BEAN TALKS – HOW COFFEE GRINDERS WORK

This weeks podcast is a special edition where Nick and Max talk about how to pick a coffee grinder. The difference between flat and conical burrs, and the impact of grind distribution and coffee fines on the flavour.

If you’ve wanted to know more about the mechanics of coffee grinder technology, this is not one to miss.

The full text of the podcast is below, but the best way to experience it is via audio. You can listen on the page here, in our podcast page, or on iTunes, Android or other podcast networks – search for ‘Bartalks Bean Talk’.

If you want to skip the banter, and just listen to the discussion on grinders go in about 13 minutes from the start.

Podcast Transcription

Nick

Why don’t you sing sing something from The Sound of Music? Say what to what? You’re still hot.

Max

I don’t know what the sad thing is.

Nick

There’s a volume button.

Nick

It’s kind of a guess here and you go into settings and. That’s it, oh, I’m playing something that’s worked. It worked. Yeah, it actually worked, I got through it all, I got through all the I got rid of all the background noise.

Max

hat is very impressive, man. Why do you work?

Nick

Something went wrong and something went wrong with it accidentally work.

Nick

All right, should we start the podcast? Yeah, I know. It’s just that’s the end of the podcast. We actually haven’t talked about anything, so we had a little bit of admin work. Admin work to do. Yeah, sorry about that.

Max

 That’s all right. I forgive you. Thank you. In my in my huge magnanimity. Yeah.

Nick

And you’re looking good. Looking very magnanimous there as well, Max. Thank you. I’m going to turn off my camera just to make sure we’re getting maximum good audio through this, I should say. You know what? I don’t need to do that. You know why? Because I’m recording, basically.

Max

Oh, yeah, you can you can actually just close. Fifty five thousand tabs you have open becauseI know you

Nick

 You are not even joking. I have happens all the time.

Nick

Normally I get on to I get on to like a video conference call or something. And I’m always two or three minutes late and I get messages on WhatsApp and they’re saying, Nick, are you, are you joining the call?

Nick

And I’m like, Yeah, I’ve just got to close a few more tabs for a but I think there’s just

Max

 I can’t find the tab ther is speaking to me saying is out of memory.

Nick

Hold on a second.

Max

I got 16 gigs of RAM and if I go and take a look on to file process manager, whatever it’s called, and it’s all chrome. So I’m actually switched to Edge just so I can get a little bit more memory out of it. I mean, the sensible thing to do would just be to not have all the tabs open, but.

Max

Yeah, but I do I do sympathize with that.

Nick

Yeah. I never want to close a tab. I might come in useful later and. Yes, you know, that’s how I think about it.

Max

That’s how, that’s how I fill up my shed and that’s how my my father filled up the whole house in Italy.

Nick

Yeah. Yeah. Have you heard of that Kubo girl. Mary condo. Mary condo. That was it.

Max

Yeah, yeah. Yeah. I think there is a yeah I think there is a place in hell that is reserved for me and she’s in it. She’s directing it.

Nick

She would be telling you to be following you around everywhere. Yeah. What are you Max. What are you going to do with that. You can keep that. Do you want to keep this. Are you going to use it. When was the last time you used it. Now I need it.

Nick

Now I’ll go away. I think you should thank you for its service and we’re going to throw it away. Okay, Max.

Max

No it is pretty and sparks. Joy, Joy,

Nick

this is going to be your hell. And she’s going to throw it away and you end up with nothing. But it’s all going to come back again the next day and it’s all going to start again. It’s not syphilis, not syphilis. That was you get that as well.

Nick

Who is the guy with the rock?

Nick

It wasn’t syphilis. It was Sapho Sophocles.

Nick

No, maybe not the guy.

Nick

The guy with the rock. Come on, I’m going to do this album.

Max

Yeah, it’s in the purgatorial. No, it should know it’s not. It was all done.

Nick

I’m just I don’t need to open up another tab if. If so, how do you spell it. Just coming up, syphilis. It’s that the first thing it suggests to me.

Nick

Why is it saying that this is for syphilis, rock and genre rock uphill forever pushing rock uphill forever. Who is that? Sisyphus . Yes, yes, yeah, yeah. You know, we’re on all these podcast networks now. And one of the things that I spent a day putting us on podcast networks, you just don’t know how much how much administration goes into doing that. And and on there, all of them ask, is this content, adult content?

Nick

And there’s either a yes or a no. And what you really want to say is not really. But every now and then, that’s what happened.

Nick

I just said no to everything, kind of lie, oh well, well, oh oh oh. Talking about lying, I’ve got to we’ve got to we’ve got to say some Coffee words and things because I’ve read somewhere that Google Google now indexes podcasts.

Nick

So what can we say that’s going to really get us to the top of the charts to repeat a few words coffee, coffee, coffee, coffee, coffee, coffee, coffee beans, beans, coffee beans, espresso, espresso beans, coffee espresso and coffee beans.

Max

Yep.

Nick

Anything else? Maybe we should add a few words in there, like sex, caffeine, sex, sex, coffee. That people search for normal demographic, that and pushing I don’t know anybody that that child friend, I’m just going to I’m just going to I just I’m just going to call in rule 42.

Max

Oh, rule 42 to. I think it’s no rule 34 that if I look that up,

Nick

hold on, I’ve got a book here and I need can look that up book. I got a book on rules. There isn’t a rule for what?

Max

Google. It’s just Google. It really. Yeah. School it rule hashtag 34. I’m done.

Nick

I’m going to do that right now. Everybody in the podcast.

