- Today we're gonna bust some caffeine myths.
Now recently a company called Lighttells
made a relatively inexpensive caffeine analyzer
and so immediately I had to buy it.
It's in here.
Now I say relatively because it was still around $2,500,
but that's cheaper than anything else I've seen.
Now the reason I was so interested to get it is
because there's been loads of studies on caffeine,
but honestly, most of the time I haven't really trusted
either the quality of coffee they were brewing
or the quality of brewing that they were measuring.
And suddenly I could do a bunch of tests
and ask a bunch of questions
and get a bunch of real answers
that are relevant to me and the coffee that I drink
and the coffee that you drink at home or in cafes every day.
First of all, I'll show you how this machine works
'cause it is kind of interesting
and then we'll get into the really fascinating stuff.
We're gonna cover things from instant coffee
to espresso brewing to roast levels
and there are some surprises in this whole thing.
This is it.
I know it doesn't look like $2,500,
it doesn't look very exciting,
but I promise you it is.
The way it works is kind of annoying, if we're honest.
Turn it on.
That bit's fine and I'll connect to it with my phone
in a second.
But we need to talk about how you actually do
a single caffeine test.
And there, there's some bad news.
Each test requires this pack of reagent and stuff.
There's a chip, there's some pipettes,
and there's some reagent in there.
Let me show you.
There's a little chip.
The chip is what you insert into the machine.
All of this is single usage.
You can't reuse a chip, you can't reuse a reagent.
And so each test, each single test, requires this kit
and this kit costs £7.50 per test
which is wasteful and expensive.
So I had to make sure to make every test count
which we did.
So these two are connected and I can begin my test.
I'm gonna need to get a sample of coffee.
I happen to have some coffee just here.
These are kind of cool.
These are pipettes that allow you
to capture a very fixed, consistent amount of liquid.
That full straw section is what you'll always get.
And so we've got a full little tube of coffee there.
That gets mixed with this here reagent.
In it goes, give it a shake for 10 seconds
and then we just need to cover the reading area of the chip
with coffee.
I can hit start
and the analysis can begin.
And we've got a result.
We're gonna talk about caffeine levels
in a couple of different ways.
We'll talk about the total amount of caffeine
in a drink and we'll also talk about the caffeine level
per 100 milliliters or deciliter.
That's kind of how the little machine works.
Bear in mind that the daily recommended allowance
of caffeine for most people is up to 300 milligrams.
I did make a whole video about caffeine.
I'll link it in the description down below
but let's move on with that first test.
So the first test we wanted to do was filter coffee
versus espresso.
Was there a difference in how much caffeine you get
based on how you make your coffee?
If you took 18 grams of coffee
and you brewed it as an espresso, to say 36 grams of liquid,
but you extracted a fixed amount of coffee that way,
let's say 21% of the ground coffee was extracted
into the beverage, and then you made a filter coffee
with 18 grams of coffee, same coffee again.
But here you used 300 mls of water to extract 21%,
let's say.
If you compared those two identical extractions
was there a difference in caffeine?
Turns out, oh wow, there really, really is.
The average espresso in testing,
the whole espresso if you drank that whole double,
had 110 milligrams of caffeine.
If you drank that whole filter coffee,
again, from exactly the same amount
of ground coffee at the start,
but if you drank that whole beverage,
170 milligrams of caffeine.
That is nearly 50% more caffeine
in the filtered coffee than the espresso.
This absolutely blew my mind.
This was astonishing to me
because the extraction was the same!
I could imagine a little difference
but a difference this big,
I could not get my head around.
This needed further testing to try and understand
what exactly was going on here.
This led us to the second group of experiments.
Here what we wanted to do was track what was happening
with both coffee extraction and caffeine extraction
during the course of the brew
for both filter coffee and for espresso.
Now the way you do this is relatively simple.
You would make a coffee as normal.
Let's say you make a pour over,
but underneath it, you're gonna catch that resulting liquid
in five different bowls.
So you catch, say, 50 mls in the first bowl,
50 mls in the second bowl, 50 mls in the third,
and so on and so on.
And so you can slice out the brew into five parts
and you can do exactly the same thing with espresso.
So you catch the first, let's say, 10 mls in one cup,
the next 10 mls in another,
the next 10 mls in another.
