Is it acceptable to microwave coffee?

Only way to know for sure is try.

Never!!

That's what I do using my rather snobby, large volume Bialetti Mokka. It doesn't seem to affect anything apart from the understanding that I'll always be at an inferior status to my coffee pot.

Tea: Yes.

Coffee: Never.

You should be banned from the forum for asking such a thing!

Tea: NEVEREVER.

Coffee: ONLY WHEN DESPERATE.

FTFY

Depends on the coffee. Old beans roasted to within an inch of their life and tasting like burnt ashes (i.e. Lavazza) - probably won't be able to tell. Fancypants third wave artisanal single origin light roast rainforest friendly organic - will be very disappointing.

Depends on the coffee

Supermarket own brand "dark roast" arabica though I am contemplating getting some expensive artisan coffee just to try...

once you've brewed and extracted using an approved method (cafetiere, YMMV if you're a single estate £1500 grinder tart 😉 ) then reheating the second cup isn't IMHO going to make a huge difference. You'll only be taking it from room temp to say 75-80C and I doubt that'll degrade the drink compared to having already been extracted by nearly boiling water.

Does the activity of microwaves create some kind of degradation of the flavour oils.....there's an analytical chemistry PhD in that.

Make sure you don't boil it and it is fine. What you mustn't do though, ever, is use your microwave to cook a haggis, forget it is on, and burn the haggis leaving a stench forever more in the microwave. That does not make for nice coffee. 

I'm struggling to see what the difference is between microwaving half a large cafetière or a whole small cafetière.

Anyway, if it tastes OK to you, do it. If not don't.

I've just begun travelling down the rabbit hole that is grinding your own beans, etc. for the first time in donkey's years. Hand grinder, Bialetti, Aeropress or filter. So I think you're an animal to mistreat your coffee this way.

I do it everyday at work. Tastes fine.

Put it in your thermos, ideally a tartan one with a glass liner and plastic cup

When I do my flat white and they are pretty good but to keep the milk silky it's never hot enough for me so it then gets 15 seconds in the microwave. This means I get the texture I want but slightly hotter .

My gripe with the £3.95 barista pour is that it often arrives lukewarm as they never heat the cup

I use the microwave to warm the milk as well. Never the coffee though. Always warm the cup first. Always.

Flask.

Why use electricity to heat it twice?

But - just the coffee. If you take milk don't put milky coffee (or tea) in a flask - thats just rank

If there’s milk involved then there’s a decent chance you’ll cook it a bit and it’ll taste a bit vomity (unless you’re careful as the posters above seem to be).

Black coffee is fine but the flavour does go a bit stale if it’s left out in the open. Best option to avoid making 2 pots or reheating is indeed a thermos or similar. That’s what I do and I’m a fancy-grinder-artisan-beans kind of guy

I use the microwave to warm the milk as well. Never the coffee though. Always warm the cup first. Always.

I zap the cup with my milk for about 30 seconds (before adding the coffee!) to take the chill off both.

The thermos is a good suggestion

Depends what the alternative is.

Nuked good coffee is better than no coffee. Unless it’s Mellow Birds, that is.

Put it in your thermos, ideally a tartan one with a glass liner and plastic cup

Just had to bin mine, it rusted through the bottom. My grandfather bought it in the 60s for his fishing trips.

I’d warm up a brew i’d forgotten about but in your case you’re just being ridiculously lazy....plus time spent making brew = time spent skiving work

should be ok if you use an artisan microwave

Hand wound in a Faraday cage by authentic Victorian children

I like coffee that tastes roughly like charcoal. Lavazza is near perfect. Although it could always be just a bit more roasted.

Couldn't care less if i have to microwave it if it has gone cold.

Makes not a blind bit of difference. I often microwave the last mug from the filter jar just don't nuke it to beyond an inch of its life. I also use oat milk. 

I often  reheat, it's fine. I quite like reheating coffee after it's been in a thermos for a day, it has a flavour that's different but a pleasant change.

It might make a difference, it might not, you might not notice even if it does, you might imagine a difference even if it doesn't, and you might think the difference is either better or worse...

Reheating is fine just don’t overdo it.

If it’s sat in its grounds for 6h in the cafetière it might not taste the best but the reheating won’t be the problem.

Also, better cooled down and reheated than kept hot all day long.

It might make a difference, it might not, you might not notice even if it does, you might imagine a difference even if it doesn’t, and you might think the difference is either better or worse…

you are David Byrne and I claim my £5

I reheat mine in the pizza oven using hickory chips beats throwing it down the sink 😕

You're reheating a brewed liquid, it's not going to change anything unless you're boiling milk.

Also, I'm surprised STW hasn't pulled you up on this yet but,

This is a cafetière:

This is a cafeteria:

Also, I’m surprised STW hasn’t pulled you up on this yet but,

<Edinburgh defence> That was a test. Glad you're the first pedant person to notice...</Edinburgh defence>

You’re reheating a brewed liquid, it’s not going to change anything unless you’re boiling milk.

