- Warning, this video gets very, very nerdy.
(upbeat music)
Today we're gonna dive into the science
of how a moka pot works.
And to be honest I thought this was gonna be easy.
I thought this was gonna be fun.
I thought that this little ubiquitous Italian brewer
that everyone uses, everyone can use,
it's gotta be simple, right?
Wrong, really wrong.
This thing broke me intellectually, emotionally.
It just destroyed me.
And I wanna tell you the journey that I've been through
trying to understand the moka pot.
So you might've seen that we've done an understanding
before, we did an understanding of the AeroPress.
This one is gonna be a little bit different
because with the AeroPress I could brew
as part of the whole video,
and it was kind of easy and quick.
Here, not so much.
One brew can take quite a long time.
And so going through all the brews just isn't practical.
So for the last week we've been doing a ton of research.
I'm gonna talk you through the tools that we've had
to do that research.
Firstly, let me show you the Franken-moka.
So this is a Franken-moka setup ready to go as it would be.
And you can see there's a sort of
mess of cables coming off it.
There's tubes, there's these weird gauges,
there's quite a lot going on.
So this rig, these two pots actually, were both built
by Gabor from SEP.
Very grateful to him for all the work he did.
He did an amazing job.
There's actually a video of him building these pots,
I linked to that down below if you wanna watch it too.
Now as for how the pots actually work
there's three temperature probes,
and one pressure sensor on the pot.
Two probes are here,
and they're actually running into the base of the unit,
into the water reservoir of the base.
One of them sits under water,
and we'll give you kind of your water temperature reading.
The other one kind of goes up through the funnel
to just below where the coffee sits,
and this should give us a kind of brew temperature in a way.
The other probe sits here on the side,
and that's monitoring the temperature of the upper chamber.
We'll talk about why that's important later.
Off the side here you can also see a little tube
running to a pressure gauge,
so we have a sort of manual reading of what's going on.
And then this transducer that then connects to my telephone,
so I can have a live pressure reading
to .01 of a bar second-by-second
as the whole brew happens.
Now he did one more mod which is this thing here,
this little tube.
What that's doing
is essentially taking the coffee as it brews
away from the pot so we can collect it somewhere else.
This means that with the SEP app
we can look at the flow of liquid through the bed of coffee.
We get a kind of flow rates to track.
So we get a lot of data points.
Beyond that we're tracking the amount of coffee
that we put in,
the amount of liquid in total that we get out.
We're doing extraction measurements here
with a VST refractometer.
So for every brew before we've even tasted it
we've collected a huge amount of data.
Now I'm super grateful that Gabor did two pots
because this one is set up very slightly differently.
And this is important for the first test
that we'll be doing.
I took off the flow tube here,
and instead put another temperature probe in down that thing
to try and get just above where the coffee is leaving
the sort of filter basket part of it,
and flowing up that tube
to kind of get a temperature of brewed coffee from that.
That was interesting.
A little bit tricky,
but it was another useful data point.
I have to say having had two pots has been amazing
because they're a little bit finicky to work with
I'm not gonna lie,
and being able to reset one while another is brewing
was super, super helpful.
I was able to brew with these pots
in a way that I wouldn't be able to without all of the data.
You can do really cool interesting things
that you can't do
without temperature and pressure sensors on there,
so if you want one of these you're in luck.
At Gabor's request we're gonna raffle these off.
There's a link down below.
We're gonna raise money for World Coffee Research.
If you're not familiar
they're a nonprofit focusing
on the long-term survival of specialty coffee
on the producer side.
So they're, they're not focused on roasting coffee
they're just on growing coffee.
For you if you donate $3 or more you enter a raffle
to win one of these things.
I'll ship it anywhere in the world that I can.
Link down below.
So thank you to Gabor for his work, his donations.
And if you want one of these,
and I tell you, you kinda do if you like moka pots,
then the link's in the description.
Let's get on to some actual testing.
So the way today's gonna work is I'm gonna go through
sort of experiment by experiment
to give you the data and the results from what we tested.
And the first thing that we tested
was starting temperature in the base of the moka pot.
If you put cold water in or freshly boiled water in
what's the difference?
So we ran five simple tests.
We started with the base at 20°C, 40°C, 60°C, 80°C,
and freshly boiled water.
Relatively easy to do,
but we did have a small quirk.
