In the pour-over section, the authors hit on a good point about height and creating a vortex in the slurry. Water temperature and flow rate are important variables too. Combined with the coffee grounds' quality (i.e. grind consistency) and whether it has fines or lots of chaff will also dictate how long it takes to draw down and therefore whether the pour height's effects will change if static.
I do like the advice grind coarser and extract with more water -- that's made my V60 coffee quality fairly consistent, but everyone's mileage will vary based on how they like their coffee and the roast profile.
There are so many other variables that didn't get a mention:
Coffee varietal
Water hardness (and even which other ions are present in the water) and its effects on acids and other compounds
that highlight certain varietal's defining characteristics.
Two of my nerdy passions are coffee and HiFi, and I've observed some degree of... let's call it "magical thinking" in both. Obsessing and over-exaggerating minute details of the process. The extremist audiophiles to a much more ludicrous and comical degree admittedly.
Brewing coffee and listening to music becomes much more of a ritual process, than a task grounded in reason, and the end result is unlikely to pass a double blind test.
"Let people enjoy things!"
Yes, yes. But if you're buying audiophile fuses or power cables, or you're using TDS meters, a 5000$ grinder or if your kettle has an app, in the words of one of the great thinkers of our time: it's time to stop.
Buy a reasonably priced burr grinder, an Aeropress or decent pour-over, and some nice quality coffee, and you will be drinking better coffee than 95% of people.
> The bottom line of the team’s experiments and mathematical modelling is that to get the most reproducible shots just use less coffee and grind it more coarsely.
This seems to go against conventional wisdom, which says that less coffee will reduce brewing time and a coarser grind will also reduce brewing time, and consensus seems to be that you want a brewing time somewhere between 20 and 30 seconds. Or did I misunderstand something?
Anyway, the reasoning seems sound, so I'm going to have to give this a try.
They suggest a courser size and less pressure to avoid channeling.
I’ve been using this technique for a while, I think the results are better (but of course there’s a strong bias when people think they are doing the cleverer thing in food preparation).
For light roasts I hold the pressure at around 1 bar for ~30 seconds before increasing to 7 or so.
They failed to mention the important point, that you have to be able to reduce the pressure to increase the grind size. I am convinced the best espresso you can make is at 6 bar, since you can grind the coarsest possible. It comes out sweeter and richer at the same time.
Some people go all the way down to 1 or 2 bars (soup espresso). I've mostly seen it in the context of very light roasts and I tend to buy darker roasts so I really haven't spent much time investigating it.
I did see a video on americano's recently where steaming the water to heat it rather than using a kettle or water from the espresso machine's boiler made a better drink. That does intrigue me and I'll probably give it a try this weekend.
Lately I've been making mostly decaf and it's really hard to get a good shot no matter what I try. Drip coffee comes out great, but my decaf espresso always seems to have a real harshness. Beans are fresh and my water is good, so I'm thinking it's time to replace the burrs in my grinder.
> steaming the water to heat it rather than using a kettle or water from the espresso machine's boiler made a better drink
Was it Mr Hoffmann[0]? He has a decent explanation for why this might be the case too (and does an experiment later which points to it maybe being dissolved gases.)
Well, pressure builds when the coffee bed restricts the flow of water. So if you don't have much restriction (really coarse grind) you're not going to build pressure :) so you don't have to actually change any settings to get a reduced pressure at the puck.
But I also do enjoy ~6bar shots using a traditional lever style machine.
You're spot on, but this coarser, faster-style shot is called the "turbo shot" and you don't actually have to use less coffee, you can actually use more - just compensate your grind to brew quickly. You will get more consistent results here, but they're very different from traditional espresso.
But, I think for any recipe, "total brew time" is just a way to communicate contact time with water, and should NOT be a goal unless you're trying to copy what someone else did with that same coffee, and is IMO more important for pour over in that regard than espresso.
Reproducible is necessary but not sufficient for consistently good coffee. If you can’t reproducible what you did, you aren’t able to make changes to improve over time.
This is why I think the Aiden is underrated. It way more consistent than I was when doing pour over but still lets me tweak variables.
Sorry, maybe I should have quoted the next line as well:
> Pabst echoes that advice: “My recommendation for people at home, without knowing anything they are doing, 90% chance that if you use less coffee and grind a little coarser [your coffee] will actually taste better.”
So it's not just about consistency, but also quality.
"taste better" does not mean quality either. What do I know about their tastes, they're scientists not baristas (in the article baristas were only asked about process options). Also they didn't discover anything new, just confirmed what everybody was telling them. And not at least, there are different methods of making coffee, while they smeared their espresso machine results interpretation over everything - like for instance to make Turkish coffee (aka pot) you must grind it the finest and use more.
