How to brew coffee like a scientist

It's 7 a.m. sun, rising in the sky, light shines through the window, hits my face. Open my eyes and roll out of bed, and then go into autopilot mode.

Without even thinking about it, I gravitate towards the kitchen, turn on the kettle, pour out some beans, grind my coffee. I grab my Chemex, it's a pour-over filter coffee maker, fold the filter paper, plug it in, and then I stop. For the first time in a long time, I'm not sure what to do next.

And what I can't decide is, should I rinse this filter paper before I put the coffee in? Does rinsing the filter paper make my coffee taste better? And I'm really not sure.

I'm actually quite confused. Here's why. A few days before, I was in the kitchen.

It was Sunday morning. My partner Sophie, she was filling up the water jugs to water her plants. Our cat Leo was running around.

Once she had turned off the tap, I started up a conversation around how we brew our morning coffees.

I learned from you that I need also to water the filter paper. And I saw you once not doing it. And so I wonder why.

Sophie brought up the fact that at some point, I had told her, yes, you should rinse the Chemex filter paper first. But then she caught me not doing it. And now she was asking me, do I or do I not need to rinse this filter paper?

I actually wasn't sure myself. I mean, I've been to cafes, I've worked in coffee roasteries, read blogs. Everyone says, rinse your filter paper first.

But equally, I've seen coffee videos online. I've even done it myself where, you know, I didn't rinse the filter paper and it seemed fine. And, you know, I could have taken the easy road out, play it safe, tell Sophie.

Yeah, listen, I was lazy. I was not doing it the proper way. I should have rinsed it.

Don't be lazy like me. But, you know, if I had done that, here's the problem. Rinsing the filter paper adds 30 seconds to my daily coffee ritual, which doesn't sound like a lot, but that's an extra three and a half minutes a week, an extra three hours a year, and possibly seven and a half days of my life left on earth.

I'm one of those people who loves to optimize everything. And let me tell you, I absolutely do not want to waste seven and a half days of my life wedding filter papers if I don't have to. Which is why I decided, hey, this Sunday morning, should we put it to the test?

Yes, sure. Let's do an experiment.

So we brainstormed a bit and decided the type of experiment we were going to do is one that Sophie uses in her work. She leads studios that develop mobile phone games.

Like an A-B test basically. So the only parameter that is changed is one has wet paper and the other doesn't. Let's do it.

Yeah, let's do it.

Let's get some water on the boil. And so I did this A-B test. I made two Chemexes, one where I had rinsed the filter paper first, the second I left it dry.

I didn't tell Sophie which was which. And then she took a sip of the first coffee where I hadn't rinsed the filter paper first.

Bitter, dark, or still?

And then she tried the coffee where I had rinsed the filter paper first.

Bitter, but not as bitter as the first one.

If you had to choose a method going forward, which would give you the flavours that you like the most? The second one here?

Yeah, yeah, it's less bitter.

And Sophie decided that the second coffee where I had rinsed the filter paper was her favourite.

So it is more pleasant in my mouth.

And there it is. Her experiment gave us our answer. What's your approach going forward when it comes to making filter coffee?

Make the paper wet, I guess.

Sophie decides that for her, you know, those 30 seconds every morning rinsing the filter paper, it's worth it. We had our answer. We could get on with the rest of our lives.

If it weren't for what happened the day after, I got up in the morning and I made myself another Chemex. And I made sure to rinse every bit of the paper. I was looking forward to this aromatic sweet soft coffee.

But instead it was bitter, harshly bitter. I don't get it. I made the coffee the exact same way.

Why was it now tasting so bitter? Which takes me to now. A few days later, here I am, stood in front of my Chemex.

I have my beans ground into powder. I have my kettle. Should I or should I not rinse this filter paper?

I am just confused, more than anything else, kind of lost.

You know, it's as if I walked into a forest. And I kind of lose the trail that I am walking along in this forest. And then before I know it, I look around me and all I see are trees.

And I have no idea which way to go to get out.

This is the moment I decide I need a framework. I need something, someone to help guide me out of my confusion, out of this forest.

Out forest.

This episode is the journey I went on to understand what does a good coffee experiment look like.