Because we were trying to be really consistent
I was weighing the water
before putting it into the base of the pot,
so we always used 200 grams of water every single time
to retain some consistency.
This meant that the 80°C water
would lose some temperature there,
and lose it again going into a cold pot.
So even though we heated the water to 80°C
before loading it in for example,
it wasn't at 80 degrees Celsius
when we started heating it up.
The results were I think really, really very interesting.
Now I'd been against using cold water in a moka pot
because my concern was that you would overheat the coffee
inside the brewer as everything heats up.
And that's a little bit of a concern,
but actually something else really interesting happens.
The colder the water in your boiler,
the colder the start of your brew temperature.
As water heats,
and it can be almost any temperature,
some of it is evaporating,
that happens kind of all the time.
The hotter it gets, the more evaporates.
And I know that it boils at a hundred degrees Celsius,
but you don't need to boil it to have evaporation.
That evaporation causes a pressure to build up,
and at some point you have enough pressure
to push water through coffee.
The colder your starting point the colder the temperature
at which your coffee starts brewing.
If you load this thing with cold water,
with 20 degrees Celsius water,
then your initial brew temperature,
the first water to pass through coffee
was about 60 degrees Celsius.
Yes, it went up to about 120 degrees Celsius
over the course of the brew,
but the very start,
the earliest extractions you do were much colder.
So at 20 in you've got about 60 to start with.
And actually the same at 40,
it was about 60 to start with.
At 60 it went up to about 65.
And again at 80 it was about 65,
though bear in mind that 80 was not 80 in the pot
at the start of heating.
By the time we got to freshly boiled water
then our brew temperature was around the upper eighties,
very early nineties.
That's really interesting.
And certainly a good idea I think
to start with freshly boiled water
in the base of the whole thing,
because it means you start your brew
with a sensible brew temperature.
Now one thing I did discover on the brew temperature front
is that it actually if you boil the water in the base,
and then start to brew
that water goes from 100 to 106, 107 very quickly,
and you end up with a very hot start to the brew
perhaps hotter than I would really want
from a taste perspective.
So actually having the water in the bottom section
be more like 80 to 90 which is what you'd get
if you poured from a boiled kettle into a cold base,
that seemed to be the better result from my testing.
So far, so good.
I had a technique out there,
I have a technique out there,
and it does recommend starting with hot water.
So at this point I felt quite good.
I felt validated.
I thought this is going quite well.
I'm hopefully gonna prove
that my recommendations were right,
maybe learn a thing or two.
Very quickly it started to go sideways.
Grind size was our next round,
and a pretty simple set of experiments,
everything run the same way.
And we went with a Niche grinder
on what would be equivalent of like a 60 setting.
I know it only goes to 50 on the numbers.
A 50, a 40 and a 30.
What I expected to see is as we went finer,
and finer, and finer,
and got very close to an espresso grind
I expected to see a drop in extraction
as channeling starts to happen.
That did not happen.
The finer we went the higher our extractions went,
but then there was a twist.
We saw something else change quite dramatically,
and that was ultimately the brew temperature changed.
Now if you think about it this makes sense.
If you're building pressure
you need to build pressure against something.
Water can only exceed 100 degrees Celsius
if it's in a pressurized environment.
So when you make a moka pot
there has to be some resistance there,
some pressure to sort of resist against
to allow it to reach very, very high temperatures.
The finer you ground the coffee,
the hotter the brew was able to get.
Oh, and the quicker that it heated up as well.
So that was kind of interesting,
and a little bit unexpected.
The very hot brews didn't taste very good,
but they were definitely much, much more extracted
than the coarser ground brews.
Now a quick note on brew temperatures
while we're talking about this kind of stuff.
If you're starting with freshly boiled water,
and you're really building any pressure at all
the interesting thing
is that you're definitely brewing with water
above a hundred degrees Celsius.
The interesting thing about it
is that it doesn't necessarily taste bad but
really, unless you're doing something super super weird,
if you've built really any kind of pressure at all
even starting with freshly boiled water
you are brewing above a hundred degrees Celsius.
And you could be anywhere from 101 to about 130°C
being the peak temperature that we recorded
doing this whole thing
which is too hot.
So, yes, above a hundred is okay,
but no, really high temperatures are not good
and do give that kind of characteristic
moka pot harshness that we definitely wanted to avoid.
