If your cup of tea goes cold, do you put it in the microwave to warm it up again?
It’s a practice that divides the nation – while some really don’t mind it, for others there’s nothing worse.
Some studies suggest that reheating tea in the microwave could help save the environment.
But others claim it affects the taste and creates uneven heat distribution throughout.
To help settle the debate once and for all, we asked Mark Miodownik, University College London‘s Professor of Materials and Society.
And according to the expert, the ‘only thing worse’ than microwaved tea is a cuppa that’s served on an airplane.
‘The main reason not to reheat it is that it won’t taste very good,’ he said, speaking to MailOnline.
‘Microwaved tea is terrible. It’s just terrible.’
For some, microwaving tea might seem a quick and easy way to heat it up again. But Professor Mark Miodownik says it’s a ‘terrible’ idea (stock image)
A previous study showed that when water is boiled in a kettle, it is heated from underneath, causing the water at the bottom of the kettle to become less dense and move upwards by convection (left). In turn, colder water can then sink down to be in contact with the heat source — until, eventually, all the water in the kettle is heated uniformly. In a microwave, however, the electromagnetic field used to heat things is pervasive, but not uniform — causing ‘hot spots’ of heating in the liquid, as well as a warmer top than bottom
Scientists have spent decades debating the best way to make a cup of tea. This method is what William Gorman, chairman of the Tea and Infusions Association, has previously suggested
Professor Miodownik explained that flavonoids – naturally-occurring compounds which are abundant in tea – are what give the drink its distinct flavour when brewed.
But these are extremely volatile, meaning they evaporate easily.
‘They just disappear, so if you don’t drink your tea soon after you’ve made it then you don’t get very many of them left,’ he said.
‘And if you reheat your tea, you get zero.
‘They don’t stay around for very long and if you heat it up again they go away faster.
‘Coffee is a more forgiving drink, but tea has a much more delicate flavour range.’
While coffee can ‘withstand a lot’, it also contains plenty of flavonoids.
Therefore, someone who really loves the taste of coffee – an aficionado – should avoid reheating their cup, because it will also lose some of the taste.
One US scientist recently caused controversy by claiming that the perfect cup of tea is made with hot milk and a pinch of salt
Professor Quan Vuong of the University of Newcastle has previously told MailOnline that two minutes in the microwave unlocks the same amount of healthy chemicals as brewing for 20 minutes
According to Professor Miodownik, the worst cup of tea you can get is on a plane.
There, a combination of factors including low air pressure and dry cabin air can lead to a reduced sensitivity to taste and smell at altitude.
‘When you’re asked if you want tea or coffee on an airplane, never say tea,’ he advised.
He also said the office tea round can be fraught with issues – and that people are better off making their own drink.
‘Never get someone else to make you a cup of tea – this is a recipe for hating your colleagues,’ he said.
‘It’s much better to go into the kitchen with them and make it alongside them. Otherwise, they’ll do it badly or not how you like it, and you’ll hate them.’
Another factor to consider is that water – the main component of tea – can also vary, he said.
Certain areas such as London, Kent and Cambridgeshire are renowned for having hard water, which can affect the taste.
‘It’s a very sophisticated drink with loads of variables,’ he concluded. ‘Do not underestimate what you’re dealing with here. It’s the best drink in the world for a reason.’
The study comes shortly after the British Standards Institution’s (BSI) official guidelines revealed that milk should be put in the cup first – at least when a pot is being brewed
Professor Chris Budd, from the Department of Mathematical Sciences at the University of Bath, also weighed in on the debate.
He told MailOnline: ‘It’s perfectly fine to heat your tea in a microwave, as water is a good conductor of microwaves, and the convection currents in the tea ensure even heat distribution without hot spots.
‘However, be cautious with ceramic cups—they’re excellent microwave conductors and can get extremely hot.
‘In contrast, when cooking food in a microwave, hot and cold spots can occur due to standing wave patterns and poor heat conduction, which is why it’s important to stir food after heating.’
Professor Quan Vuong, head of food science and human nutrition at the University of Newcastle, previously said that the recipe for the ‘perfect’ cup of tea will depend on your goals.
‘In terms of enjoyment, a perfect cup of tea is characterized by an attractive colour, balanced flavour, pleasing and inviting aroma, as well as a pleasant taste and aftertaste,’ Professor Vuong told MailOnline.
But, there is more to the humble cuppa than its taste.
Professor Vuong added: ‘In relation to health benefits, a good cup of tea is associated with high levels of phytochemicals such as polyphenols and theanine.’
And, if it is the healthiest cup of tea you are after, then Professor Vuong has a very unusual recommendation – brew it in the microwave for two to three minutes.
He says: ‘Microwaving is a technique for preparing a cup of tea with high levels of phytochemicals beneficial for health.
‘The microwave is employed to effectively extract phytochemicals from tea due to its rapid and uniform heating, leading to the quick extraction of phytochemicals from tea leaves into the water.’
Just a few minutes of heating in the microwave extracts the same amount of phytochemicals as brewing tea in 80°C (176°F) water for 20 minutes, he claims, although he does admit that ‘this tea may lack enjoyment in terms of taste and flavour’.
But, if you’re not impressed by the prospects of tea lacking taste and flavour, Professor Vuong does have some more practical advice.
He says: ‘In my opinion we should prepare the tea before adding the milk. The protein in milk can bind with polyphenols, minimising their rapid extraction into the water.’
However the final say may lie with the real tea experts.
A spokeswoman for Yorkshire Tea said: ‘We all know the frustration of putting your mug down and coming back to a cold brew.
‘At Yorkshire Tea, we recommend that you put the kettle on again and make a fresh one.
‘That is not always practical and some people use the microwave to reheat their tea. But it can make it taste a bit funny, especially if you have added milk and sugar.’