Good is totally up to the person's tastes, anyway. Turbo style shots are the end-all-be-all for a lot of people who enjoy espresso. For other people, they hate it, for a multitude of reasons.
A pet peeve of mine is when people mention "weak" coffee. What does this mean?
The HTTP 418 I'm a teapot status response code indicates that the server refuses to brew coffee because it is, permanently, a teapot. A combined coffee/tea pot that is temporarily out of coffee should instead return 503.
I roast coffee professionally, and there's just a few things that will make up 98% of your coffee quality, and none of them have to do with technique. And without these no level of technique will ever compensate.
1) Sourcing high quality coffee to the roast level you enjoy. Try a lot of different coffees - from "Ultra Light" to "American Light" to "Medium" to "Dark" - and find what you enjoy, then find a roaster that produces those coffees to a high quality standard. There will not be a ton of these roasters in your country. Maybe even just a couple, even if you live in the US.
2) A good grinder, of course. Fortunately in the last few years this is wayyyy more accessible. There are pretty good options starting around $300, and the workflow isn't terrible for these picks, either. Of course the sky is the limit here, but it's really vital to a good cup.
3) Good water. You'll want to either find a bottled water brand you like for brewing, or use an reverse osmosis (can be a gravity type) system and remineralize it. Cafes do this (if they are any good) and you should too. There's a chance your tap is great for coffee, but only if you're pretty lucky.
4) Decent brewing equipment. The cheapest is a v60 for pour over. You can make good coffee with pretty much any machine, but some will get in your way and cause you to have to fuss with them much more.
Then, after those, is technique - and the most important part of technique is really grind size and water temperature (I suggest you do not go above 88c in most cases).
And here I am microwaving a cup of yesterday's brew of drip coffee that sat on the burner for two hours.
Same, but I appreciate when folks go deep into something they obviously care about
Had a good laugh! That could be me.
In the pour-over section, the authors hit on a good point about height and creating a vortex in the slurry. Water temperature and flow rate are important variables too. Combined with the coffee grounds' quality (i.e. grind consistency) and whether it has fines or lots of chaff will also dictate how long it takes to draw down and therefore whether the pour height's effects will change if static.
I do like the advice grind coarser and extract with more water -- that's made my V60 coffee quality fairly consistent, but everyone's mileage will vary based on how they like their coffee and the roast profile.
There are so many other variables that didn't get a mention: Coffee varietal
Water hardness (and even which other ions are present in the water) and its effects on acids and other compounds that highlight certain varietal's defining characteristics.
Vessel temperatures.
The filters used (materials, paper thinness).
Pouring patterns (circular, concentric, hypotrochoid, more?)
The filter shape and material.
Even the grinder used conical vs. flat burrs and high RPMs vs. low RPMs creates palpable flavor profile differences.
The rabbit hole goes deep and continues to expand.
Two of my nerdy passions are coffee and HiFi, and I've observed some degree of... let's call it "magical thinking" in both. Obsessing and over-exaggerating minute details of the process. The extremist audiophiles to a much more ludicrous and comical degree admittedly.
Brewing coffee and listening to music becomes much more of a ritual process, than a task grounded in reason, and the end result is unlikely to pass a double blind test.
"Let people enjoy things!"
Yes, yes. But if you're buying audiophile fuses or power cables, or you're using TDS meters, a 5000$ grinder or if your kettle has an app, in the words of one of the great thinkers of our time: it's time to stop.
Buy a reasonably priced burr grinder, an Aeropress or decent pour-over, and some nice quality coffee, and you will be drinking better coffee than 95% of people.
> The bottom line of the team’s experiments and mathematical modelling is that to get the most reproducible shots just use less coffee and grind it more coarsely.
This seems to go against conventional wisdom, which says that less coffee will reduce brewing time and a coarser grind will also reduce brewing time, and consensus seems to be that you want a brewing time somewhere between 20 and 30 seconds. Or did I misunderstand something?
Anyway, the reasoning seems sound, so I'm going to have to give this a try.
These was actually a sort of fun and popular research paper about this,
https://www.cell.com/matter/fulltext/S2590-2385(19)30410-2
They suggest a courser size and less pressure to avoid channeling.
I’ve been using this technique for a while, I think the results are better (but of course there’s a strong bias when people think they are doing the cleverer thing in food preparation).
For light roasts I hold the pressure at around 1 bar for ~30 seconds before increasing to 7 or so.
Ah, too bad my machine doesn't let me set the pressure
They failed to mention the important point, that you have to be able to reduce the pressure to increase the grind size. I am convinced the best espresso you can make is at 6 bar, since you can grind the coarsest possible. It comes out sweeter and richer at the same time.
Some people go all the way down to 1 or 2 bars (soup espresso). I've mostly seen it in the context of very light roasts and I tend to buy darker roasts so I really haven't spent much time investigating it.