And it's a journey that was made possible by the sponsor, BWT Water & More. They make water filtration kits for coffee brewing at home, in the cafe. I myself, in all my experiments, use their Penguin water filter with a magnesium cartridge.

And I'm very grateful for their support because this journey transformed me. It fundamentally changed my relationship to science and the entire coffee industry.

Thank I'm James Harper, and this is The Science of Coffee, a spin-off series from my coffee podcast Filter Stories, and a journey into coffee's hidden microscopic secrets.

So I needed a methodology, a framework. I needed to do a test, an experiment, that would conclusively answer the question, should I or should I not rinse my folder paper?

And I got my answer during one of those ridiculously hot heat waves that gripped Europe back in the summer. I was sat in my studio in shorts and T-shirt, droplets of sweat trickling down my forehead. My fan was doing overtime.

And I was on a Zoom call with a man in Copenhagen, Denmark.

No, I have, yes, yes.

He had his laptop perched in the middle of a roastery. Behind him was a big roaster, tubes and stainless steel benches and big tubs of coffee.

Yeah, I'm Morten Munchow, founder of Coffee Mind.

Morten is a rare person in specialty coffee because he straddles two worlds. He comes from the craft specialty coffee world. You know, people like you and me, we love interesting flavours.

You know, we're all about good coffee. But what makes him unique is how tight he is to the world of academic science. And he runs a company called Coffee Mind.

Coffee Mind is a primary education company, but with my background, I just can't help to also focus a lot on science and scientific methods.

And he's partnered 13 times with universities to publish research projects in coffee. And it's there he came across a framework. A framework that I could also use to put my wetting filter paper question to the test.

This is the framework that's been used by sensory scientists for almost 50 years now.

It's developed by Rosemary Pangborn at UC Davis in the 70s. And she divided sensory science into three phases of inquiry. It's three phases and each phase answer one and only one question at a time.

And if you get a positive, you go to the next phase. If you don't get a positive, you simply stop investing.

And here it is, step one.

So the first question is, is there a difference at all?

So let's say I redo my rinsing the filter paper experiment and I decide, yeah, there is a difference. We then go to step two.

The next step is, what is the difference? And only in intensities, not preferences. Only intensities, intensities of the basic tastes and the intensities of the categories of our flavour wheel.

So now what you would do is measure how much more bitter does coffee taste when you don't rinse the filter paper. How much sweeter is it? How much more acidic?

What about the aromas? Are you getting more fruity notes, fewer chocolatey notes? So let's say I do these tests and I discover that wetting the filter paper actually lowers the acidity.

Okay, then we explore the third and final question.

Third phase is who likes what?

And so now we know that when the filter paper makes coffee less acidic, Sophie tries the two types of coffee and decides, I prefer it when it's a little bit less acidic. But me, on the other hand, I'm like, no, I like this acidity. I prefer it.

And then we would have our answer. Rinse the filter paper for Sophie, don't rinse it for me. But I'm getting way ahead of myself here.

Let's get back to the first question. Is there a difference? Because if there's not a difference, I ain't going to bother with steps two and three.

Is there a difference? When I thought back to those chemics experiments, Not as bitter as the first one. Yeah, of course there was a difference.

One of the coffees tasted more bitter. So it is more pleasant in my mouth. OK, so that's the first phase sorted out.

Yes, there was a difference. I was ready to move on to phase two.

Yeah, yeah, I've been there.

Until Morten told me a story.

It's very awkward if people ask the question, Can you taste the difference at all?

A story that would be any teacher's nightmare. This story made me second guess myself. So here's the thing.

Morten runs Coffee Mind, a coffee training academy.

I've been teaching more than 1600 students in small groups of six to eight in London School of Coffee and Coffee Mind Academy in Copenhagen and also on training centres globally.

And one of the main things Morten teaches is how to roast coffee. And you know, when he started Coffee Mind back in 2007, in those early years, he was teaching his students the kind of coffee law, the things that the community had always known, things he'd read in books and on the Internet.

I've been teaching people so many things.

And he told his roasting students that if you want to affect the coffee's body, you know, how heavy a coffee feels in the mouth, well, you can do that by playing with the development time. Now, development time is the time from the first crack to when you dump the beans out of the roaster. Check out my episode in this series on coffee roasting to learn more about that.