Max

Will I do that in real time Urban Dictionary. Yeah.

Nick

Correct me if I said, oh you see the fact that I don’t know that reflects very your age and very badly on you.

Max

I’m sorry I, I am technically a millennial, uh, just borderline, but I’m technically a millennial, so I am allowed to know these things.

Nick

Max, let me ask an embarrassing let me ask you to just disclose something embarrassing about yourself. Why don’t you why don’t you explain embarrassing story? Why don’t you just give us some give us some dirt.

Max

hmmmmm nooo,

Max

I can catch you, you know, it’s amazing what people will do if you just ask them like, oh, something embarrassing, awkward and illegal. OK, well, there was this one time and off they go.

Max

no, I’ve been I’ve been trained. I mean, I could tell you, but then I would have to kill you. Everybody, listen to this, everyone.

Max

It’s so it’s so much work.

Max

I’m too lazy

Nick

Hey so today’s going to be like kind of different. A different podcast for us. Yes, sir. It’s going to be grinding.

Max

We’re not we’re not going to talk about coffee. Well, we’re going to talk about that. No, no, no.

Nick

The difference I, I got this friend who listens to my podcast.

Nick

Bless him. Michael, you know who you are, Michael. Well, obviously, I’ve just said your name, so you definitely a very good friend.

Nick

So she’s a good friend, is a sweetheart guy. And he sends me messages because he listens and he sends me messages every every Monday or something. He listens to it and he tells me what he likes or doesn’t like on the on the podcast.

Max

So he’s like, but does it listen to the whole thing?Because we can ask questions.

Nick

So he he listens to the whole thing and then he finds some way to to translate it into an insult, which I get the insult early in the morning after it’s published.

Max

So so that’s the being disappointed. That is the interesting thing is that.

Nick

Yeah. Yeah. He’s very disappointed that he’s disappointed. He’s disappointed in me. I don’t think he’s ever used the word disappointed. Don’t give him ideas. Normally he’s a little more brutal than that.

Nick

OK, but you like I take it I’m have to go back and change that flag podcasts. We’re going to talk about grinder’s, right. And yes. And so we’re going to I started making notes while about about yea I know. Said don’t get excited as only about one minute before you joined. As far as I got, as far as flat versus conical flatbreads versus literraly, I was going to, I was going to type out about 20 different things.

Nick

I’ve got that one line written out. So we’re going to we’re going to we’re going to have to wing it. Wing it, which is surprising for us. Yeah. We never do that. Do it. No, never.

Max

Never give me that.

Nick

We always have and we’re always honest. Yes. Everything. I never lie. Personally, I don’t think I’ve ever lied.

Max

Yeah. Actually I’m going to do that is I always like oh yeah.

Nick

OK, you’re doing the old you’re doing the old double double trick thing. Yeah I like that. Yeah. It’s very good.

Nick

So we’re a great team you see. I never lie and you always lie.

Max

Yeah. So you can never, you never know.

Nick

So we’re going to talk about, we can talk about grinder’s and why. Because they’re important and you know, you hear these things so hopefully hopefully if we don’t totally mess this up, this will be a really good introduction for somebody who just wants to know, like because it’s very confusing. Just wants to know, like what kind of grinder like what the thinks they should consider. OK, they should consider if they’re going to go and buy a grinder.

Nick

Mm hmm. But also have stuff in there that people who know a reasonable amount about grinders might still learn something from. So that’s what we’re going to do. That’s the challenge that I set for you to wow to me. So I don’t I don’t include myself in that challenge, obviously.

Max

Yeah, that’s actually specious. But that’s OK.

Nick

You notice that. But yeah. Yeah. So, so you know that that the thing is that was that we had a chat on Facebook a little while back in the groups like it was months ago and something I was going, oh, it makes no difference.

Nick

It’s just all marketing and that’s clearly rubbish, you know. But but no, no, it’s clearly rubbish. But to say there’s no difference between, like, a cheap grinder and a grinder costing thousands of dollars, you can you can argue whether it’s worth it to that individual. But you can’t say that there’s there’s no difference because obviously the difference in materials, there’s a difference in in also in the applications. The first thing the first thing if you’re looking at grind is you have to it’s not about what’s the best grinder, it’s what’s the best grinder for you and what you want to do.

Nick

Are you exactly are you grinding at home? Are you grinding frequently? Are you grinding in a shop? Are you doing single doses? Are you putting all your bean in the hopper? So so we’re going to we’re going to shed some light onto the not just the technologies, but when the technology makes sense for different use cases. So I like it. Yeah. Does that set the scene

Max

that sets the scene a lot.

Max

One of the most. Common things that you always hear whenever you joined a special word for one of the most common things you hear is invest in a grinder. Coffee machine can wait. Yeah. Which is I agree with it totally. Not completely.

Max

I partially agree with it because then then you can go crazy and people tend to go off topic and off target very much, which is I think it’s that is an issue. But we would get to that. So to start, what do you think? What’s the what’s the idea behind the grinder for you?

Max

So the first thing wait, so I asked the question without giving you any any sort of time to think. So what’s the first thing that you think let’s say we both know what we know about coffee and coffee and coffee machines and we know what we like in terms of coffee. What’s the first thing? If we didn’t have a grinder and we had to wire grind, it was the first thing that you would think of when buying one.

Nick

So for me, I don’t care about noise. I don’t really care about size as long as it fits into my cabinet. What I care about is consistency. So there’s some arguments about different flavor profiles that you get from conical burrs versus flat burrs. So you’re one of the first things you’re going to look at is you’re going to look at what kind of technology, specifically what kind of burrs you’re going to go for. But also also, as you know what, I’ll start with objective.

