(soft music)
- Welcome to another episode of understanding espresso,
and today we're going to be talking about
a kind of interesting topic that is occasionally contentious
and that's brew temperature.
Now to begin with what I want to do is give you
just kind of a brief history,
a brief overview of how we've thought about
and talked about brew temperature for espresso in the past.
For many people that goes back to the old online groups
of alt.coffee where people got together
and began to talk about the frustrations they had
with their domestic espresso machines
and the way that they sort of set the temperature
for brewing.
They found that to be inconsistent and frustrating
and so began to put PIDs on them.
Now, a PID is a certain type of controller
that can be applied for a bunch of different stuff,
but here it was a way to manage and maintain temperature
to improve the consistency of their espresso.
This spread from places like alt.coffee
into the commercial world.
And one of the people that was driving the conversation
about brew temperature very early on was David Schomer.
His book was formative for many people, including me,
and it really drove a lot of the conversation
in the early days of what is now kind of modern espresso.
He believed absolutely in the idea
of flat line temperature brewing,
that a machine should deliver a constant temperature
of water from the beginning of the shot
to the end of the shot.
And he said this unlocked levels of sweetness
in his espresso.
He really believed that it made it taste
much, much, much better, and maybe it did.
A lot about this is down to personal preference
and we'll touch on that later on,
but he certainly drove the conversation.
For machine manufacturers this was kind of great.
The problem of having a machine just deliver
the same temperature of water from the beginning of the shot
to the end, that's not a complex engineering challenge,
and a number of manufacturers rose to the occasion
and came up with great solutions to do that thing.
The whole flat line brewing thing was really
just a neat easy to communicate idea.
It's something you could test at home.
Did my machine deliver water at 93 Celsius
from beginning to end?
And what got lost a little bit at the time
was the idea of temperature profiling,
a natural curve to temperatures because what I think
is much more important than having a flatline profile
is having the same profile time and time again.
And by having a flat profile, that meant that chances are
it was flat every single time you used the machine
and that was good, but it doesn't necessarily mean
that having some variances is a bad thing
as long as that variance is the same every single time.
That conversation is still a little bit muddy out there
because there aren't many machines
that do temperature profiling on purpose.
Some of them will have a natural curve,
but I don't think there's a ton of evidence around
on one curve being better than another.
An overall brew temperature,
I don't think it quite unlocks perfection
the way that we kind of hoped it would back in the day.
We did hope that if we achieved
this perfectly flat temperature profile
that we would have this of a leveling up of espresso
and that didn't happen,
but we got more consistent equipment and that was good.
So today, when we talk about temperatures,
we'll talk about either I guess a flatline profile
or your peak temperature or sort of the temperature
that your curve we'll spend the most time at.
If your machine does produce a range of temperatures,
don't freak out as long as it does the same thing
every time basically.
Now one thing we have to touch on again
is the idea that's now called temperature surfing.
This is how you use your machine
to get it to act in a more consistent manner.
There are generally two different outcomes
of temperature surfing through the same kind of process.
By pulling water out of the group head
before you pull a shot, you'll do one of two things.
In some machines you'll pull out some very hot water
that's too hot to use and that will cool the system down.
And if you time it right, you can catch it as it comes up
to a kind of ideal temperature.
In other machines, you'll actually heat up the group head
with the water flowing through it
and then have again your desirable temperature afterwards.
There's tons of resource online for particular machines
about temperature profiling routines.
I would check out some of the forums like Home Barista,
Coffee Geek, and I'll leave some links to those down below.
I can't tell you the perfect temperature surfing routine
for your machine, because there is simply too many machines,
but someone probably has worked it out
and they are sharing it in those kind of communities.
So let's talk about temperature and taste,
because that's the thing we're really interested in, right?
Like how does my temperature impact the taste of my espresso
and therefore how should I use temperature
to improve the flavor of my espresso?