I did see a video on americano's recently where steaming the water to heat it rather than using a kettle or water from the espresso machine's boiler made a better drink. That does intrigue me and I'll probably give it a try this weekend.
Lately I've been making mostly decaf and it's really hard to get a good shot no matter what I try. Drip coffee comes out great, but my decaf espresso always seems to have a real harshness. Beans are fresh and my water is good, so I'm thinking it's time to replace the burrs in my grinder.
> steaming the water to heat it rather than using a kettle or water from the espresso machine's boiler made a better drink
Was it Mr Hoffmann[0]? He has a decent explanation for why this might be the case too (and does an experiment later which points to it maybe being dissolved gases.)
[0] https://www.youtube.com/watch?v=0HdzJz_evNw
Well, pressure builds when the coffee bed restricts the flow of water. So if you don't have much restriction (really coarse grind) you're not going to build pressure :) so you don't have to actually change any settings to get a reduced pressure at the puck.
But I also do enjoy ~6bar shots using a traditional lever style machine.
You're spot on, but this coarser, faster-style shot is called the "turbo shot" and you don't actually have to use less coffee, you can actually use more - just compensate your grind to brew quickly. You will get more consistent results here, but they're very different from traditional espresso.
But, I think for any recipe, "total brew time" is just a way to communicate contact time with water, and should NOT be a goal unless you're trying to copy what someone else did with that same coffee, and is IMO more important for pour over in that regard than espresso.
Reproducibility doesn't mean good.
I can make bad coffee every time myself by putting 2 spoons of vinegar in it.
Yeah.
"most reproducible" -> Does not mean good.
A lot of generic weak coffee is 'consistent', but not 'good'.
Reproducible is necessary but not sufficient for consistently good coffee. If you can’t reproducible what you did, you aren’t able to make changes to improve over time.
This is why I think the Aiden is underrated. It way more consistent than I was when doing pour over but still lets me tweak variables.
Sorry, maybe I should have quoted the next line as well:
> Pabst echoes that advice: “My recommendation for people at home, without knowing anything they are doing, 90% chance that if you use less coffee and grind a little coarser [your coffee] will actually taste better.”
So it's not just about consistency, but also quality.
"taste better" does not mean quality either. What do I know about their tastes, they're scientists not baristas (in the article baristas were only asked about process options). Also they didn't discover anything new, just confirmed what everybody was telling them. And not at least, there are different methods of making coffee, while they smeared their espresso machine results interpretation over everything - like for instance to make Turkish coffee (aka pot) you must grind it the finest and use more.
Good is totally up to the person's tastes, anyway. Turbo style shots are the end-all-be-all for a lot of people who enjoy espresso. For other people, they hate it, for a multitude of reasons.
A pet peeve of mine is when people mention "weak" coffee. What does this mean?
The HTTP 418 I'm a teapot status response code indicates that the server refuses to brew coffee because it is, permanently, a teapot. A combined coffee/tea pot that is temporarily out of coffee should instead return 503.
I roast coffee professionally, and there's just a few things that will make up 98% of your coffee quality, and none of them have to do with technique. And without these no level of technique will ever compensate.
1) Sourcing high quality coffee to the roast level you enjoy. Try a lot of different coffees - from "Ultra Light" to "American Light" to "Medium" to "Dark" - and find what you enjoy, then find a roaster that produces those coffees to a high quality standard. There will not be a ton of these roasters in your country. Maybe even just a couple, even if you live in the US.
2) A good grinder, of course. Fortunately in the last few years this is wayyyy more accessible. There are pretty good options starting around $300, and the workflow isn't terrible for these picks, either. Of course the sky is the limit here, but it's really vital to a good cup.
3) Good water. You'll want to either find a bottled water brand you like for brewing, or use an reverse osmosis (can be a gravity type) system and remineralize it. Cafes do this (if they are any good) and you should too. There's a chance your tap is great for coffee, but only if you're pretty lucky.
4) Decent brewing equipment. The cheapest is a v60 for pour over. You can make good coffee with pretty much any machine, but some will get in your way and cause you to have to fuss with them much more.
Then, after those, is technique - and the most important part of technique is really grind size and water temperature (I suggest you do not go above 88c in most cases).
For an entire book about the topic, see "The physics of filter coffee" by Jonathan Gagné.
Also
> This can be achieved using an espresso machine (figure 1), or with smaller contraptions at much lower pressures such as a moka pot or AeroPress.
Please, just stop. They're not even remotely close.
> "It takes more than 150 people to make a cup of coffee, from farmer to barista."
I do not, nor have I ever, utilized the services of a barista. I make coffee at home or I purchase it from Wawa, Sheetz, 7-Eleven, whatnot.