As for the actual heating setup
let me talk you through that because
well, for reasons you'll see later,
really kind of interesting.
The original pots that I'd sent to Gabor,
I'd sent those particular ones
because they were induction friendly.
And I thought if I could track the wattage
of an induction sort of top
I could really track energy in very efficiently.
The problem is that they only work on some induction tops,
and I do have an induction adapter,
but that easily becomes a bit of a problem
with a lot of the kind of
bench top induction cooking things.
So I ended up pulling out an old gas stove thing
that I have here,
and using the induction plate here
as a sort of heat diffusing plate,
and also a safe plate
to mount a kind of wobbly unbalanced thing
on top of a naked flame.
So that was the setup that we used
for pretty much all of the testing.
This is important.
We'll come back to it later.
The next test was heat power.
How much energy,
how quickly are we feeding heat into this thing?
With a gas burner you can't be super precise
so I set it for three different settings.
I set high, kind of max flame,
medium, and then the lowest flame that I could work with.
The results didn't quite go as I expected.
The high setting and the medium setting
actually both generated a similar pressure,
and a similar end temperature,
but they kind of got there in a different way
that was sort of notable.
In fact the high temperature setting performed I think
a little bit better.
We got more liquid out of the brewer
before it started to sputter and kind of overheat,
and do the kind of bubbling, hissing awfulness
that we will discuss in a little bit.
In the medium setting the same thing happened
a little bit earlier on
that I thought was just really interesting
and I don't necessarily understand why,
but it definitely did.
Now the best performing
from pretty much every perspective,
the lowest overall brew temperature was the low setting.
And so ultimately in all of this
I will recommend a low setting for your moka pot brewing.
Now what exactly that means is more complicated.
I promise we'll come back to it.
So let's talk about that kind of sputtering phase
that happens at the end of the moka pot brew.
Generally that kind of gurgling, angry bubbling
that's happening is considered bad.
And in all testing I think I can say it is bad.
And what I'd recommended previously
was that at you immediately stop the brew at that point
by running the pot under a cold tap,
and that works really well to stop brewing.
But I wanted to understand that stage a little bit more.
What's seemingly happening is that
essentially the whole system is so hot
that uncondensed steam is passing
right through the puck of coffee
all the way into the liquid phase on the other side.
And that's bubbling up,
and that's pushing liquid up very quickly
causing it to kind of spurt and spray out.
That phase where uncondensed steam
is passing right through the system
does correlate with very, very high brew temperatures,
and it does correlate to a very unpleasant taste.
What I noticed though
is that you would get sputtering starting
at different moments in the brew
depending on a number of different factors.
And this is the beginning of me
starting to kind of lose it with this brewer.
It was really hard to predict early on
when a brew would start to sputter.
To some extent it correlated to temperature
in lower chamber,
to some extent to pressure,
but not absolutely.
What I did know however
is that if we're brewing specialty coffee,
light roasted coffee,
then in that case we need as much brewed liquid as possible
ideally through the pot before we start to sputter.
If you do any real measurement of coffee brewing
you'll know that outside of grind
probably the second most important variable
is the amount of liquid that you brew coffee with.
Now my previous recommendation
to stop the brew at the point of sputtering,
well, that's actually not that helpful it seems.
It doesn't tell you how much liquid
you're supposed to produce in that period of time,
and it could result in someone stopping a brew very early,
and having ultimately quite an under extracted
and sour cup.
The question I really wanted to answer was,
how do we get as much liquid as possible through the pot
before we get to that superheated phase?
What can we do that is easy as possible to get there?
Now it's actually pretty easy to measure
the importance of the amount of liquid
passing through coffee.
Because with this setup what we could do
is measure a cumulative extraction.
It's a little bit annoying to do,
and in this case we took five cupping bowls.
You have to weigh the bowl,
and we would write the number of bowl,
and then the weight of the bowl
to 0.1 of a gram on the side of it.
And then you capture 20 seconds,
or maybe 30 seconds of liquid in each bowl.
At that point you can measure the contents of each one,
and with a little spreadsheet magic
build a kind of cumulative picture
of the extraction over time,
and over sort of the mass of liquid.
And you can see very clearly there is a correlation
between the amount of liquid
that you pushed through the coffee,
and the extraction that you get from it.