Now temperature works in kind of a simple way
in that the hotter you go,
the more you are going to extract.
What I would say is that it's very difficult
to make a decision about changing temperature
based on only one or two espressos.
Temperature, unless it's miles away from being correct,
is a kind of tweak, a small adjustment.
It'll help you clean up something
that you don't like about the espresso.
For example, if you have this consistent,
slight kind of unpleasant acidity
no matter what you've done to change your ratio
or your recipe or your dose,
then that could be an opportunity
to increase your temperature to increase your extraction
to kind of clean that up.
But if I just tasted one shot and it was a little bit sour,
I'd look to something like ratio first
before just jumping straight to temperature.
But if it's there time and time and time again,
then that tells me that this coffee
might need a little bit more heat.
Similarly if no matter what I do there's a little harshness,
a little bitterness to the espresso,
then I would potentially drop the temperature
down a little bit.
It is a different kind of harshness
to say dirt in a machine, which leaves a very lingering,
burned kind of bitter flavor here.
Generally overtemperature espresso just is quite bitter
up front and a little bit harsh and aggressive that way.
It's kind of rough edged to me.
It lacks a kind of clarity and sort of smoothness to it.
And I know we're getting to slightly pretentious language,
but you know it when you taste it.
Now generally, most of the time we're brewing
in a couple of different ranges.
I would say you're going to brew between 85
and 90 degrees Celsius for darker, more developed roasts.
Between say 88 up to say 92
for kind of medium espresso style roasts.
And I would brew anywhere from 90 all the way up to 95
for lighter espresso roasts.
Now those are pretty ballpark numbers,
but I also believe that typically
within that sort of window, things should taste pretty good.
I know that some people had experiences
where they've adjusted the temperature
by half a degree Celsius and had a good shot the next shot,
but they might've solved a different problem
in that second espresso.
They might've pushed through a little bit more liquid.
They may have had a slightly different mix of coffee beans.
It's an organic thing, it's grown on a farm.
It's not identical.
There's a number of different reasons
one espresso will be different from the next one.
So you have to be careful ascribing an improvement
to one particular change and that's true of all espresso.
Generally I would make a change
of at least one degree Celsius
in order to expect a noticeable change in flavor.
So if I was pulling shots at 92
and I was just wanting to improve things,
I would most likely go to 94 other than 93,
but 93 would be the smallest single change.
That one degree Celsius change
or around two degrees Fahrenheit.
Now many machines will let you change it by less,
but I honestly don't think
that's a significant enough change to fix the problem
that may have come from temperature.
And again, with darker roasts,
these lower temperatures will prevent you extracting
too much in the way of bitterness, in the way of harshness.
Whether it's filtered coffee or espresso,
there's a correlation.
The hotter your water, the more you're going to extract.
And that can be a good thing sometimes with lighter roasts
or that can be an unpleasant and unbalancing thing
with darker roasts.
Now, there are a couple of weird outliers.
There are some interesting ideas around profiling
that I want to talk about
and we do need to discuss temperature and altitude,
but I've got a couple of things to talk about first.
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So up until this point,
it seemed pretty arbitrary, pretty simple.
Use your temperature to extract more or less.
If you've got a dark roast,
extract a little bit less to have more balanced shot,
but can it really just be that simple?
And for the most part, I actually think it is.
Brew temperature is not something
I mess around with on the daily.
I'll typically start with a recommendation
from a roaster and see how they're brewing their espresso
and that'll be my benchmark.
But beyond that,
I rarely really change brew temperature
to improve the taste of my espresso.
I'm using things like ratio or using my initial dose.
They just have a bigger impact,
but here's a few little things that I think
are kind of interesting that are worth sharing.
Now firstly, this requires some level
of temperature profiling,
but it kind of blew my mind when I learned about this.
I was once making espresso with a very,
very dark roast of coffee,
darker than I really wanted to drink
and I was struggling to get the best out of it.
