All around us are the products of modern chemistry.
Drinking coffee is one of life's a pleasures,
a pleasure that cannot be duplicated by any other beverage.
Welcome to this episode of Weird Coffee Science.
And today we're gonna be messing around
and having some fun with "the buffer."
To explain this, I'm gonna have to talk to you about
water chemistry in relation to coffee brewing.
And lots of you are hoping
that this is gonna be that video.
The one that explains everything, the one that says,
which is the right sort of water chemistry
for the best tasting coffee, this is not that video.
I am gonna talk to you about a couple of key aspects
of water chemistry though.
But before we begin, I do need to shout out Scott Rio,
this is ultimately his idea.
He mentioned this kind of big idea to me
when he was in London
and it's nagged at the back of my brain
and I wanted to try it.
And I thought this was the perfect opportunity.
So let's talk water chemistry.
And I'm gonna do it in a way that I hope is simple enough
that if you don't care that much, it still makes sense.
And if you do care, you don't feel like
I'm basically lying to you.
Now for a long time, we talked about TDS in water
and that's, Total Dissolved Solids.
And if you look at say the back of a bottle
of mineral water, you'll be able to see
what kind of minerals are dissolved in that water.
Now, TDS is easy to measure.
You can buy a cheap TDS meter,
it'll tell you how much stuff is in the water.
And we use that for a long time to kind of tune our recipes
and tune our water treatment.
But people like Maxwell Colonna Dashwood were pretty vocal
in saying TDS is kind of useless.
It tells you that there's lots of stuff in there
but not what makes it up
and really to massively oversimplify,
there are two big categories of things
when it comes to coffee that are important.
The first are the minerals.
Things like calcium, things like magnesium.
These are necessary to help extract coffee flavor;
too much can be bad, but not enough can be bad as well.
With calcium and magnesium,
they each get involved in slightly different reactions.
So having a load of calcium will produce a brew
that tastes quite different to having a load of magnesium.
We're not gonna get too deep into that today.
The other key aspect of water chemistry
is what's called the buffer, the alkalinity of the water.
Buffering compounds when they go into solution,
produce both a weak acid
and a weak base in that solution, right?
So if you add an acid to them, that base reacts
with that acid and it neutralizes it.
That way, your PH doesn't move too much
if you add an acid to a buffered solution.
Now things like your blood have a ton of buffer in them
because of the pH of your blood moves much at all,
you're dead, that's very bad.
Now, in water bicarbonate,
acts as the buffering kind of compound here.
So you'll see a correlation between the level of bicarbonate
and its alkalinity, it's buffering potential.
If you took a filter coffee and you had a ton of buffer
in that water, you'd mute out a lot of interesting flavors.
It would be very boring.
Now, most of the time that we talk about brewing water
for coffee, we're often talking about filter coffee.
Now the strength of filter coffee
is usually between let's say 1.3 to 1.5%.
That's how much of that coffee is dissolved coffee
and the rest of the 98.7 to the 98.5, that's just water.
Filter coffee is not particularly strong at all.
Now espresso, well, that has a much higher concentration.
At that point, you're looking at maybe eight through 10,
even 12% strength.
Scott's suggestion was what if the amount of buffer
correlated to the strength of the beverage, right?
Having the right amount of buffer for filter coffee,
well, that might not be the right amount of buffer
for espresso.
What if you had, let's say seven times more buffer
in your espresso, what would happen?
Would that moderate the acidity of a super light roast,
a kind of filter coffee roast that when you brew it
as espresso is just brutally dominantly,
unpleasantly acidic.
So what we're gonna do is this, we're gonna take a coffee.
We're gonna take a Kenyan coffee
that was roasted for filter drinking,
and we're gonna make some espresso with it.
That's gonna be our benchmark
because we can extract that but that end result
as an espresso may not taste that good.
Let's start by getting an espresso machine.
Let's start by dialing it in
with just some nice brewing water and pulling shots
of this light roast filter roast kind of coffee,
and seeing how that tastes.
What we're gonna do here to start off with,
is take some reasonably be normal brewing water.
It's relatively low in both minerals
and actually relatively low in buffer
but that's okay because I actually want a benchmark
of what will be a very acidic espresso.
I'm gonna dose 20 grams into this machine.
I'm gonna pull 40 grams out in around 28, 30 seconds.
There should be a lot, a lot of acidity in the cup
which is what we want for this experiment.
I need some espresso.
We've got the all-important teaspoon,
we can give this espresso a little stir.
Ooh, that's got a lot of acidity.
That's got a lot of acidity in it.
This is exactly what I wanted to explore.
This is a great benchmark.
So this, there's a ton of origin characteristics here.
I can taste the coffee that went in there.
There is a ton of sweetness in this, but my, oh, my,
this is sour.