That is really important.
That is unquestionable,
and so controlling that
was gonna be incredibly important
to having a successful brew with this thing here.
So it was pretty clear that the next test had to be,
when do you cut the heat?
Not just when do you cool a pot down,
but when do you stop putting heat into the system?
And this resulted in discovery of a huge error in testing,
but also an interesting piece of learning.
Now if you remember the setup was we had the gas burner,
the diffusion plate, and the pot on top,
and then the tube coming off the side
dispensing the liquid onto a scale.
What I wanted to do with the first brew was cut the heat,
and what I wanted to do also
was lift the pot off the diffusion plate.
But because I still wanted to capture the liquid
into that jug sat on the scale
I lifted it maybe two or three centimeters up
above the plate.
I did not understand the impact of radiant heat
from the plate to the pot.
The brew though was super interesting.
We got a huge amount of liquid out
before it started to sputter.
If you look at the pressure here
you'll see that it doesn't peak particularly high.
And it rides very gently, very slowly down.
This meant that I think we got about 130,
140 grams of liquid out
before the whole pot started to sputter.
And previously getting to 120 grams of liquid out,
from 200 in the base, was considered pretty successful.
The problem was that I immediately realized
that I was brewing in a way
that I could not easily replicate.
I mean I could replicate it if I had a Franken-moka
with all of the data on pressure and temperature,
but am I telling people that they have to hold their pot
just a little bit above the thing as it works?
That didn't sit quite right to me.
And so I realized that the heating plate
is an anomaly compared to most people's set ups.
And the heating plate has a really interesting utility
to brewing a better moka pot.
I don't like this fact,
I didn't discover it on purpose.
This was an interesting little mistake.
Because here's the thing,
when you cut the heat completely
that pressure will discharge relatively quickly,
and you'll go back to kind of nothing.
Now you can on again off again, on again off again,
and that actually works reasonably well.
You might've seen a technique from the Wired Gourmet
who does kind of this.
He's aiming for a relatively low pressure inside the pot,
and kind of adding it to the heat just now and again
to boost it back up and go that kind of way.
It's an interesting video.
You should check it out.
I'll leave a link down below.
Some of the data we've collected here
does disagree with some of the ideas
behind what he suggests
but I think as a technique
it generally does work quite well.
The downside for me
is this idea of kind of surfing the temperature.
Is that necessarily good or easy?
Is there an easier way to do this thing?
And that's where ultimately
this little heating plate came in,
and proved to be just super interesting.
Firstly it did slow the heating of the pot slightly.
You know quite a lot of heat does get through them,
but it's slowed it a little bit,
and it acted like it was on a very, very low gas setting,
and that actually was really quite good.
But more interesting than that
it kind of acts like a thermal battery,
a thermal store.
Because you're filling it full of energy as you heat it up,
and you're filling the pot full of energy
as you heat that up.
As you cut the heat
the thermal plate is still discharging energy into the pot,
and that's really useful.
If you cut the heat just right
it lets you sort of have enough heat to keep brewing
without going on again off again, on again off again.
I dislike the idea that it might seem
like I'm recommending you buy one more thing
for making coffee,
but certainly for making moka pots
this was an accidental discovery
that's proved to be super useful.
Now this of course really just applies to gas hobs,
and probably induction hobs as well
where you're gonna be heating the thing the same way.
In an induction hob
you might be able to use an induction-friendly pot on it
and then instead of using an induction plate like this
drop to the lowest setting on your induction hob
for the remainder of the brew,
I suspect that would work quite well.
If you have an electric hob
where you have essentially a big element that gets a plate
hot on your cooking surface,
then that is going to be difficult.
Because when you turn that off
those tend to store even more heat
than something like a diffusion plate.
They tend to be bigger, heavier.
And so I would move the pot
right to the edge of one of those plates
just to have the smallest amount
of additional heat input that you can.
But ultimately those cookers
are gonna be the most frustrating to use.
With this scenario without a plate
you could still use gas and apply low heat,
and try and run it on the lowest, smallest,
very tiniest flame you possibly can.
But, and we'll talk about how to measure this
in a little bit,
if that doesn't work then getting the best out of the pot
may require something like a diffusion plate of some sort.
I've only used one and tested one,
and perhaps in future I should go and buy a bunch,
and see how differently they all act.
