler receptacle like a cup or a mug. The colder and heavier the mug, the larger the thermal mass which will suck the energy from your boiling water, potentially leaving your tea brewing water tepid.  But just how much does the water cool, and will it affect the quality of your cuppa?

The first part of my experiment simulated what happens when I made a cup of tea by simply pouring freshly boiled water onto a tea bag in a cupboard cooled mug, but without the bag: the water was rapidly cooled by the colder mug to 83.5ºC, and fell quickly. However, after allowing the mug to equilibrate with the “boiling” water for 30 seconds, then discarding the hot water, and replacing with another mug full of freshly boiled water – I achieved a temperature of 93ºC. Within 60 seconds, and certainly at 120 seconds, this produces a much more satisfactory cup of tea than tea made in a cupboard-cold mug.  Try it for yourself.

Therefore the remedy for a post-“heated-pot teapot” world is “heating the cup”.  Let this be your manifesto for the moment. Dispense with revolting half-brew. And tea-up for the revolution!

NB. If you are a heretic, and you add the milk to your mug first, an acceptable variation is to microwave the tea bag in the milk for 20 seconds prior to adding the boiling water.  This is a rapid route to “builders” tea, which in addition facilitates the extraction of certain fat soluble flavour compounds from the tea.


About jonnyr9

I'm an enthusiastic amateur "scientific" cook and baker, and former scientist, and I like to bring scientific thinking to my cooking: thinking about what might be happening at a chemical or biological level during food preparation (including its growth, and preservation), and applying exact methods of mass and volume to core recipes, before varying them. I use an accurate weighing scale (to 0.1g). I like growing my own herbs, constructing my own raised beds, and constructing my own wood-fired pizza oven. I bring a certain level of OCD to the kitchen, and therefore my baking includes sourdough, and my pizza-making includes "reference" to the protected specifications for true pizza. If I can source "the right" ingredients for a dish, I will at almost any length (within reason) - before I find an equivalent in-country supplier. Therefore - if you've never eaten Lancashire cheese bought at Bury market near Manchester - you've never eaten Lancashire cheese. I'm going to try to include links to the same products I use in my blog, so my readers don't end up using sub-standard alternatives - "experimental replication" is key to scientific cooking. I was born in the North of England, but I live in the South, though I would prefer to live on an island in the Ionian Sea.
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One Response to Heating the Mug – The science of achieving the right temperature in mug-brewed tea

  1. limanatf says:

    It is important to think about the temperature when cooking tea, especially that it differs from a tea variety to another.
    Thanks for sharing your experiment.



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