Nick

Actually, the problem with this discussion is yesterday yesterday I had a I was having a chat with a guy I just met and I said, oh, you know, you went to coffee. And he asked a simple question to which I realized I couldn’t give a simple answer. And he actually just said, you are talking to a friend. And he said, my friend was asking me, like, is there a difference? You know, is that genuinely a difference between, you know, the equipment?

Nick

Does it make that much of a difference? And I tried to start to explain and I realized that there’s so much and there’s so much technical data and and information that actually is very scientific and and it’s very hard to put into simple words.

Nick

But the best place to start, always complex problems, is knowing what you want. So what I would want out of my coffee is nice tasting coffee. Every single time I have to make my ideal situation, my outcome would be that I would have nice tasting coffee every single time and that it would be relatively simple because the reality would be get different coffees, different beans, and that would be relatively simple and quick to make the adjustments that I needed to make to quickly be able to get to the point where, as I was extracting the best out of that coffee that I could see if that’s my objective, how do I how do I meet that objective?

Nick

Oh, and then I was going to have that my first order objectives, my second order objective word. And this this isn’t what I’ve done, OK? But this is what I was doing. Again, my second order objective would be to maximize the amount of use I got out of the beans to maximize the efficiency of of of the grinding. In other words, I would really like to have something with very little waste. On it, and I would and I would like to minimize the danger of having of having old old grounds in the in the in the grinder, I would make it easy to clean and I would make it I don’t really care about speed and I don’t really care about noise.

Nick

I would make it easy to clean, easy to maintain, easy to easy to adjust and and make it very repeatable and want something that could once I’ve set it up, it would repeat it would repeat every single time. So I could just capture that that great shot consistently. That’s what I’d be looking for. How about you?

Max

I would actually. That’s what I always do, I always think how many cops I’m going to make per day. So what kind of throughput I’m looking for. And that, I think, is the most important thing that often is overlooked. And people don’t really think about it. And they end up buying these incredibly complicated and massive grinders that have so many controls and so many so many temperature adjustments and everything that you don’t really need if you are under a certain threshold.

Max

So you always have to think where you put your coffee grinder, for example, I’ve actually sold my Gaggia D90 to to a coffee shop to, uh, to a store that’s going white one. The white one is gone.

Nick

That was a beautiful machine.

Max

It’s I am actually really happy that they got it. And it’s I’m going to give them a little bit of advertisement.

Max

It’s it’s going to be in the earth. Coffee shop is called or an Earth restaurant. It’s in Petersburgh.

Max

And they’re going to to to put it up and hopefully they’re going to be making great shots aim, hopefully going to go and train them as well on it. So they got to get started fresh and they wanted to get also the grinders because I have a couple of groundlessly in my shop shop in my shed. And I asked them what kind of throughput do they have at the moment? So at the moment they make 40 cups to the maximum, which doesn’t justify getting ah, for example,La Cimbali or Fiorenzato  grinder that has a reservoir for ground coffee because you wouldn’t have the throughput to run out of that while you’re grinding new one.

Max

No, that’s that’s the important thing. I have these these ,La Cimbali one, which is amazing. It’s a it’s a great grinder. It’s going it’s got very big burrs. So it doesn’t heat up is very consistent. It’s a massive lump of steel. So it’s it’s great but is designed for Coffee’s that are so coffeeshops that are a high throughput. So for example, station bar as something where you have one customer after the other and you keep grinding coffee all the time.

Max

Now, if you have it in a coffee shop that does specialist coffee, that doesn’t doesn’t serve coffee, very often the coffee and the grinder is going to go stale by the time that a customer or just one. Mm hmm. And it’s the same thing when you get it at home. At home, there’s no point in having overkille machines like a grinder that can grind 100 grams of coffee in two minutes because you don’t need that. Right.

Max

And yes, it’s going to be consistent is going to tick all the boxes. It’s just that it’s inconvenient and utterly pointless. At the same time, when you’re at home, you can actually go for for a single dose one. So, for example, Niche , I think, had the best idea. The Niche Zero is I have my eyes on one of those expensive. I know. Five hundred dollars. This is too much.

Max

It’s just too much is wrong, but it’s something that you can grind on demand and do a single dosing. Mm hmm. That is something that is sensible. I’m doing the same thing with the with the Gaggia . I’m weighing the beans before I put them into the grinder. I know that it has low retention and then I just get everything out. It’s a bit of a pain. Obviously it’s it’s a long process. But when I’m making coffee at home, I’m OK with that.

Max

You have the same thing often you see ingroup in coffee groups, people with, you know, these overkilled grinders and everything, which doesn’t really make much sense. So that’s one of the things you should really I went off topic, by the way, a lot. It’s something you should keep in mind is how much throughput do you need?

Max

And then from there, you start taking your box because, for example, if you’re making one cup of coffee, you’re going to grind 18 grams of coffee, 20 grams of coffee, and then you’re done. So it doesn’t really matter if your grinder heats up, because in 18 grams, he’s not going to heat up enough to ruin the coffee.

Nick

Right, right. And actually, I want to talk about why Heat ruins coffee, because there’s a lot of different studies on that in the different opinions out there.

Nick

And and I’ve been doing some research into it and we’ll discuss that in a bit. But so you’d start with a with a place of like, OK, this is going to be at home. I’m going to make a cup of coffee in the morning, so I don’t need something for high throughput. What’s your next criteria?