This one is pretty thick
so it'll hold a little bit more heat energy,
but this is what I've learned.
This is the testing that I've kind of done,
and the experiments, and the results that I've had,
and I wanted to share that with you as we go.
Next up is the AeroPress filter.
Now, if you go online and look at moka pot guides
a lot of them will recommend using one of these,
and they are interesting.
So you load your bottom chamber
full of freshly boiled water,
your coffee on top,
and then you turn your top chamber over
where the gasket is,
and this is sort of mesh basket base almost
to sort of strain the coffee,
you would place it there
so that any liquid going out of the brewer
passes through the paper.
In testing it did a couple of things that were interesting.
It did add a tiny amount of additional resistance
like grinding a little bit finer.
Which meant that on average
brew temperatures were very, very slightly higher.
And potentially correlated to that
we typically also saw a slight increase in extraction.
What I will say that was pretty clear cut
is that I did prefer the taste of these brews.
They were a little sweeter,
a little more complex,
just a little bit cleaner, unsurprisingly.
With the cost of these being so minimal
it seems an easy recommendation to make
to have a slightly improved moka pot brew.
From the way people talk about it online
I did expect a bigger impact on the cup and on extraction
which I didn't really see.
But, yeah, I'd still recommend adding this in
from a taste perspective,
from an extraction perspective.
However, don't be tempted to use two,
or potentially use a thicker filter.
I do have from the previous AeroPress testing
some of the Aesir filters which are much thicker,
and this had a noticeable impact on the brew.
It added quite a lot of resistance to the brew
as if the coffee was a little bit finer,
which meant that we did run notably hotter
in the brew process towards the end.
So from that perspective I wouldn't necessarily recommend it
because you might end up compensating with grind
to sort of have a more normal flow,
and a better overall performance.
And that will drop your extraction,
and may not work particularly well
if you're working with lighter roasted specialty coffees.
Oh and one extra little thing,
what we did notice with the AeroPress filter brews
is that they were a little bit foamier.
Not necessarily in a beautiful way,
and I could speculate as to why they might be foamier.
It didn't really change the texture, anything like that,
that foam dissipated relatively quickly,
but don't be surprised if you get
a slightly foamier brew from a filter.
Now I do briefly wanna talk about bloom.
I'd seen this mentioned in a few different recipes,
and recommendations online.
I didn't have great success here.
Now in terms of overall puck prep
I would grind the coffee into the basket,
settled, both horizontally or vertically,
and then prepped with a WDT tool.
So a fine needle to stir away any clumps,
help with the distribution,
tapped a couple of times.
I did not fill this thing fully, fully, fully to the brim
because I didn't get better results necessarily that way.
And the more dose you put in,
the harder it's gonna be
to get a really good even extraction,
especially from lighter roasted coffees.
Here there was enough coffee in the basket
that it would fill the space comfortably
without sort of giving opportunities for channeling,
or bypass brewing.
However, when it came to blooming,
the grind size that I was using
did not seem particularly conducive to blooming.
I was grinding reasonably fine,
not espresso fine, but certainly not filter coarse,
and so blooming it was nearly impossible.
You know it just didn't absorb very much liquid.
It was awkward.
And ultimately if I look at my extraction data,
and the taste involved
I'm not struggling for extraction here.
And yes I could grind a little bit coarser,
and maybe the bloom would help me out
a little bit there to compensate.
And maybe if I was trying to run a cooler temperature
at the end of the brew,
grinding coarser may help a little bit.
But certainly with the roasts that I was working with
which was sort of light specialty espresso roasts,
or sort of light to medium specialty espresso roasts,
I didn't really wanna drop the temperature any lower,
and I wanted to grind as fine as I could
to get the maximum yield.
So from my point of view blooming was interesting,
but also quite frustrating.
Now, as a quick aside,
I was thinking at one point
'cause I spent a lot of time thinking about this stuff,
how could you prevent the brew
exceeding a hundred degrees Celsius,
but still have enough pressure to brew?
Is that even possible?
And I did come up with one way,
and that
is to boil your moka pot.
Because what happens there is that essentially
you will heat the water in the base
to pretty much a hundred degrees Celsius.
It will reach reasonable pressure
cause there's a decent amount of evaporation happening
right below boiling point,
and that's what we saw.