And you can split it out.
Now you have to know how much your bowls weigh
and you can calculate then the mass of liquid
exactly inside.
You can then measure the concentration of both solubles
and caffeine and you can build a cumulative chart,
what's happening over time,
which is what I'm gonna show you now.
And we'll start with filter coffee
because I think that's a nice place to start here.
And so the first chart that I'm gonna show you,
along the horizontal x-axis, it has mass
and along the vertical y-axis, you would see extraction.
Now what you're seeing here is at the start,
the extraction increases very rapidly.
And if you look at the color of the liquid
coming out of the bottom of your filter cone,
it is much darker.
There's lots more solubles coming out at that point.
And you'll see as we progress the brew
and more water passes through the coffee,
that rate of extraction starts to slow down
and kind of flatten out.
You know the coffee coming through the cone
right at the end looks much, much, much paler.
Let's look at exactly the same chart,
but instead of total solubles,
let's just look at caffeine.
And again, mass along the x-axis,
total caffeine on the vertical Y.
And it looks very similar.
At the start it extracts really pretty quickly.
And again, as we start to run out of caffeine
in the ground coffee, that rate slows.
And so what you can then do if you want to,
it's a bit nerdy I know,
is you can then chart solubles extraction
against caffeine extraction.
And here you'll see that there's a pretty
linear relationship.
The more coffee you extract from the grounds,
the more caffeine you get with it.
Pretty simple.
But let's look at espresso
because that I think is where we see some changes.
So here again, same first chart.
Along the bottom we've got mass,
along the y-axis we've got total extraction.
And again, espresso extracts very quickly at the start.
That first liquid out is dense and gooey and delicious
and it gets thinner and kind of waterier as you go,
so the same thing happens.
But if you look at the caffeine versus mass chart here,
you'll see that it kind of starts to look
a little different.
The caffeine seems to lag a little bit
behind the total extraction.
And so when you chart out caffeine extraction
and coffee extraction,
you see quite clearly there's a big lag
in caffeine extraction in the early phases
and then it picks up speed.
- Hi there!
I just wanted to interrupt
because I forgot to say this in the video.
If you pull more like a lungo,
like a 3 to 1 ratio, a longer espresso,
do expect more caffeine
for the same overall extraction.
You'll see that from this chart, again,
caffeine is accelerating towards the end,
and so longer espressos do have more caffeine.
Not as much a pour over, but definitively more.
Okay, thanks, bye -
Now this particular shot was with a Niche grinder.
I'll show you a different chart now.
This one from the OPTION-O, the P100,
so are a bigger burr grinder,
and here this caffeine lag is way more obvious
which I think is really, really interesting, though
that grinder extracts very, very quickly
right at the start too.
So it feels like some aspect of caffeine extraction
is linked to contact time.
That's the only thing I could think of
with the kind of variable between these two things.
Is it that just espresso happens so quickly
that there's not enough contact time
to get the caffeine out,
even though there is enough contact time
to get all those good delicious soluble materials out?
That led to the next experiment.
For this one, we required the use of the trusty Aeropress
and the experiment here was gonna be pretty simple.
We were gonna take a traditional Aeropress recipe,
12 grams to 200 grams of water.
And what we were gonna change,
for a fixed grind setting, was just the contact time.
The kind of steep time initially before the swirl,
the settle, and the press.
And we did a bunch of different tests here
going from a 30-second steep to a 20-minute steep.
Broadly what you'd expect to see happen
with extraction, happened.
The longer your contact time went on,
the more you extracted.
This is news I feel to almost nobody.
We know that the longer something steeps in water,
the more stuff comes out of it.
However, the caffeine extraction rate
very quickly started to flat line.
In fact, once you'd brewed and steeped for two minutes
in that particular phase,
you didn't see any additional caffeine extraction
really happening regardless of how long you steeped for.
And so you don't have to worry
that having a really long steep time,
which can taste really good in say an Aeropress
or even a French press, that's not giving you more caffeine
than you otherwise would have.
It's seemingly having little to no impact
on the caffeine once you cross that threshold
of steep time where you're getting what you need out.
I don't understand this and I feel like this is
one particular area that needs loads more testing
but there's a lot more to talk about.
So we need to talk about instant coffee.