Max

By next criteria is consistency of the grind. So for example, I prefer flat burrs because I’m five, because I want to see the person a little bit, I think. And I prefer to have a defined population of grind size instead of having two different populations, because this is the difference between. Flat burrs and connical burrs are a little slower, they they spin faster and they. They have a lower residence, time of the coffee into the into the ground, so it just grinds it and spits it through.

Max

And because of the design, they don’t have they don’t have big variability between the different grounds, of course, the residence time of the coffee. So if you have, for example, a clogged up chute, coffee chute, you’re going to have a lot more fine particles because it’s going to is going to keep the particles into the burrs more and the. Part of the the ground is going to grind the other the other particles, so you’re still going to have finer ground because they are they stay in the in the grinder for too long.

Max

Mm hmm. But if you if you’re able to get a consistent residence time. So basically the way I do it is I always take it off with a chopstick while it’s grinding. I make sure that it pushes it through.

Nick

OK, it sounds dangerous.

Max

 You need to be careful. We do not recommend that, you know, the chopstick is getting shorter and shorter

Nick

I’ve a distinctive woody taste to this

Max

but so that’s the way I do it. But you have to me to have a constant flow of coffee out of the coffee chute. And that’s why, for example, there is the, I think, decent me the flat burr that are vertical. Yeah, and what has zero residents in, that’s exactly the thing.

Nick

So let let’s let’s pick up on that point because, yes, now we’re talking about the design of the burrs . So the flat burr is normally horizontal and and what’s what’s actually happening.

Nick

Is that when the coffee is sucked in or brought in to these these burrs which have these sort of these sharp edges on them, the beans broken up into two processes, broken up through compression and sheering, and at first sort of crushes the bean and then shares them with the blades. And we’ll talk about why that’s important in a second. But it’s a flat it’s a flat burrs that sits horizontally. And as a consequence, there’s a tendency for coffee to get stuck in the chamber, not even tendency.

Nick

It’s what happens in the chamber. And there’s a number if you go for the more expensive machines, there’s a number of techniques they use to try to get those those that you out, including everything from little puffs of air to to like a knocker that tries to knock them out. But the mid-range machines don’t have that technology in my Eureka, which has 65 mil flat burrs, doesn’t have that. And I get quite a bit out the next day.

Nick

I have to take quite a bit of coffee out. It’s one of the, I think, mistakes that I made when I bought that machine, and that’s the reasons why I bought it. I’m still very, very, very happy with it. But one of the one of the downsides is that I have to get rid of quite a bit of coffee each morning that that’s stuck inside, said I’ve make sure I’ve got fresh grinds going through. The conical burrs are vertical and as the beans go through them, they have the benefit of gravity just helping the grinds fall fall through.

Nick

And you tend to have much less wastage from from a conical burrs than you do from a flat burr, right?

Max

That’s correct. So there because I’m assuming that who listens to us knows what these things look like, but just to describe them. So I flatboat you have two rings that have. Indentations on them and they meet with at an angle, so they have to have an angle and then there is a flat area with the indentations on it, when you adjust your grind, you push these two rings closer together or further apart. And this makes physically the maximum size of ground that you’re going to have.

Max

The bottom one typically is the one that spins and spinning. Puts throws the coffee on the sides, and then they get captured by the angle between the two little burrs and then that steel again with centrifugal force gets pushed between the flat in the flat part of the burrs. And that’s when the gets then ground in the flat part. And from there, since it’s spinning, it gets shot out. And in there there are two or three or four. It depends what machine you have.

Max

Wipers, sweepers, which are typically lumps of metal that are very close, they rotate very close to the edge of the of the chamber and they move away the coffee and they they they push it to the sides. And only on one side there is a hole. And that’s your way where your coffee shute is and it gets basically gets flung out of the of the chamber. And that’s why it’s important to have the chute with a constant flow of coffee out, because if you get stuck, you’re going to have the you’re going to be it’s going to be impossible for the for the the sweepers to.

Max

To throw the coffee out and it’s going to block everything into the the chamber and between the two burrs and so the coffee grounds are going to act as a as a as an extrovert. So you’re going to have a finer grind.

Nick

And when you twiddle your your your adjustment knob, what you’re actually doing is moving those burrs closer or further away together to make a finer or a course grind. And that’s where it becomes important that those burrs are aligned exactly level, because if you can imagine, if they were not perfectly level, you’d get areas where bean would be crushed to a different size than than another bean. And and then you’d get an inconsistent ground. Yes.

Max

That they actually they get aligned when there is coffee in it. So, for example, flatt burrs are not very good for a single dosing because they rely on the coffee on the top to push the coffee in the chamber.

Max

Onto the onto the bottom plate and then the bottom plate spins it away when you have a little coffee, what you have is called the popcorn effect. So you often will see that the last few beans, they’re going to jump out of the of of the grinder a lot. You have a lot of that will keep them from bouncing out. But still, it’s going to be different dynamic.

Nick

And actually, I did read some tests that show that the coffee, if you if you single dose on a flat burr, the coffee is is different from if you’ve got a whole bunch of beans in the hopper.

Max

Yes, that’s correct. That’s what I do. Actually. I single those in a flat burr, which is I know it’s not ideal, but I know that it makes it makes are the right size. Ground, because because of the burrs, the conical burrs , on the other hand, you have instead is not you don’t have the same thing, you don’t have the same the same system. You have an external bird that is it’s basically it’s a big lump of steel.

Max

That’s not the way to describe it with the channels cut into it. Like screw, like not a screw. What is that? That shaped like a shell? Kind of.