Just go and warm up a black coffee in the microwave and enjoy just how shit it tastes. You’ll only do it once. Unless you’re really stubborn. Best wait ‘till the morning now though.

Just go and warm up a black coffee in the microwave and enjoy just how shit it tastes. You’ll only do it once. Unless you’re really stubborn. Best wait ‘till the morning now though.

I'll cheerfully set you up with a blind taste-test on that.

I reheated the end of the stove top coffee top brew I did on Sunday. Tasted fine to me. Not as good as fresh but better than instant by a long way.

Its going to make zero difference to the taste. Nuke away, as many times as needed.

(I’m new to this coffee snobbery).

I wouldnt be impressed if i wandered into a coffee shop and they stuck it in the microwave but leaving that aside.
Being really lazy I use a machine and if I didnt would probably go the thermos approach instead but wouldnt be opposed to trying a microwaved one.
My guess is it wouldnt make much difference but one way to find out. To really remove doubt get someone to set up a blind test of it so you dont risk making your mind up first.

But – just the coffee. If you take milk don’t put milky coffee (or tea) in a flask – thats just rank

Truth! I seldom drink coffee, unless I have a mocha in a coffee shop, otherwise I make green tea to go in a flask, or tea with milk at home. I’m basically a zero-faff hot drink person.

Are the chemicals in your coffee (acids, sugars, etc) all inert once the coffee has been brewed or do they react over time, altering the flavour? Do any reactions go faster if you warm it up?

I guess it could improve the flavour of course. Who knows? Try it, if you like it, drink it.

Properly brewed coffee will change in flavour as it cools, so I can't see how reheating after cooling won't further change it. Unless the flavours are relative to the temperature? I'm a coffee snob, not an expert, so I'd agree that the taste test and some sort of chemical analysis is required.

It's coffee for goodness sake.  A  drink that may need rewarming. Yet another trivial thing  turned into a bloody religion.

No! Make some fresh. And never use instant ‘coffee’ - 🤮

If it's for yourself, who cares. For somebody else, probably not unless they've asked you to.

Edit, agree about instant, just nope.

Yet another trivial thing turned into a bloody religion.

Burn him!!

I'm a coffee snob. I've occasionally put coffee in the microwave. It's better than lukewarm coffee. Also better than a flask, which somehow always seems to make coffee taste weird (and no, it's not just my flask).

What a great thread. Good question. I’m disappointed in the lack of scientifically orientated responses. But at the end of the day, the only really valuable test is a personal taste test.

sounds like a good question for James Hoffman!

If it’s for yourself, who cares.

... is the right answer, really. Do you want warm coffee or do you want "acceptance"? Ding it, if it tastes fine then drink it, if it tastes bad then tip it and make another.

My response was scientifically oriented, I just didn't bother to write down all the (simple) reasoning behind it, which is based on the fact that I do not believe the chemical composition of brewed coffee changes significantly as it drops from 80C (say) down to ambient and is warmed up again. It will taste different at different temps (due to sensitivity of your taste buds) but that's not changes in the coffee itself.

If the grounds are still soaking in it, that will matter, in which case it would be better to cool it rapidly after brewing and also reheat quickly just prior to drinking. Because you don't want it sitting around hot extracting more of the bitter flavours from the grounds. Extraction is much slower at colder temps.

In a similar vein, (filtered) cold brewed coffee is just fine siting in the fridge for a day or two. The extraction time isn't even very critical for this, eventually it gets bitter but that takes a while.

BTW we have just bought a rather expensive grinder and the difference from our previous (average burr grinder) is really amazing. The uniformity of the grind means that there is much less bitterness and no particles/sludge in the cup.

I’m disappointed in the lack of scientifically orientated responses.

You don't get much more scientific than try it, observe, record, report.

Are the chemicals in your coffee (acids, sugars, etc) all inert once the coffee has been brewed or do they react over time, altering the flavour? Do any reactions go faster if you warm it up?

like keeping it in a flask ?

Coffee is the new wine. Somehow it has become pretentious and has people waffling on about notes and flavours. Just microwave it, you’ll be fine.

Sure you'll be fine but the coffee will be more likely to taste like shit. Sometimes though it's okay, but more likely to be better off making a fresh one. Or if microwaving is acceptable, why isn't just drinking it cold? Just drink it cold it'll be fine. Unless it's instant and you accidentally put too much milk in, bleurgh.

Put it in your thermos, ideally a tartan one with a glass liner and plastic cup

Surely you have the STW logo-ed insulated mug to put your artisan coffee in?

Coffee is the new wine. Somehow it has become pretentious and has people waffling on about notes and flavours. Just microwave it, you’ll be fine.

Microwaving wine should speed up the process of making gløg 🙂

Properly brewed coffee will change in flavour as it cools, so I can’t see how reheating after cooling won’t further change it. Unless the flavours are relative to the temperature?

