Here's the question.
Is there a better way to reheat coffee?
I get this question a lot, a lot, a lot.
People wanna know, "I've let my coffee go cold.
What should I do? Should I microwave it?
Should I put it on the stove?"
What's the answer here? I have no idea.
I've historically just given them the kind of party line
of don't reheat your coffee.
It makes it taste bad.
And I know that is true.
I know that if you get a jug of coffee
and you leave it on a hot plate for half an hour,
it tastes much, much, much worse.
But I honestly don't know if there's a way
of reheating coffee that tastes better.
So here is what we're going to do.
I'm gonna brew a big batch of coffee.
I'm gonna split it into five different samples.
Two of them, we're gonna try and maintain the temperature
throughout using ways.
Three of them, we're gonna let them go cold,
and then we're gonna reheat them.
And at the end of all of that,
I'll do a blind tasting
and see if one of them tastes better than the others.
First things first, I need about a liter of coffee.
I'm gonna have to brew a bit more than a liter of coffee
because I need a liter of finished coffee.
And I'll lose some to the grounds,
so I'm gonna brew about 1.2 liters.
I don't have a brewer that does that,
so I'm gonna have to brew twice,
and I'll blend them together
so that we have one consistent beginning brew
for our testing.
Let me get on with that.
And, hey, I get it. I am forgetful.
I leave my coffee lying around all the time.
Cold, cold coffee when you want a hot coffee,
it's a wildly disappointing thing,
so I get the urge to reheat it.
I generally don't, but I always have coffee available.
And should I really be telling people just to throw it away
and make it again?
I'm kind of hoping for an interesting result here,
but who knows?
Now, as I said, I don't have a big brewer,
so I'm gonna have to brew two batches,
which means this goes in here, and I brew as fast as I can.
I know it's not ideal to brew twice and have it sit around,
or half of it sit around,
but it shouldn't invalidate the testing.
Let's brew again. All right, second brew.
Took me about five minutes to turn it around,
a little bit less.
So that's good.
Now, here I've got five bowls.
They've each got a number on the bottom
to correspond to the way we're gonna heat them
or reheat them or whatever we're gonna do,
but that way I can't see what they are later on
in the blind tasting.
I'm gonna take three of those bowls
and fill them with 200 grams of liquid
and put them aside to go cold.
Now, for the other two, we're not gonna use the bowls yet
because this coffee's gonna go into two little vessels.
First up is the Ember Mug.
If you don't know the Ember Mug,
I'll stick a link to a video up here.
You can learn a bit more about it.
It is expensive.
It is a smart mug that requires firmware updates.
It is able to keep your coffee at a perfect temperature
for minutes on end.
It is completely ridiculous.
And worst of all, I love it. It's great.
It's really nice to have a cup of coffee just held
at the right kind of temperature
so that when you go away and get distracted and come back,
oh, it's just a moment of delight
to find your coffee perfectly drinkable.
I hate myself for how much I like this, but it is great.
Now, I've set this a little bit hotter than I would usually
because I want to be able to sort of transfer it
into the bowl to a kind of nice drinking temperature.
So I'm gonna hold it at around 60 degrees Celsius.
My preferred drinking temperature is more like 54,
should you wanna know those things.
It's now powered up and ready to go,
so I'll put 200 grams in.
And this should hold its temperature
for the next 30 minutes.
And then we've got this thing.
This is a classic little Thermos.
I've had this one a long time.
It's pretty dinged up, but it's an old technology.
It's been around a good long while, but we know it works.
And so now we wait for 30 minutes.
Then we do some reheating, and then we do some tasting.
What I'll do now is just have a quick taste
of the last little bit left over,
just to see what it was like fresh.
I won't have this as a benchmark later on,
but interesting nonetheless.
Mm.
So now that we've waited 30 minutes
and these are all below body temperature now,
they're all pretty cool,
this room's quite cool, actually, now that it's winter,
I need to work quite quickly
to reheat each of these three in a different way.
I'm gonna use two pretty classic methods
and one kind of wildcard in all this.
So first up, for this one here,
we're gonna reheat this with a stove.
We're gonna put it in a pan, heat it back up,
probably around 70, 75.
Obviously we're not gonna bring this to a boil.
That would definitely be bad.
But I feel like 75, 80, that's hot.
It's too hot to drink again, but a kind of realistic way
that many people probably reheat their coffee.
Done.
It's the trusty microwave.
Now, a lot of people have weird anti-microwave issues.
There's all sorts of like it ruins the nutrients
in your food nonsense.
If you are on that bandwagon,
I'm open to a peer-reviewed study,
but for now we're just gonna use this to reheat our coffee.
Let's just give you, I don't know, 30 seconds.
Perfect.
Hot, hot, hot, hot, hot.
Onwards.
This last one's kind of a wildcard.
I'm gonna use a steam wand to steam it hot again.
Now, that is gonna cause one small issue,
which is it's gonna dilute this a little bit more.
When you steam milk,
you'll generally add about 10% weight to the milk
by steaming it from just the condensed steam.
See what happens.
This might be a problem for the blind tasting.