Max

They go in a spiral and explained,

Nick

like, if you imagine like a muffin thing, what you call a muffin is pieces of paper that hold your muffin. Yes. On the bottom cut out. It’s that fat shape. Yes.

Max

Or the since we are in the coffee business like like a filter. Like a folded up here above 60 filter similar to that.

Max

But they are in a spiral and that is the one that doesn’t move inside it. You have, you have a burr that actually spins and it goes, it goes in from, from the bottom and it’s got pretty much it looks like like a drill bit if you want to simplify it, it looks like a drill bit and it’s it’s conical. So again, you have the same system, you have the bottom burr that you can push closer. Sorry, you have the top burr that you can push closer or further away from the bottom.

Max

The. And that makes the maximum grain size that you can make, however, because of the design of the of this thing, they don’t get as close as the conical burr sorry as the flat burr. And they rely on the rest of the coffee to make the grind because you can’t you can’t physically have them so close because they wouldn’t be able to turn anymore. And these causes. Because there’s two main grounds to be to be made to link to main population sizes to be made a large one and a small one, so you will have a slightly coarser ground that is going to fall right through.

Max

And this one is going to help you to grind some of these into a finer ground, which is what you use normally to make espresso. So instead of having one single population with a certain distribution of of course, so you you have particles of one micron plus or minus one in the flat burrs. In this case, you will have two populations, one that is like three microns and one that is a point five microns with their with their own distribution.

Nick

Right.

Max

And you mix them together and you obtain espresso because they will anyway be mixed. And so they will form an homogeneous solution, not a solution, and homogeneous distribution dispersion into the pot, into the filter.

Nick

Well, that that’s interesting is one of the other things I heard or I read was that the conical burr, the bottom one, sits directly on the on the motor, if you like, a drill drill bit. And and they said that introduces a challenge for that burr to remain consistently flat spinning because its vibration, which means it introduces it’s more likely to introduce a variance in the grain size. And indeed, one of the one of the criticisms, one of the observations from from people you used and I’ve got both, I have to say, I’ve got both grinders in my kitchen.

Nick

I’ve got to grind this one with conical on the flappers. And you do notice that the grind coming out from the conical birds are tend to be clumpy, a bit clump here than the ones coming out from the flapper.

That’s for different reasons, though, that there’s, well, the whole clumping thing. And this is something we can talk about that next about the science of actually coffee going through the ground. But did you have a should wrap up there talking about the about the conical, the difference between the conical and the flat?

Max

Yes. So that’s pretty much it. That’s how they work.

Max

So you’re going to have different different distributions of the of the size of the sizes of the grind. That doesn’t make any difference when you make coffee. At the end of the day, it’s how it tastes and how easy is it for you to grind it, to dial it in?

Max

Personally, I prefer the flat ones because it’s more defined. So I know that I’m changing the size, the distance between the two burrs, and I know that that’s the maximum size I’m going to get. And that’s pretty much all the size I’m going to get when you when you change the step. And that’s also another story that I think we should also touch on. When you change the setting, you change your your medium distribution. So you change your medium size, medium size with with its own distribution when you have something that is made into a step less mode.

Max

So of of, of course, coffee grinder are engineered to be different and to to have difference that you can appreciate between one step and the next one. Lots of people tend to turn a step by stepped grinders so grinder’s that have no and an actual step between the two grind sizes fixed at their fixed movements.

Nick

So you go from one to two to three, you don’t get one point two, one point five, one point seven is one, two, three, four and so on. Yeah.

Max

And the reason for that is because when they are engineered there is quite a lot of study behind it and what they do when they engineered them, they make sure that the the difference between the two steps is statistically significant. Because if you if you take if we talk about the size distribution range, you never have one size.

Max

You will always have a Gaussian distribution, which I got some distribution is a bell curve you take if you take your pencil and you draw a bell.

Max

So you go from zero, then you go towards the top and then and then again, and it’s symmetrical, that is your distribution of coffee grounds that I don’t know, to be honest, what kind of variability you have is something I wanted to do at work. But I don’t I can’t. I still want to work there.

Max

So but what what they do when they design these things, they know that their size distribution range is X. And when you change from grind one to grind two, you can actually tell the difference because the the the median of the distribution, they are apart. If you put a step in between them, what you’re actually seeing, what you’re convinced that you’re seeing is is just your own conviction. It’s confirmation bias because there is no statistical significance, statistical difference between a ground one and a ground one point two because of the uncertainty, because of the residence time of the coffee in the grinder, because of the heat produced over time, that because of the heat of the day.

Max

So. Don’t bother. Personally, I would say don’t bother converting a step grinder to a stepless version of it because you’re wasting your time and energy.

Nick

Well, you say that, OK, but I like my stepless grinder, and I have both, and I operated absolutely fine with a step grinder. I enjoy the stepless grinder because it makes me feel like I have total control. But also I’ll argue, even though it’s probably I have no rational reason behind this argument, I’ll argue that when you put different beans in there, finding the perfect the perfect grind size I think is more fun and possibly possibly easier if you’re able to turn the knob to exactly where you want it to be, rather than saying it’s between a two and a three.

Nick

I have no evidence to back that up. But what I do have evidence to say, and I think this is an important thing, we talk about grind size. And actually you mentioned the bell curve, which is one of the most important one of the most important points leading up to understanding. If you really want to get grind size, you have to understand that bell curve and you have to understand that you’ve got fines on the left. We’ll talk about what a fine is in the second.