Now this was using machines that had a brew boiler
and a group head that you could control it
as your temperature independently.
And in doing this, you could create a temperature profile,
and here with very dark roasted espresso
I had very good results
starting with a kind of hotter initial brew
and cooling it down in the sort of second, third,
and final stage of the espresso.
On the T3 unit I was using
on a Black Eagle espresso machine,
I had the brew boiler running at 105 degrees Celsius.
It's pressurized so it can still be liquid
at that temperature,
but my group head was running down at 80 degrees Celsius.
Now the initial liquid that goes from the brew boiler
to the group head flows quite quickly
and so didn't lose too much temperature.
It meant the start of my espresso was actually pretty hot,
but by the time that the flow had slowed,
that hot water was spending more time in contact
with a big thermal mass of cooler metal.
That meant that we have this cooler profile
in the second two thirds.
This meant that my extraction at the start
was actually pretty good,
but by reducing the temperature in the second half,
or second to two thirds, it seemed to reduce the bitterness.
So you ended up with an interesting textured
complex espresso for a very dark roast
without this overwhelming bitterness.
By having the whole profile set at a lower temperature,
it wasn't bad, it just got a bit boring.
And this hotter start just made for a more interesting,
delicious espresso.
Running a brew boiler at 105 degrees Celsius,
it seemed totally at odds with everything I knew
about brewing dark roast for espresso,
but the results were super interesting.
If you want to try it,
if you have a machine that can produce
some sort of temperature profiles.
Talking about brewing at lower temperatures,
I will say pulling shots at 80 degrees Celsius
is kind of a head wrecker.
Think of it in a way as the cold brew of espresso brewing.
Now you're not cold brewing,
but you have a similar kind of thing.
You end up with this very pleasant textured,
very kind of low acidity round, desperately dull espresso.
But it broke my head,
the idea that once I dropped below a certain temperature,
I just couldn't really extract a bunch of the acids
that were quite unpleasant
if you've got a little bit of them.
If you brewed that same coffee at 85 to 90,
it would be overwhelmingly sour,
but that actually dropped away at 80 degrees Celsius.
It's not the most interesting espresso of your life,
but if you have a machine that can do it,
it's definitely an interesting little experience.
Don't expect the same level of creamer,
don't expect the same intensity,
but the texture is generally very enjoyable.
Now one last one to talk about is altitude
and espresso brewing temperatures.
A lot of people know that the higher up you go
in terms of altitude,
the lower the temperature that water boils at.
And if you're brewing at 93 degrees Celsius in a place
where water boils at 93 degrees Celsius,
is that a massive issue?
And the answer actually is no,
because when you're brewing espresso,
that environment is actually sealed and pressurized.
When you're brewing at nine bars,
water cannot boil at that temperature at 93 degrees Celsius.
It's too pressurized to do so.
It's only at very low pressures that it can boil
below a hundred degrees Celsius.
So when you're brewing your espresso, there are no issues.
You can keep brewing at 93, 94, 95, 96,
even though your water may boil at cooler temperatures.
One thing that will happen though is that
as your your espresso liquid leaves the basket
and leaves this pressurized environment,
that lower pressure tends to cause much bigger,
foamier looking creamer.
And if you're pulling shots without scales,
it's really hard to assess how much liquid you've got
cause you just have this much fluffier espresso.
So all I would say is that pulling shots by eye
and at high altitude is incredibly difficult.
Expect your creamer to to sort of be less stable
because these bubbles are bigger and less stable,
but if you hit your ratios
it should taste completely delicious.
A lot of people worked this out
when the World Barista Championships were in Bogata
and everyone was brewing on scales
because their shots just looked too weird
because of the altitude.
That was really interesting.
But now I'll hand it over to you.
I'd love to hear your thoughts on brew temperature.
Do you mess with it a lot?
Do you find that small tweaks actually yield big results
in contrast to what I experienced?
I would love to hear from you 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.