It's a little bit foamy, but those bubbles should disappear.
Maybe we'll skim 'em off,
but now we've got obviously more coffee
than we started with, so...
Not too much more, actually.
That's kind of interesting.
And then back to the beginning.
We have our Ember Mug,
which has held it at around 57, 60 degrees Celsius.
Gonna decant this in as neatly as I can.
Got our friendly Thermos.
And our three other bowls,
one of which will need a little bit of preparation,
just to make it look normal.
I'll skim that with some cupping spoon.
Hopefully the last few just dissipate away.
So time for our blind tasting.
I'm gonna go away.
Michael's gonna come in and switch the bowls around
so I don't know what's what.
They should be similar temperatures, I presume.
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It is tasting time.
I don't know what I've got here, but I'm curious.
Now, the theory would be that the hotter you hold coffee,
the more it's gonna degrade.
The hotter you make coffee, the more it's gonna degrade.
That's why if you hold coffee in a glass pot on a heater
at 90 degrees Celsius, you cook it, and it tastes terrible.
Can the Ember get away with holding it
at a lower temperature?
Does the Thermos work
because it's not pulling heat out the same way,
rather than there's no additional heat being kinda put in?
I don't know, let's see if there's any difference in taste
between all of these.
Okay, I'm gonna immediately rule one out
'cause it just tastes weird.
It's got this introduction of this whole other kind
of weird taste that kind of reminds me of papery caramel.
And I know that doesn't sound entirely awful,
but it's definitely weird and wrong.
It's got this artificial sweetness
that's just very confusing.
That's just really weird. That's really weird.
I'm just gonna say you're out for now.
You're not the best one here.
This is difficult.
We're into nuance here.
I really thought the differences would be more pronounced.
I think I'm gonna kick this one out
for being a bit more harsh and kind of bitter.
I'm also, just on kind of bitterness alone,
I think you're out.
I'm so nervous about what I'm picking.
What if I endorse heating it on a pot on a stove?
Okay, I'm also gonna, I'm gonna kick that one, I think.
This is very stressful.
What if this is something ridiculous?
Oh, interesting, the winner was number one,
which I think was the Ember Mug.
So that's spent the least time being hot.
It was held at 60 degrees Celsius.
It was never heated above that.
Sort of cooled to that temperature and sat there.
And it just had a little bit less bitterness
and a little bit less harshness than the other cups here.
This one here, number five.
Oh.
Wait, number five was the steam wand.
This is a little bit embarrassing.
At the end of the edit of this video,
we realized that I had made a massive mistake.
I'd managed to switch around the labels
underneath the bowls for the three reheated brews.
Thankfully, we captured the mixing up of the bowls on video
and were able to work out what was what.
I'll just give you a quick summary now
of the truth of all of this thing
because if you listen to me talk about which one is which,
I get it all wrong.
And I'm pretty confused, but I get it all wrong.
What on Earth were you?
Number three.
Let me tell you the ranking of the reheating.
Last place, steaming it.
It had this really funny taste.
I described it as kind of a papery caramel.
It just tasted a bit odd.
It might've been the residual water from the steam boiler.
I don't know, but it just wasn't good-tasting.
Second place of the reheating methods was the hob.
I described it as being a little bit more bitter
than the others, and that wasn't good either.
In fact, the best of the reheating turned out
to be the microwave.
I'll speculate now that it was done that way
because I pulsed it
in two or three sort of small heating sessions
up to just the right temperature.
It never got overheated, and it was a gentle heating method.
So of the reheating methods, in my experience, in truth,
the microwave did a little bit better than the others.
The ultimate conclusion of the video is still correct,
and so for that I'll hand you back to past me to explain.
This was not an exhaustive scientific test,
but it was pretty interesting,
and the differences are not as big as I expected,
but they are definitely there.
The Thermos isn't a bad choice,
but ultimately holding coffee at a cooler temperature,
at a drinking temperature seems
to preserve its taste better.
Now, unfortunately, this does continue the narrative
of my coffee went cold, how should I heat it back up,
the answer mostly being don't.
But mostly, if you can, don't let it go cold.
Drink it warm. Keep it warm.
A Thermos is a good way to go.
Something that holds it a little bit cooler
is maybe a way to go.
Now, one of my issues with Thermoses is
that they do keep the coffee almost too hot to drink.
I get annoyed if I'm half an hour from home
and I still can't drink my coffee,
so I often brew onto an ice cube or two.
That might be scandalous, I don't know, but it works for me.
It's easy, it brings it down to a nice drinking temperature,
and it holds it there.
So again, might be a good way to go for you.
There are more and more Thermos-style cups available
on the market.
I think about the one from Fellow off the top of my head
that springs to mind, but there are others available too.
But interestingly, the Ember performed really well.
An interesting test.
I would say hold your coffee at drinking temperature
and no hotter.
That's the learning from today, I think.
But I'd love to hear from you.
Did you replicate this? Could you replicate this?
I'd love to hear if you've found another way
of reheating coffee that works better than all of these.
Let us know down in the comments below.
But for now, I'll say thank you so much for watching,
and I hope you have a great day.