Nick

You’ve got your your average grind size, which is at the top of the bell curve or around that statistical, you know, that average. And then you’ve got the sort of the big lumps that come out on the other side, the boulders that come out on the right side. Yeah. And there’s been a lot of studies about and this is where it gets really, really complicated. But but but it gets a lot of studies about the importance of fines in a coffee distribution and the effect of boulders.

Nick

So you if you to have all of your so you to have all of your coffee made up without any fines whatsoever, you’d actually have a disgusting cup of coffee because apparently, apparently the flavour comes from the fines and the the grind side and the reason for that. So let’s take a step back for a second and say, well, how does how does flavour get into my cup flavor gets into my cup in a very short period of time in espresso, because you’ve got hot water coming into contact with coffee grinds.

Nick

And if you imagine that that water has to, has to, has to to invent a great word that I can say something like solubility or something that still has to be soluble ised, Max. So that’s a word is a word now. Yeah. You have to you have to dissolve some of that coffee into the water. That water has to take some of that flavor out.

Nick

And when you are if you imagine you’re putting coffee into a French press and you’re letting it sit there for nine minutes or something, the coffee grounds are slowly releasing their flavour in that hot water or if it’s cold brew over, say, 10 hours, it’s slowly releasing and and the water is by immersion absorbing.

Nick

Now an espresso. You’ve got twenty five seconds. Thirty seconds. Right. So you don’t have that same process that’s part of the reason why you grind finer because you want more surface area effectively.

Nick

That’s exactly the thing. Right. A surface area. However, even the surface area of a of a quite a fine grind is not enough to pull the flavour out. The flavour comes from the fines which are fine is I think I mean, they some people talk in terms of something that is that is point one micron or below. I can’t remember the term some people talk about in terms of size, but others have said, well, actually these things aren’t a regular shape.

Nick

So sizes doesn’t makes sense. It’s more in terms of literally the number of of of of how exposed the cell is in the coffee. So you’ve got anyway, the point is you got like almost like coffee dust. You can have very, very fine particle that’s come through the process of grinding where it’s been compressed and and a fine is produced from that process. It’s not the normal grind. It’s it’s a it’s a byproduct almost of the grinding process you create these fines the water hitting the fine, basically has immediate access to that whole particle and is able to extract the flavour very quickly from it.

Nick

So then the question comes, well, why do you have the grinds? Want to just pack your basket full of these fines and have a machine that makes the fines? And the answer there is that if you had a basket packed with fines, you would not be able to have the water pressure push through. It would be too fine. So what your. Actually, doing by having that distribution curve is having a mix of of coffee granules, coffee of of of ground coffee, coffee grounds that are a size that allows the water to flow through with a balanced mix of fines that the flavors extracted from.

Nick

And what you’re looking for is that magic number, that magic balance that the water is going through, the flow rate of the water is going through at just the right level. And there’s just the right amount of fines in that basket that you’re extracting the flavor for that period of time. And that’s actually what you are trying to achieve. So so when we understand that, then you go back to the grind of technology and you’re like, oh, OK, now I’m looking at the grinder.

Nick

And what the function it performs is that this is a little bit more complicated than I thought. I just I just thought it was like like, you know, I could take a hammer and achieve the same thing. Well, you know, not quite. It’s actually it’s actually a fair amount more complicated, right?

Max

Mm hmm. Yeah, that’s correct. And that’s the same thing of the conical versus flat because flat you have one distribution and. You have you also have the fines and the corse, but they are more tied together, right? And normally to have espresso, you you grind courser if you pass me the term. In a flatter than you would in Aconcagua in terms of distance between the the the birds, because the flat the flat bird will create.

Max

Finer particles in one distribution, while the conical one we create very fines and course at the same time. So you have the same effect, which is basically to have a certain a certain flow rate through the coffee, through the coffee grounds, but in obtaining the same result with two different approaches. That’s what that’s what’s happening. And again, it’s totally dependent on what kind of use you have. You want to do because again, if you want, for example, to do to be able to do.

Max

French press, same thing. I went to the French press was calling conical burr is probably is not the is not the way to go. Because it’s not going to grind. That quite consistently at that size, they’re very good for espresso grinding, but not very good for a larger one because you’re going to have too many fines. So you’re going to have a lot of stuff floating about in your coffee while with with a flat burr. You select your your size and you have it.

Nick

I have to say, I mean, moving from a conical to a flat burr is a lot more maintenance on the flat burr. My conical burr was was machine, which was a sage. Oh, they call them Breville in America. But I figured what the hell is called or something pro a thing. And that, you know, literally you take the hopper off, you stick your fingers in the guts of it obviously, and making sure it’s unplugged first. And there’s a little there’s a little metal ring.

Nick

You lift it up, you twist it, the burr comes right out and it’s very lightweight. That’s the other thing, that lightweight and lightweight, because, of course, you don’t need the small. They’re smaller, they spin faster, the smaller and and and because the burr are smaller, you don’t need a bigger engine to move them. And so the whole thing can be a smaller, smaller piece of equipment. So as a consequence, you can pick this thing up with one hand.

Nick

You can sort of brush all the guck out. It’s very, very easy to clean. And but, uh, but I prefer the coffee taste from my flat burr. So as soon as I started using it, it was it was much more like the flavor I was getting at my shop. And, um, and I would say I wish I could get some I could get some remarkable results from from that grinder, from the conical grind of the sage.

Nick

I could get some remarkable results, but there was just kind of a more smoother. And that’s the only word I think I could use as I was trying to find a clever word that would make me sound really smart that I could use to describe it. But overall, it was just a little bit more. Maybe I say balanced, but I would just say smoother. The results I get from from the espresso made with the flat burr. And so it does make a huge difference.