And this is one area - this is THE area where
I've made the biggest mistake
and essentially spread the most misinformation by mistake.
Now I'll give you an anecdote
that I've heard quite often, people often said to me,
"I used to drink instant and now I drink specialty,
I drink fresh coffee.
And I feel like there's way more caffeine in that".
And I would typically reply "that seems surprising
because instant coffee pretty much everywhere
is mostly made with Robusta, as a species,
which has twice the caffeine content of Arabica".
And I was also pretty confident that
during the extraction process that would've gotten
all of the caffeine out of the Robusta.
And so my theory had been,
my presumption had been there was more caffeine
in instant coffee than there would've been
in fresh coffee because fresh coffee was made
of better quality coffee that started with
less caffeine in there.
Then I did some testing
and it did not go the way I thought it would.
Instant coffee compared to a pour over
has way, way less caffeine in it.
This is a slightly tricky thing to say
because obviously the way that you make instant coffee
will have a big impact on how much caffeine is in there.
Now if you get a jar of Nescafe gold,
you don't have to, but if you did,
it will tell you on the side to take 1.8 grams
of instant and mix that into 200 mls of hot water.
They are proposing you a cup of coffee
that is incredibly weak, actually,
a 0.9% strength compared to a typical filter coffee
that would be say 1.3 to 1.6, somewhere in that range.
So they're saying: brew it weak.
And, you know, maybe for good reason.
What we wanted to do was actually have instant
be a comparable strength to filter coffee
to compare those two things.
So we then took 3 grams of instant
for 200 mls of water,
which then gave us a 1.5% strength beverage
at the end of it.
So how much caffeine are we talking about?
Now here, rather than talk about
total beverage amounts here,
we're gonna talk about caffeine concentrations
per 100 mls, per deciliter.
Instant coffee made the way they tell you to
had just under 40 milligrams of caffeine per deciliter.
If you made it the way that we might
to get the matching strength,
that would go up to 60 milligrams per deciliter,
roughly speaking.
A lot of the pour overs that we measured
were actually more like 80 milligrams per deciliter.
That means if you made two matching size cups
of industry standard instant
versus industry standard pour over,
you might have twice the caffeine
per serving in the specialty coffee.
This to me was shocking, it was astonishing.
And what I had massively underestimated
and kind of forgotten about was just how much
of those grounds instant coffee manufacturers
are extracting.
We tend to see a ceiling of about 30%
being the maximum.
Instant coffee manufacturers are able to go higher
through a number of processes.
They're just using way, way, way less coffee beans
per cup of coffee and then getting you
to make it pretty weak.
Now we did go out and test the cheapest,
strongest, harshest instant we could find,
presuming that to be the purest kind of Robusta,
and therefore probably the highest caffeine.
That was higher.
But again, at industry standard 0.9% strength,
that was still only 55 milligrams of caffeine per deciliter.
So still not near the caffeine strength
of good specialty coffee.
This has definitely been misinformation I've spread.
I apologize for this now.
I did not realize how wrong I was
but if you have a friend or colleague
that seems to get through like five cups of instant coffee
a day and be fine, well this is why.
It just doesn't have that much caffeine in it
compared to good fresh coffee.
As a side note, we did at one point
measure the concentration of a V60 brewed with Lavazza,
which is obviously some Robusta in that.
It's still fresh coffee.
How is the caffeine concentration there?
Yeah, it was over 100 milligrams per deciliter.
So you know, again, cheaper raw materials
and Lavazza Rossa does have some Robusta in it,
will have more caffeine in them.
So specialty is less caffeine than cheaper fresh coffee
but it's still more than instant.
The last test that I wanted to do for this video
was one that I get asked about a lot.
I was asked about it in the recent video I did with Wired
on their channel for doing coffee support.
And that is, is it true that there is less caffeine
in darker roasted coffee?
It a question you get asked a lot.
The reason people ask it is the fact that
caffeine sublimates, which means it goes
from being a solid to a gas at temperatures achieved
in the upper ends of roasting temperatures.
The idea is that as you roast a coffee dark,
you're driving caffeine out of the bean,
it's sublimating out,
and so dark roasts have less caffeine in them.
I was always highly skeptical of this
but I wanted to test it.