Now, back then, the common consensus was you have a short development time.

It's low. If it's long, it's low. And in the middle, you have the sweet spot for body.

If you want the coffee to have a big body to feel heavy in the mouth, choose a medium length development time. If you make the development time too long or too short, you know, the body is going to be lower. Anyway, a couple of years roll on by and a generation of aspiring coffee roasters walk in and out of his training academy.

And after a couple of years, he decides, I want to back up all this knowledge, you know, within the specialty coffee community with some academic science.

I took it to the university.

So he hooks up with some academics in Denmark. They explore the science of roasting and amongst other things, they test this idea around development time affecting a coffee's body. And guess what?

The professional panel couldn't tell you the difference.

This long-held idea about development time affecting a coffee's body, it failed the first step of Rosemary Pangborn's sensory science framework.

Nobody found anything. We even did a master's thesis only asking that question and proved that there was no difference.

But for almost eight entire years, Morten had been teaching that thing about development time and body as if it were gospel.

I was just, oh my god, and I convinced hundreds and hundreds and hundreds of students.

But it wasn't true.

It is a very humbling experience. That's why I feel that I'm version 2.0 because I understand that I can be highly biased if I'm not seriously self-critical.

I could totally see myself in Morten's story. Before Morten decided to test this development time and body idea with a university, you know, I picture him and his students gathered around his table. He's got coffees lined up, ready for a tasting, and he tells him, look, these coffees here have a low body compared to these coffees over here.

And his students taste the coffees, and they're like, yeah, yeah, totally, we tasted. And that's just like me and Sophie, when we put two coffees side by side, I told her that I had brewed one of them differently. And so we went looking for a difference.

And guess what? We found the difference. But was there actually a difference?

Had we just fooled ourselves into imagining a difference when there actually wasn't one? And Morten only discovered there actually wasn't a difference when he did the tasting tests to the same level of rigour as a university. And I decide that's what I want to do.

But I didn't actually know what that looks like. What a university is doing different to what I'm doing. So I went hunting around and I was very fortunate to grab the ear of quite the expert.

All right, let me grab, I've got to grab one thing just this minute.

So one day I was here in my studio in Berlin. It was getting late in the day, sun was low in the sky, my room filled with this beautiful orange glow.

And I got on a Zoom call with someone who had just woken up on America's West Coast.

Well, I am Becky Bleibaum and I am a sensory scientist. I've been a sensory scientist for a long time.

Becky has been in the world of sensory and consumer research for over 30 years. And a few years ago, she even branched out and created her own consultancy.

And my company is DragonflySci. We're located in the San Francisco Bay area. And we help companies try to make products better for consumers, understanding that sensory experience.

Now, Becky told me a surprising story. Basically, what happened, a coffee company reached out to her. They were like, we want to create a new coffee.

We want to know, like, what do consumers think of the coffee that's out there? What should we offer that's different? What do they want?

And so Becky's like, cool, cool, nice question. Let's start with the basics. We're going to get a bunch of coffees from the supermarket, your competitors.

There were two major brands and we did a discrimination test.

And let's see, can consumers even tell them apart?

And you couldn't tell the difference between two major brands, they were so similar.

Becky had the keys to a methodology. What test did you do to figure out that actually consumers cannot tell the difference between two supermarket coffees? And the trick is to do a discrimination test.

A discrimination test is a very simple three products on a tray, two of them match, one of them is the odd one out. Can you tell the difference between those three, right? Which two match and which one is the odd one?

And I totally knew what Becky was talking about because this is a triangulation. It is the basis of the Cup Tasters Championship.

It's a big event to prove like who is the best coffee taster. Competitors walk up to a table with eight rows of coffee and on every row, two of the coffees are the same, one is different.

And the winner is the person who can correctly figure out which is the odd one out in each of those rows the fastest.

It's also, by the way, a very fun competition to watch. If you ever go to a coffee trade show and have a cup tasting competition, check it out, because the results, the tension, the energy can be amazing.

So, I felt confident to put it all to the test myself. One morning I got up, walked into the kitchen, was greeted by Leo the Cat, and I brewed three Chemexes.