The brew temperatures were always in the mid nineties,
the flow is nice and steady,
and well it was really pretty slow,
but we never exceeded a hundred degrees Celcius
at any point in the brew.
But the brew did take 10 minutes
because peak pressure was 0.12 bars.
Now that's enough to brew with
even with a relatively fine grind.
You don't need much pressure to get water through coffee,
but it really made for a very, very, very slow brew.
And even though the contact time was really very long,
the extraction was notably lower,
and the cup not particularly delicious.
So the good news is I'm not gonna recommend
that you boil your moka pots to make delicious coffee,
but you should know that we tried it,
and it was kind of fun.
Aluminum versus stainless.
Is one better?
We talked about the stigma around aluminum
in the previous episode,
there are no health concerns with aluminum,
but is it an inferior metal for heating
or brewing a moka pot with?
There was really only one way to find out.
What we need is thermal imaging,
what we need is predator vision.
So to achieve this we did what anyone normal would do
which is rent an incredibly expensive thermal imaging camera
to look at the difference in the metals as they heat up.
But quickly we realized there was a problem.
I should have remembered this,
reflective materials are really hard to read
on thermal imaging cameras.
They basically just reflect the IR from the room,
so you can't tell how hot they are.
So we did what anyone sensible would do
which is go and buy some heat proof spray paint.
And spray paint a little patch on each pot
so that we could see just how hot they were gonna get
on that one particular strip.
And we filmed them being heated from cold to hot.
This is just fascinating.
Aluminum is more thermally conductive
than stainless steel.
So I thought the upper chamber of the aluminum pot
would get hotter quicker.
But what we see is the stainless steel pot
gets hotter quicker.
And I don't really understand that, though
it might be the aluminum is a better heat sink, it's
distributing the heat more evenly.
But you can see on the stainless steel pot
there's that isolated pocket of warmth
at the base of the upper chamber,
and I don't really understand that.
So now you can see the base of the aluminum
is getting hotter,
and the upper chamber is now starting to get
pretty hot too.
We're still below boiling point on these pots.
And then the aluminum gets hotter, and hotter, and hotter,
almost seems to overtake the stainless steel pot.
I don't even understand what I'm seeing.
But what I do love to see is when they start to brew
you can see it in the stainless steel pot,
but you can't see it in the aluminum pot.
Because if you watch you'll see that green level
start to rise up and that's cooler liquid.
So clearly the liquid in the aluminum pot
is hotter than the liquid in the stainless steel pot.
And I presume the brew temperature is the same way too.
And if you look at both bases at this point
the aluminum base is much, much, much, much, much hotter
than the stainless steel base
even though the heat was running
on the stainless steel base for longer.
Maybe the stainless steel almost insulates the water
from an aggressive flame.
My gut is: stainless steel is better.
There's not a massive difference
in these two brewers in terms of mass,
they both hold the same amount of water and coffee.
These are 30 to 300s ish.
This one weighs 600 grams, this one weighs 700,
but it is a bit more thermal mass
especially in the lower chamber.
So that's gonna change the way
that the sort of water inside it is heated
once you take away the heat from the flame.
So back to the heating plate,
and back to the last of the experiments that we did
trying to get somewhere with better brewing.
What we were trying to do ultimately
was use the heating plate as that little thermal battery,
and the best results we had were starting with a cold plate.
Because if you started with a hot plate already,
and brewed back to back, it brewed differently.
And this is, just as an aside, this is this brewer.
You don't need to change almost anything.
A tiny change will manifest very obviously
in the temperature, in the pressure,
in the point at which it starts to splutter,
and get steamy and annoying.
It's really fussy.
Millions of people would tell you it's easy.
You just put coffee in, put water in,
you screw it together, put it on the hob, coffee comes out,
you take it off, you drink the coffee.
It's easy. Anyone can do it.
Millions of people do it.
But ignorance is maybe bliss.
This is such a fussy little thing, a frustrating thing,
and I think I'll be resentful for years to come.
Back on topic.
What we were aiming for was to get at least 60%
of the water that we put into the base
through the coffee before we hit the steamy angry phase.
That will give you a ratio of about six to one
in these particular situations,
and that's really useful.
That to me is pure flexibility.
With lighter roasts you need more liquid.
With dark roasts you'll get away with less,
and you can stop a darker roast earlier,
certainly well before it gets too hot,
and have a good tasting extraction.