Nick

I would say the grinder you use, it does make a huge difference for me. The taste was was noticeable immediately.

Max

Yeah. I agree with you that it’s it’s the same for me. I prefer it’s in my head that I’m admitted to it. It’s in my head. But I preferred that one because I have the conical burr in the in the Gaggia Paros. So that has a built-In conical burr grinder, which is actually a very capable grinder. Just doesn’t work for me, some coffees, to be honest, some coffees, actually, they came out really nice because you can you can afford to grind finer, so you probably you’re able like that you’re able to pull out some of the.

Max

Very gentle flavors, like, I don’t know, like those very light fruits, like banana flavors.

Nick

They would say they say that conical burr have a bunch of flavor. That’s the word I’ve heard. Used to have a punchier, uh, flavor profile that they produce.

Max

And that is most likely because because you’re able to to produce more surface out of it.

Max

In a way. That’s probably why you’re more efficient in extracting. While not sacrificing the flow, the flow rate is another thing that I just wanted to point out. A lot of people tend to tend to measure coffee in terms of strength, so they use a refract ORM today to say, oh, this extraction is perfect. Well, I don’t agree with that because it’s not only in terms of strength. So how many how much non soluble material you have in your coffee?

Max

So how dark is your coffee? But it’s also a matter of how efficient you are in extracting the the the soluble material and the flavors which you’re not going to see that effect ometer. You’re a fractometer you’re measuring. How turbid is your solution?

Max

Mm hmm. And it tells you that in your solution there is, I don’t know, five percent solids. And that’s it. That tells you that you’re in the ballpark. But then it doesn’t tell you if you for example, if you extracted efficiently some of the acids.

Max

Because it’s about you’re not going to see them in the fractometer.

Nick

Well, yeah, OK, so I read a I actually have, um, I can’t I can’t speak with any sense of authority on that particular area. What I can say is that I have noticed that that that some people are measuring the quality of the of the grinder by the amount of TDS or total solids that they get out in a fixed period of time. So it was quite an interesting experiment.

Nick

And I get what you’re saying, and I don’t know whether this is this is related to it or not, but they did it was actually a really interesting study. And we should probably sort of wrap it up in a minute. But it was a really interesting study because what they did was they said, well, rather than trying to work out, you know, the quality of the output, how do we work out the quality, the output, grain?

Nick

That’s the thing. How do we work it out? And they took this kind of novel approach, which was to say, OK, well, let’s let’s not let’s let’s just look at the total dissolved solids. If we if we make everything else and even. Right. So use the same machine, you use the same coffee, you use the use the same amount of coffee that goes in to the basket, the same basket, everything else. Right.

Nick

So everything’s the same. And the only thing that will change and will same temperature and the only thing we’re going to change is nothing changes, nothing changes at all. And we’ll just see when we’ve got that amount of volume of coffee out. We’ll see what the total dissolvable solids are. Exactly. And so what that basically then refers back to what that means is if there’s a difference in the total dissolved solids, it means that there’s a difference in the grain size, the number of fines that are created.

Nick

OK, and they did it on, I think, three or four different grinders. And they and they did the Mahlkonig I don’t know the E43.

Nick

So basically the Mahlkolig,Mahlkolig E43, which is like suppose that is like the it’s not necessarily the best grinder in the world but but it’s right at the top of if you’re running a speciality coffee shop, that’s what you kind of generally want to have. You want to have one of those. So and and I can testify that they’re very good friend of mine had one. And I always wanted to steal it, but he was always he was always keeping a close eye on me whenever I was in the shop.

Nick

So so they had one of those and then they had, I think, three or four other different grinders. And I actually don’t really want to see the other ones because they didn’t do as well. But what they found was so typically an espresso. You’re looking at a as your ideal TDS is around I think 23 to 25 something like that. I had. Yeah, something like that. And what they found was that some grinders were coming in at 20 some that the Mahlkolig 43 was coming in at 23 point something, others were coming in at 20, some were coming in at 21, 22.

Nick

And they were then, then they were tasting them. Right. Then they were actually tasting the express. Is this crazy idea that actually if it tastes good and they indeed found that the higher the TDS given them everything else, the tastier it was and that the Mahlkolig came through all the the flavours came through. It was balanced, it had the sweetness, it had the acidity. It was fantastic. And it happened to have the highest TDS and so.

Nick

Ah and so what they’re referring back from that is, is that actually the production of of fines and the consistency in the production of, of grinds is, is, does vary from, from grind to grinder. Like it’s not like it’s a real thing. It’s not, it’s not a it’s not a market in terms on a marketing issue. So whatever technologies as grinding companies are using and people have different approaches, some of them are using the special treated burrs, some are using ceramic burrs.

Nick

Some of them are using heat management systems. As you pointed out, that only becomes an issue if you’re if you’re making coffee after coffee. And that is a big issue. And it’s not like an issue after the coffee. It’s an issue after the second coffee. Yes. And by the way, just to kind of like a rabbit hole, I always thought that that that there was a heat issue because it would affect the metal in the burrsand expand them.

Nick

And that’s what I’ve been telling people. And it turns out that that is so minimal that that hardly makes a difference. And actually, the problem is it expands the bean. The heat actually affects the beans and the beans can go up to one hundred degrees centigrade. Did you know that?

Max

I didn’t know that they got that high.