The first two Chemexes, I left the filter papers dry, didn't pre-wet them. But the third one, I thoroughly rinsed the filter paper. Could Sophie tell which was the odd one out?

Can you pick out the one that's different?

Those two are bitter. He's less bitter, that's all I can say. That one is different.

And lo and behold, Sophie got it wrong. The coffee she said was the odd one out, was actually one of the two, where I hadn't rinsed the filter paper. So I guess that's it.

I had my answer to step one of Rosemary Pangborn's three-step sensory methodology. Could Sophie tell there was a difference? Correctly identify the odd cup out?

No she couldn't.

But I have to say, actually, when I look down at my notes, I notice something kind of important. But I did measure when the water in that final pour, when the water goes below the bed of coffee. The coffee Sophie said was the odd one out, the one that tasted the least bitter.

The water finished draining through the bed of coffee almost a whole minute faster than the other two coffees. So the one that you said tasted less bitter and more acidic, that happened at 2 minutes 30. And this one over here happened at 3 minutes 24.

Yes, longer.

Longer. And when I mentioned that to Sophie, she speculated maybe my brewing technique was leading to different results.

Bitterness is different for obscure reasons, which I would assume is more on the way of brewing, temperature, water, etc.

Oh, this one kind of hurt. Sophie was accusing a man who makes podcasts about coffee for a living that he can't brew coffee consistently. And I was thinking to myself, no, no, it was consistent.

It was the same recipe. 300 ml of water, 22 grams of coffee, boil the water. Don't let it get too cold.

Pour the water in, you know, more or less the same way every time. But yeah, okay, look, yeah, it wasn't absolutely perfect every time. I'm sure I could have been more consistent.

But seriously, any differences in my brewing were tiny, tiny. How big a difference can they really make?

But it's when I took a train to Switzerland that it dawned on me. Oh, coffee is actually very hard to work with.

I hopped off the train, unfurled my Brompton bicycle, and cycled down the beautiful lake near Zurich, where most of the roads are congested with gas guzzling SUVs.

Anyway, I cycled past some plump looking dairy cows, turned off the main road, get up a steep little hill, and park up my bike at the Zurich University of Applied Sciences, where I met a coffee scientist. Tell me again, who are you? What do you do?

Hi, I'm Samuels Murkamp. I'm an analytical chemist. I did my PhD in analytical chemistry.

Samuels works at the Coffee Excellence Centre. It's a research and educational institute, and they also have a master's programme, which is available to everybody, including yourself, called the Certificate in Coffee Excellence. That takes you A to Z through coffee science.

Link in the show notes.

There is natural variation in everything. Some you can control better, some you can control not so good, some impact more, some impact less.

Samuels explained that when you do any experiment and especially in coffee, there is just a huge amount of variation.

The variability of all the processes in the coffee is significant.

He uses the example of making an espresso, where you use a tamper to press down on the coffee bed before you lock it into the espresso machine.

For example, he was talking about espresso, the way how you temp, the angle of the tamper, the force of the tamper. There is just so much variation.

And he explained to me, first things first, to do a good experiment, you need to understand where there might be variability in every little part of your experiment.

The issue is that sometimes you don't realize that something is not constant, or you think that it is, but it isn't. But you have to be aware, there is variability always.

So I think back to me brewing Chemexes in the kitchen, and I realize, jeez, I'm inconsistent everywhere. I mean, when I'm pouring water onto the coffee grind, sometimes it's an aggressive pour, other times it's a lighter, more circuitous pour. The water temperature!

I wasn't actually measuring the water temperature, so I don't know, maybe the water was going to be at 94 degrees one time, and another time 92 degrees. The tap water! So, you know, I use my BWT water jug to filter all my water, but I hear stories that sometimes the water company switches the water supply, and this new supply of water actually has a different mineral content, which can have an effect on the flavour.

But there were some places where I knew I was being consistent. For example, I used 22 grams of coffee in and poured a precise 350 millilitres of water. These were the crystal clear numbers my Le Tronc scale displayed to me.

But guess what? Those numbers, which I thought were accurate, there's variability in them too.

You know, you have your weight of the brew, you have your scale, it says 40.0 grams, but you have to be aware that there's a certain error in this measurement, so it could be 39.9 and 40.1.