They do - temperature affects taste/flavour quite a lot. Our perception of bitterness / sweetness changes quite a lot with temperature. A friend of mine freezes Creme Eggs because the taste too sweet otherwise - but the creme egg isn't changed, back at room temperature it would taste the same. A change in taste doesn't mean anything has chemically changed in the thing that has changed temperature. Cold coffee tastes different to hot coffee - iced coffees tend to be quite heavily sweetened to counteract the bitterness, but reheating cold coffee will taste like hot coffee again, not a hot version of cold coffee.

If coffee was pure water then applying additional temperature processes which change it from solid to liquid to gas and back again would have no change, but coffee isn't just water. Neither are creme eggs, I refuse to believe. Go defrost some ice cream, and refreeze it! 🙂 IANAS

I think if you go the microwave route then you'll need to decant the second cup into a mug from the cafetiere at the same point you pour the first coffee, then microwave that mug warm, you can't leave the second mugs worth in the cafetiere half the day stewing.

Edit - am assuming black coffee, any milk to be added later post microwaving. If you do it that way I doubt there would be a massive taste difference

I suppose the temp has so much to do with things, any can of coke at room temp I couldn't drink but chilled quenches the thirst, orange juice not from concentrate unpalatable unless chilled. Could be the amount of sugar involved

Remember the 1/3rd of a pint we had to consume at 10am from March to July it was disgusting having been lying in the playground since 5am

Go defrost some ice cream, and refreeze it!

That's an unfair comparison as that's a phase change, and the taste and creaminess (mouth feel) of ice cream is affected by its crystalline structure as well as the flavour compounds. Unless it refreezes in 'the same' crystalline structure then it will be materially different even if the flavour compounds aren't changed.
We're talking about taking a liquid from about 20 to about 75, which is not a phase change and which I suspect is not high enough to degrade any of the flavour compounds, and certainly won't change the water that must be 99+% of the cup (assume here milk is not added before reheating, that would add a load more fat molecules but even then I can't see from a temperature basis alone what different effect raising milk fat molecule's temp by bringing it from 20-75 as part of the bulk, or by adding them to a hot bulk liquid at say 80 and thus reaching 75 has.
What i don't know is whether the microwaves themselves interact (and degrade) the flavour compounds, or do they just as the layman's explanation says cause the 'food molecules' to vibrate and so warm up. We know radiation can cause changes in other types of molecules (eg: UV kickstarting free radical production that kickstarts polymerisations, such as in UV cured nail varnishes) but microwaves are long wavelength and hence lower energy because E = hf compared to eg: UV as mentioned above.
You asked for science.....

That's presuming the protagonist in the ongoing microwave based coffee heating saga stops at a mere 75C! 85C would probably be okay too... but I bet these heathens nuke it from orbit, to be sure 😉

If only STW had a poll feature for users. I'd love to be able to make a Venn diagram showing the intersections between those who use the microwave to reheat their cold hot drinks, those who ride e-bikes, insist on British made woolly jumpers and extra tall cars to put their bicycles in 😉

Insulated cafetière serves me well for my two cups spread out over the morning:

La Cafetière Stainless Steel Double Walled Insulated Cafetière 8 Cup, Stainless Steel, Silver https://amzn.eu/d/j4IORTG

Chemical reactions are generally much slower at colder temps but there aren’t really any chemical reactions going on in coffee other than a slow process of oxidation of some things.

Volatile flavour compounds will tend to evaporate off if the coffee is kept hot for a long time. That’s not a chemical reaction though.

Woah, hold on. All this talk of reheating or not and no mention of:

I limit myself to two mugs of coffee per day

what kind of madness is this?  Two per hour maybe. If I was forced to limit myself to just 2 mugs I’d rather just drink water.

FB-ATB earlier:

The great Hanes Joffman thinks something.

Edit: the full original video is quite interesting.

Obviously you need a £180 smart mug

The smart mug is one of the options tested in that James Hoffman video and comes out top, ahead of both a thermos and microwaving.

but he did find that of the reheating methods he used, the best was microwave in small increments to reach drinking temp (don't whack it and then let it cool again)

Obviously you need a £180 smart mug

he’s not a £180 smart mug, he’s a £700m absolute ****.

A scientist barista once told me that microwaving coffee will shrink your balls. I hear it’s better to batch brew it and leave it in a thermos.

I do it all the time, I make a big mokka pot one day and if there's enough left the next day I'll just microwave it, what a scuzzer eh.

It's never as nice the next day obvs, coffee really needs to be drunk when freshly brewed as it loses it's mojo after a while, certainly after 24 hours anyroad.

It’s never as nice the next day obvs

Stick the coffee in the fridge (after adding milk) and have it cold later (or next day). Different but still great tasting (assuming it was decent tasting when made).

Microwaving it (even when black) makes it taste like shit to me, in my experience, every single time. Tastes are always different though. If you like (or don’t care) what coffee warmed up in the microwave tastes like, crack on.