Nick

He can go. Apparently, they’ve measured it up to 100 degree centigrade, if you’re really smashing those beans through and the effect on the beans is that they expand and also the oils in the beans become less viscose. So what happens is they become less viscose and then they tend to coat stuff and then they then they later on, as it cools, they become more viscous and you get clumping. And so there’s a whole bunch of a whole bunch of impacts that that apparently happen from that from the heat on the beans.

Max

So clumping, I don’t agree totally with it, but I agree with the clumping into the into the the grinder. That does make sense.

Max

And on top of that, you should consider that a lot of these acids and fatty acids that you would then find in the cremaand. Yes. Yeah. And they are also forming agents. They are the surfactants. What you find in that case is that they might degrade because they are sometimes polyunsaturated or unsaturated fatty acids, which are 100 degrees. With within at high PH in contact with other stuff, they might react because you might encourage. You might encourage reactions and cross reactions between the different different things that are inside the coffee and the coffee bean.

Nick

I think I, I you’re absolutely right. I think I read something about that. So it actually we talk in coffee about gasification.

Max

So when you get it and I just remember one thing and oxygen, oxygen is everywhere. And the same way it makes your coffee beans go stale in your coffee grounds go stale, it would be even faster when you had temperature to heat.

Nick

That’s exactly what they said. Yeah. They said it will basically speed up the gasification process in the grinder, which will give you which will give you an inconsistent result as well.

Nick

So, hey, Max, do we miss anything with what we get at all? I don’t know. Probably not. I said welcome to part one of our one hundred part series. I think I was pretty good considering like I literally just written one line on my notes, which was inevitable, flat versus conical as far as I got before you jumped on the pool.

Max

I think that’s that’s good. We can talk about stuff I should never prepare. This is the one time to remember that one time I prepared and when I screwed it all up.

Nick

Yeah, yeah. This is the this is the lesson I’m going to pass down to my kids. Yeah. Never be prepared. Never be prepared. They’re all wrong, son.

Nick

Wing itt, your life. Go with it.

Nick

So anyway, who wins.

Who owns what? I don’t know, I don’t know. Is there no competition? We’re all a winner. Max, if you’ve ever gone to any school event recently in the last 10 years, you realize that there are no winners or losers. Although having said that. Oh, my God, I just realized. They are hypocrites because they called me out for cheating at an egg and spoon race. My kids at my kid’s school, but at the same the same day they were telling me that they weren’t awarding, that everybody was getting an award because because they said we don’t want them to be losers.

Nick

And I said, but life is full of losers. You know, if you don’t win, you lose. You got to got a bit of competitiveness. You know, that’s what you need. And they’re like, oh, no, no, we don’t want to you know, we don’t want to make children feel bad about, you know, losing or whatever.

Nick

And then they called me out. Your medals. Yeah, it was all such a bunch of rubbish. But then they caught me. I cheated on the egg and spoon race and then they actually, over a loudspeaker, disqualified me and my kids were very angry.

Nick

So. So we’re both winners, Max. That’s good. Yes. OK, so we got to talk next week, next week, there is a possibility that I’ll be on holiday and and we might skip a week on the podcast. But if that happens, be sure to tune into to hear nothing.

Max

Yes, we will also have and I know you don’t want to admit to this, but we will also have a review on decaf.

Nick

Oh, yeah. You know, we can do that. I really haven’t started yet because they’re still you have started it and I’m guessing it’s really good. You should try it. It’s really nice.

Nick

Well, you know, we got to we got two bags from that roast. Yes. And we got one with caffeinated and one that was one that was decaf. Almost caffeinated. Yeah. I’m finishing the caffeinated ones. Oh, no, sorry. I’m, I’m degassing. Another bag from something else. OK. Yeah. No, that’s just something, it’s a different thing I’m doing so. No you’re right. I’m drinking those. I’m drinking. You are.

Nick

I’m no I’m not. I’m doing the decaf. I’m drinking the caffeinated back first. And then I thought I would mix the decaffeinated with the other bag. I’ve got the other things because I can’t be doing without money. I don’t.

Max

Don’t. Try to decaf as it is. You’ll thank me. No, no, I mean, I’m not going to mix the decaf. I’m I’m going to have, like, one caffeinated coffee in the morning and then I’m going to have a decaf afterwards. But I’ve got to have caffeine. I get headaches. I’m a junkie.

Nick

What you mean I wonder if coffee junkie dotcom is taken of, you junkie. I’m pretty sure it whole. No, it’s for sale. Oh, hey, you just have to contact them and they’ll give you a price, all right? Yes, they’re definitely going to talk about we’re going to talk about decaf is going to be a big bold. I’m slightly nervous about it. I’m I’m worried that it’s going to be good enough.

Max

But if you like it, more like it.

Nick

What have you done to me? So we’re going to do that. So we do that. So we might do that next week. But if I’m go away, then then then we’ll do it the week after. Hey, Max, it’s been awesome, buddy. Thank you so much for your for your expertise on the grind. Don’t forget to send us in the detailed diagrams explaining everything that we talked about today.

Max

Yes, but to do that, though, I mentioned that the detailed diagram like it doesn’t need to be anything more than one hundred pages. That’s it is double sided, obviously, and obviously single spaced or things. Right. All right. I’ll see you maybe next week. Maybe. OK, yes. And by the way, we met in person. We met in person.

Nick

That’s right. I came round and when you went looking, I took your I took your coffee machine and run away with it the next.

Nick

Anyway, I was going to grab the gun, which you which you use subtlely but not so subtly, like booby trapped so that it would spray coffee in my face, as if it’s a bit like if Inspector Clouseau made coffee that was like me that day.

Oh, good. Anyway, see you next week.