Oh my lord! I was beginning to think, this is too much, this is too much! And Samo explained, yeah, it's tough, it's really tough.

So that's the fundamental point of this kind of experiment, is that everything has to be as constant as possible apart from the variable that we are changing.

But that's the challenge. If you want to do a proper experiment where you actually measure the thing you want to measure, in my case, rinsing the filter paper or not, this is what it takes. And Summer said, you know, you're ready to actually do your experiment if you're able to brew the same coffee over and over and over again, identically.

Now, can you make 10 brews one after another? And you're sure that they're completely indistinguishable?

And so when I get back to Berlin, Sophie was going to be away for a week for a business trip in India, and I announced to her, I will figure out how to make coffees identical. That will be my task. While you're away in India, that will be my task.

And to pull this off, I realised I needed pro equipment. So I buy a digital thermometer. I also buy a refractometer, which is a device that measures how strong a coffee is.

And then one Saturday morning, I sit down for two hours. Okay, let's get scientific and get brewing. So the plan is to make five coffees and make them all identical.

I use the same beans every time. Rwanda, natural Bourbon, roasted by 19 grams here in Berlin. I try and fold the filter paper the exact same way every time.

Nice sharp point at the end. There we go. Love it.

I try and keep the water temperature exactly the same. Oh, damn. And now I'm at 19, too low.

I've got to re-boil this water. I pour the water the same way every time. Ten seconds.

As accurately as I can. In the centre, not on the sides. I keep half an eye on Leo the cat.

Leo, you're in the middle of my science experiment. And stop her from licking the inside of it. Chemex.

Leo, you shouldn't be licking coffee. And in the end, I have five coffees. This is fun.

So many samples. How wonderful. Now, I did note, there were some small differences here and there.

I had slightly different water temperatures. Alright, so the temperature was 0.5 degrees cooler than the first two. One coffee took a little longer to drain than the others.

Like plus or minus one second for these last three batches. And what was really interesting is through this process, I really got to understand my measuring instruments so much better. There are many learnings from this test.

I understood that actually my scale stopped showing me 0.1 gram differences when it goes beyond a certain weight. My girlfriend's Harrier scale just does 0.5 gram increments. Not the most accurate.

My electronic thermometer gave me different readings depending where in the metal jug I was put in the probe. 93.3, 93.2. And I got to say, you know, as an experience, it wasn't that fun.

Especially working the refractometer. Oh, it was so annoying. And this measuring part is so tedious.

Ah, so tedious. Okay, last time. Even Lea was trying to make my life harder than it needed to be.

And now doing all my readings with a cat on my shoulder. But the point is, after all this rigmarole, I had five coffees that I was pretty happy with in terms of consistency. And then came the key question.

Are they identical? Well, my refractometer told me they were broadly similar. I'm in the square in the top part of the kind of ideal square for extraction in all these coffees.

But did they all taste the same? Oh, my God. All right.

So just tasted all five coffees. They are very similar, but also not identical. And as I tasted these coffees over and over, the results were just getting weird.

These coffees don't taste the same to me. One of the coffees would taste bitter and then it wouldn't. That's really weird.

I definitely perceived a distinct note of bitterness when I first tasted the first coffee. But now I've gone back to it, that note of bitterness has disappeared. Ugh, I was so confused.

And then it started to dawn on me.

You know, I think...

I think... I'm almost like, maybe it's not the coffee that are changing.

I had gone to all this effort to prepare these five coffees as consistently as I possibly could, only to realize that actually, maybe me as a tasting sensory instrument, I'm not consistent. And to help me better get a handle on this, I thought back to my conversation with Becky Bleibaum.

We've done coffee work for years, and you know, coffee is one of the most complicated products to work on.

My studio was saturated in late afternoon sunlight. Becky had just woken up on the west coast of America.

But the researchers have to make sure that the products that they have consumers evaluate or this next group of people evaluate, that are, you know, you really do control that experiment.

Becky told me so much good practice. If you're tasting with other people, shut up. Don't influence them.

Write down your observations before you start sharing your observations.

Make sure the coffees are at the same temperature.

So one's not hotter than another.

Put the same amount of coffee in every glass.

You know, you don't get more of one.