So, wow.
So onto our first experiment.
So what I've done and you just have trust me on this,
'cause I can't actually prove it to you
is I've changed the water inside this machine's tank.
And we've gone to a very high alkalinity water.
It's like 350 milligrams per liter alkalinity
which is about seven times more than you would have
in say good brewing water.
The question is,
if you're going at much higher concentrations,
if the concentration of espresso is seven times higher
than that a filter ish, does a seven times higher alkalinity
give you balance wherein you would usually struggle?
There's only one way to find out.
We have to make more delicious espresso.
So same thing, 20 grams of coffee in 40-ish, grams of coffee
out and around about 30 seconds.
That's our benchmark let's make it happen.
Looks good.
Acids definitely there, but it doesn't hurt my face.
Still maybe a touch more acid that I might want.
And a little harsh, little harsh, not bad,
not bad, better than before.
No, no physical pain as before.
Now, that's definitely interesting,
but there is one big problem.
High levels of bicarbonate
coupled with a reasonably high levels of minerals,
coupled with a hot environment equals limescale.
So this kind of water is much, much much more likely
to scale up a machine and cause you problems.
At this point, there's something interesting here,
but I'm not sure I'd recommend brewing
with high alkalinity water.
There is one more idea to discuss, but before we do that,
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Now I did have a second experiment in mind.
What I wanted to do was brew that original,
that kind of benchmark espresso,
but add the alkalinity in afterwards.
You see alkalinity is gonna affect
the extract of coffee, right?
It's gonna affect the liquid.
It's gonna affect the pH of that liquid.
It can affect it if you add it into the machine
but there's no real reason
that you couldn't just add it into the cup
and still have that buffering effect
on the acidity of the cup.
Now you're gonna need a lot more bicarb here,
like a lot more.
So I've made up a solution
just using the sodium bicarbonate.
So this is 2000 milligrams per liter of alkalinity,
that's a lot.
So what we should be able to do is just add maybe five grams
of that water slowly dilute our espresso
but then add a bunch of buffer to that drink
to see if it kind of mops up some acidity.
So what we're gonna need to do of course,
is to brew another espresso.
And give it a little taste just to give myself a benchmark.
Yup, yup, that's still, that's still very sour.
So I have my super high alkalinity water here
and I'm gonna add maybe five grams.
So does this work?
Yes, yes it does.
There's still tons of acid here.
Like there's still an overwhelming level of acidity
in the coffee that the buffer, five grams of this buffer
isn't gonna kind of mop it all up.
But goodness me, that's an interesting change.
Now I'm trynna work out, if it's in other ways,
changing or messing with my perception of the coffee.
I feel like there's been a textural change here.
I know we need to do this double-blind
and there's some flaws here,
but there's no question that has changed the experience
of this coffee.
It is more enjoyable to drink.
I don't know what this means.
I know that coffee science is weird.
I think we've got something kind of cool here.
I think we've got something really fun
and definitely something that you at home can play with.
Get some bicarbonate of soda.
And it's important that you get bicarbonate of soda.
Don't get baking powder that has other stuff
you want bicarbonate of soda, sodium bicarbonate.
That's what you want.
It's cheap, it's everywhere, it's in every grocery store.
Get some, you probably have some already.
Dissolve it in water.
I used about 3.2 grams per liter to produce a water
that had about 2000 milligrams per liter of alkalinity.
Now you could probably double that actually
and be able to then use less in your espresso
but this is so easy to do.
And I think you should totally do it.
The potential is kind of interesting here.
I'd be really interested to hear if you don't like this.
The point here is that you could have
like a little drop a bottle of water
that has a super high alkalinity.
And if you pull a shot, that's well extracted
but just that little bit too acidic,
one drop, two drops, three drops, a gram, two grams,
maybe that rounds it out, maybe that cleans it up.
Maybe you don't lose any origin characteristics.
Maybe you keep everything you like.
You know, historically we used sugar to fix acidity, right?
If you take lemon juice, if you add sugar to it,
it becomes pleasant.
The pH doesn't change, but the perceived acidity does.
Here, we're messing with the pH
and it changes the kind of acidity in a different way
than sugar does, right?
But it doesn't skew things,
it doesn't obscure things in the same way.
It's super interesting.
I want you to try it and tell me why this is a bad idea.
Tell me why this is stupid.
Tell me why this is wrong.
Tell me if it just makes you feel weird,
adding a little bit of bicarb of soda to your espresso.
I think with lots of coffees that won't work, right?
Like this is for light roasted coffees
that taste really good, but are just too acidic
when you brew them as espresso;
where that concentration is just overwhelming.
I would love love to hear your thoughts if you try this.
Thank you so much for watching, hope you have a great day.