And so we took a coffee, one particular coffee,
we did a sample roast of it
to a slightly underdeveloped, under roasted way,
a kind of normal roast,
and then a dark roast into what's called second crack
which is a stage in roasting
that would be a measurement point for darker roasts.
You could go much darker than this
but I didn't really want to.
Then we would take each of those three samples
and brew them as a pour over to matching extraction levels.
Then we'd compare the caffeine
and the results were super, super interesting.
Turns out the dark roast filter brew
had the highest concentration of caffeine
and it was a pretty big difference.
So the dark roast brew for a matching extraction
in terms of total solubles was
72 milligrams of caffeine per deciliter.
The medium roast, traditional normal roast,
had about 67.5 milligrams of caffeine in it.
And the very light, slightly underdeveloped roast
had 62 milligrams per deciliter of caffeine in it.
So that's a pretty large swing there.
Now I think there's two reasons for this.
Firstly, the longer you roast coffee,
the less dense it gets.
Like that 10 kilos of coffee you might load
into a commercial roaster,
what you're getting out at the end of it
is going down the longer you roast.
So a light roast, you might end up with only 8.5 kilos,
with a really dark roast, you may only end up with,
say, 8 kilos of coffee.
Now a lot of what goes away is moisture
but other stuff does essentially degrade
and disappear out during the roasting process.
This means that to make up, say, 10 grams of coffee,
you would need more dark roasted coffee beans.
But this doesn't explain everything
because actually if you count how many
dark roasted coffee beans we needed for 10 grams
versus the the medium roast versus the light,
well medium to dark, you needed about 7% on average
more coffee beans to make up 10 grams of coffee.
But we were seeing an increase in caffeine
of around 8.5%.
So it wasn't just that you needed more beans.
That darker roasted coffee is more porous,
it's less dense, and I think part of that means
it's even easier to extract every scrap
of caffeine that's in there.
Conversely, that drop in caffeine that we saw
with the under-roasted coffee meant that
it might just be harder to get the caffeine out
from a much denser, less roasted coffee bean,
as well as you just need less beans to make up your dose
of coffee that you're gonna start with.
This I thought was super interesting
and it kind of goes with my own experience
and my own kind of theories coming into this.
So I was pleased to be proved right,
but I definitely didn't expect the swing
that we saw from light to medium to dark
in terms of total concentration.
A highlight of the video for me, a highlight of the testing!
Now one thing I do wanna acknowledge at this point
is that you'll see different numbers
at different times for the same brew method.
You'll see a pour over that seems to yield 65
or 70 milligrams in one case
and a pour over, same recipe, that yields say 80 milligrams
per deciliter in another place.
Different coffees do have different caffeine levels
in them and that definitely showed up in our testing.
What we would definitely do when we were testing something
was use the same coffee for say espresso and filter
or the same coffee for all of the tests
to try and isolate that variable.
But coffee itself is a variable.
Generally when we saw Ethiopian coffees used,
they seem to have fractionally less caffeine
than other coffees we used.
We didn't see a massive variance amongst high quality,
high growing specialty coffees
but we did see some variance
and the amount of testing we would need to do
to give you guidance there is enormous.
It's on the list, but it's enormous.
Generally speaking, I think we know that
caffeine is the plant's response to insects
and that the higher you grow coffee,
the less caffeine the plant tends to produce.
I think that's a good, very broad rule of thumb
that will absolutely have exceptions to it,
but it's a good place to start.
But yeah, know that some of the variance you'll see
in those final numbers is down to the fact that
the coffee used was different
'cause we wanted to test lots of coffee,
lots of grinders, lots of brewers,
all of that kind of stuff,
to get to useful actionable insights
about how you're gonna brew and drink
and enjoy coffee day-to-day.
Now, I know there's other tests you'd probably like me to do
and I want to hear about them down in the comments below.
What should I have tested,
what's left out there that you really want to know?
I'd love to hear your thoughts and your ideas.
And even if you don't have an idea,
let me know which of these tests was the most interesting
or relevant to you, which was the biggest surprise.
I have really enjoyed this video.
This has been a massive learning experience for me.
I've definitely been humbled by it.
I've been inspired by it.
It's been a ton of fun.
And I hope it is very useful and interesting to you.
But for now, I will say thank you so much
for watching and I hope you have a great day.