Keep the serving cups the same.

You serve them in the same cups.

And to be honest, I hadn't been doing any of these things. So initially, speaking with Becky, it was more just being reminded of this good practice that I already knew that I should do. But as she went on, I learned new things I hadn't been considering before, like the fact that when you do lots of tastings, you're going to get tired.

We also take rest intervals and then the next sample may not come for three to five minutes. So you have to sit there and rest and take a bite of cracker and a sip of water and, you know, just let your palate rest and kind of come back to baseline before you go on to the next serving.

And then she mentioned another thing that I wasn't really familiar with, first order effects.

We talk about balancing the order of serving, right? So each product is seen in each position an equal number of times. So we know the first order effect.

And this is the real phenomenon where the first thing we taste frames what we taste later. So let's say the first coffee is super sweet and then the next coffee is sweet, just nowhere near as sweet. And we might actually underscore how sweet it is because we had such a bomb of sweetness early on.

And then this leads me to, I think, the biggest revelation I had when it comes to doing any valid, robust tasting experiment, replication.

You have to be able to repeat. We talk about replication in sensory science because, you know, we never know if you can just fill out a scorecard once. It's like, okay, there's your answer.

But if you do it on multiple occasions, like two or three occasions for that same coffee, can you repeat your descriptions and your ratings so it takes prepping the products in a consistent way, evaluating the products in a consistent way, and then you get a very rich data set for which to correlate with so many things.

Repeat, repeat, repeat. And so over the next few weeks, poor Sophie is going to get bombarded with a lot of coffees. So first tasting.

That morning, Sophie had decided it's time to cut Leo's nails. Leo was not happy about it. While Leo was getting her manicure, I made three coffees.

And then I presented Sophie three wine glasses of coffee. They looked identical. Same wine glass, same temperature.

The first one was made with a Chemex where I had rinsed the filter paper. And the second and third coffees is where I left the filter papers dry. You have a glass of water, taste one, have a sip of water, taste another.

And just tell me, which one is the other one out? And Sophie, she got it right.

Acidity, maybe some sourness. This is more, just more bitter. It starts more with a bitterness.

I was really impressed. She picked the odd one out. But it also could have been random chance.

I don't know. I needed to do more tests. So a few weeks go by.

It's now the week before Christmas and we have plans to be away. Sophie is so distraught at the thought of being away from Leo for more than a day.

And she's installing a video camera to spy on the cat.

Anyway, I make my three coffees. And Sophie has in front of her three identical glasses. The first one, I did not rinse the filter paper.

The second, I did rinse the filter paper. And the third, I didn't.

But I try my best, so this has more a bit like sourness.

And she gets it wrong. The one that she thinks is the odd one out is one of the two where I had left the filter paper dry. And I just didn't have the heart to tell her she was wrong.

You get my points, there's no wrong answer.

Just to be clear, she's being sarcastic. I hope. Anyway, the point is, I'm thinking to myself, I need to do more tests, I need more data.

So the third time I ran the experiment was just after the Christmas holidays.

Leo had been looked after by some friends and they'd overfed her a bit. And she wasn't thrilled about being put on a diet. Anyway, I repeated the test again.

This time, first coffee was a dry filter paper, and the next two I rinsed them both.

The one in the middle tested much better than the other two ones on the side.

And Sophie got it wrong again. Of these three experiments, Sophie had got two of them wrong and just one of them right. And then I put poor Sophie out of her misery and a few weeks later did the fourth and final test.

It was a Sunday morning. Sophie was playing hide and seek with Leo the cat. And I brewed up three more Chemexes.

I rinsed the filter paper on the first and third coffees and I left the middle coffee dry.

And she got her wrong. That was it. I had my results.

I did four tests and Sophie only correctly identified the odd cup out once across four different tests. And the way I think about it is random chance, right? Like Sophie choosing three out of the four incorrectly, that is worse than random chance.

Now was it a perfect test? Absolutely not.

There are other parameters, but they are really hard to control again.

If I invested more time and money, I'm sure I could brew these coffees even more consistently.

In statistics, you need more than 400 actually tests conducted with the exact same parameters.