I can't give you the exact numbers
that are right for every coffee,
that's just not how it works,
but this is just useful information to be armed with
when trying to get the best out of a brewer.
In our testing, generally speaking,
freshly boiled water into the base,
filter paper in there as well,
screwed together,
heat it up until liquid starts to flow,
and typically that happened at about .3 bars
inside the brewer.
At that point we've cut the heat,
and the residual heat of the heating plate
would continue to add some heat and pressure.
We might peak at about .6 of a bar,
but it meant that we would typically get to about
120 to 125 grams out before we hit the sputtering stage.
And if we looked at the extractions
they were very healthy at that point,
often above 23, 23 and a half percent.
Really quite strong as well
which we'll touch on in just a second,
but very well extracted, very tasty,
not super hot, not overly harsh,
none of the moka pot taste,
and really quite good.
Now as I said, all the testing was done
on the Franken-mokas which are 20 to 200 style brewers.
The 30 to 300 worked really well.
I would suspect the pressure would have peaked
a little bit lower
'cause there was just that bit more water to heat
with the energy inside the diffusion plate.
But with smaller brewers
I think you'd have a bit of trouble there,
and you might wanna leave it on the plate
for another 10 seconds and then remove it at that point.
Because it's probably enough temperature and pressure
inside there to get the last of that liquid through.
But if you left it on the plate the whole time
I think it would rocket up
to higher pressures and temperatures,
and you'd get the angry, steamy spluttering.
Again testing the amount of liquid that you get out
is a pretty good piece of feedback on your technique.
Did this go well?
Do I have at least 60% out?
If you're doing that,
if that's kind of how it's happening
that should still taste good,
and you can certainly play around with it lower than that
if you want a stronger beverage,
but you know what you're getting out at that point.
And like I said I was hitting very high extractions,
cutting it shorter,
with darker roasts I think would allow you
to have something that would go into milk really well,
and dilute well.
And actually, a note on dilution:
The brews that I was getting out of this
even at a six to one ratio were really very strong.
They were 3 to 4%,
really depending on a number of variables,
but often three and a half to 4%.
In those situations drinking them was still intense,
often from the perspective of acidity
which lighter roast tend to have a lot of.
Diluting them down with a little hot water
kinda making a little moka pot Americano
really, really improved the flavor.
The acidity became extremely balanced.
The sweetness remained pleasant and extremely present,
and they were just lovely to drink.
That would have been down to say a
1.5 to 2% strength drink
so still more texture,
still more strength than say a filter coffee,
but lovely, lovely balance,
really great flavors, great clarity,
just very enjoyable.
If you brew a brew that is good
but just a little bit sour still,
just a little bit dominant in acidity
just try adding some water to lengthen it down,
and just be amazed at the way
that it just balances everything out.
For exact numbers: a 120 gram brew
I would often add anywhere from 80 to 100 grams
of freshly boiled water just to lengthen it out
and dilute it down.
Obviously this is entirely about preference,
so you do you.
So it's time to wrap up the experiments
that we've gone through,
and what we might've learned,
and what it means going forward
into what might be the next video in the series.
Firstly though if you wanna win a Franken-moka
don't forget there's a raffle,
link in the description down below.
$3 or more as a donation
will enter you into that raffle,
and you could win one of these.
I'll throw in some coffee,
maybe some other random stuff just to be nice.
So please enter if you can,
support a great organization.
Back to the wrap-up.
I hoped that I would potentially
prove that my previous recommendations were good.
I'm only human, of course that's what I wanted.
That wasn't the case.
And I think I can't go from here to the next video,
and just say "this is the ultimate technique
that will guarantee you success."
But what I think the next video will be,
the next moka pot technique video will be guidance.
What you wanna brew with,
light, medium, dark roasted coffee,
the pot size you have,
the set up for heating that you have,
I can give you recommendations
I think to get you to a really delicious brew.
And a little bit of diagnostic tools
to help you improve it from that point onwards.
But I'm interested, what did I miss?
What did I not test?
What ideas, what theories,
what thoughts are you having, having seen
some of the data and some of the information here?
Does this kind of go with your experiences,
or is this totally against your experiences?
Let me know your thoughts, your feedback,
your comments down below,
but for now I'll say thank you so much for watching,
and I hope you have a great day.