And it would be good to have a lot more data than just four tests. How about we repeat this experiment every day for the rest of your life and that way we'll have the absolute best statistical data set. You could spend 30 minutes every day doing this test.

This is where I set the boundary, James. I'm setting hard boundary here.

At this stage, what it says to me is that I don't know if rinsing the filter paper makes a difference. But what I can say with certainty, the way I make my Chem-Exes in the morning, there is so much variability in the way I make Chem-Exes. Even after being super, super careful, trying so hard to be consistent, the impact that rinsing the filter paper has, it is negligible.

You cannot tell the difference. There is too much other stuff going on. So in some ways, I failed.

But I love this result. I failed to get past the first step of Rosemary Pangborn's three step process. Sophie could not tell there was a difference.

Which in many ways is a relief. I feel with these results, I've clawed back seven days of my life. Even better, my carbon footprint.

I'm not going to be wasting energy boiling up 50-100ml of water just to wet some filter paper that doesn't need to be wet in the first place. This is a big win. Okay, it's a small win, but like, it has an impact.

I have managed to do one of the things I love most in this world. Optimising.

This journey I went on, led to one of the most profound shifts in me as a coffee professional. It made me realize, so many of the tastings I had done in the past, were using just pour methodology. For example, if the question was, does it matter if I shake the coffee grounds to level them when I'm making a pour over?

To get an answer, well, I would just do that, shake the grounds, make my coffee, taste it, if I like the change, there it is, I'll keep doing it. Sometimes, maybe, I'd even do a side by side A-B test, a comparison like Sophie and I did at the very beginning. But going on this journey, I realized that those answers were just not good answers.

They could be misleading me. That revelation blew my mind. Now, every time I see a video on YouTube or I see someone on Instagram brewing coffee in a particularly elaborate way, I think to myself, if I were to do a triangulation, controlling all my variables as much as possible, getting as many data points as I can, could I actually taste the difference?

And if there's one thing you take away from this episode, it's this. Next time you come across one of these questions, for example, should I add this elaborate step to my brewing process, try for yourself, do a blind triangulation a bunch of times and see what happens.

And me learning in this episode how to do a robust sensory evaluation, it was actually the beginning of an even bigger journey. A journey where I had to learn how to think like a scientist. How to think about evidence and theories.

What does it take to actually know something is true in the world of coffee? That is the journey I went on in the next episode, and I cannot wait to share it with you.

Thank So thank you so much for listening. If you enjoyed the episode, please consider telling your friends about it. It's hard to get the word out about podcasts.

I wish I had an algorithm like YouTube, but I don't. So think about who in your life is like the biggest coffee nerd you know, and share it with them. And if they already know about the show, share it with somebody else.

Another thing you could do is take a screen grab of your podcast player listening to this episode, post it as a story on Instagram, tag me at FullerStoriesPodcast, and I'll repost it and I'll be able to thank you personally. And while you're on Instagram, I have photos of the star of the episode, Leo the Cat. Come marvel at her beauty and feisty personality.

Now we're getting towards the end of this series of The Science of Coffee. In the next episode, I show you how you can store and grind your beans for exceptional flavours. And I travel to Zurich, Switzerland to speak with the R&D team inside Malcoenig, a world leading manufacturer in coffee grinders trusted by Borises Globally.

And they show me the intricacies of how grinders work and why tiny changes can have such dramatic results. And in case you missed it, in the first episode, I show you how you can become a better coffee taster. I reveal how our sense of smell and taste actually works and I get a bit metaphysical.

I use Microbeverage Systems' SP9 brewer to make many batches of a virtually identical coffee. I give it to lots of different people to taste. And yet, they all give me very different answers.

It sets me off on a journey to explore. When you and me taste the same coffee, are we actually tasting the same thing? And then I explore the science of roasting.

I visit Roest, a Norwegian company that's developing a fully automatic coffee roaster. I unpack one of their prototype roasters, the P3000, to see for myself the cutting edge technology that enables anybody, even me, to roast coffee exceptionally easily. And then I take you with me to Honduras to attend Let's Talk Coffee, a gathering of coffee producers and other coffee professionals from across the world organised by coffee importer Sustainable Harvest.

And I show you how organic coffee is actually produced and ask the question, why are there so few organic coffee farms?