5 ms·

Systematically Improving Espresso (2020) [pdf]

43 points by Gatsky 4y ago

Gatsky 4y ago
Also here: https://www.theage.com.au/national/international-scientific-study-says-your-barista-is-making-your-coffee-all-wrong-20200122-p53trn.html https://www.theage.com.au/national/international-scientific-...
- esperent 4y ago
  Not impressed by that article, it's sensationalist and fairly uninformed. Not terrible either, it's just typical newspaper science reporting. Sounds good until they write about a subject that you know about and then you realize it's actually pretty bad. > Espresso is always – always – extracted with a water pressure between 9 and 10 bars. No, it's not. Especially amongst enthusiasts experimenting with pressure is extremely common. Although it is true that many machines are locked to 9 bars, it's also true that most cheaper home machines are set to 11/12 bars, and high end machines are starting to allow you to customize the pressure, even changing it throughout a shot. It's my experience that most espresso folk would say anything from 6-12 bars is an espresso, although going over 9 is usually frowned on.
hardwaregeek 4y ago
James Hoffmann has a video on this paper: https://www.youtube.com/watch?v=BoYBLn9hRqs https://www.youtube.com/watch?v=BoYBLn9hRqs In my view, sure it's a perfectly good way of making something like espresso with good extraction, what a lot of coffee people call these days a turboshot. But it's not really providing what people usually want in an espresso: a concentrated, textured small coffee.
- LesZedCB 4y ago
  Lance Hedrick has a little more in-depth video, I found James' to be too brief. https://www.youtube.com/watch?v=kOSbOZY_tN0 https://www.youtube.com/watch?v=kOSbOZY_tN0 i definitely don't drink a lot of dark roast espresso, but i think a turboshot has no problem producing adequate texture.
  - lostlogin 4y ago
    But is it espresso? If you take a purist definition (9-10 bar extraction pressure) then some of the papers testing falls outside the definition. If it tastes different and is made in a new way, shouldn’t it get its own name?
    - esperent 4y ago
      Basically no one outside of Italy (where the definition was created) takes a purist approach to espresso anymore. Certainly no one in barista competitions ever uses it for the last 20 years or so. I can't recall the exact official definition but it's something like: 7g of coffee extracted under 9 bars of pressure at 94C yielding 14g of liquid. It's extremely limiting, for example it's designed for dark roast and isn't ideal for medium/light specialty coffee where you might have to adjust the temperature and yield to get good results. Modern high end espresso machines these days are starting to allow you to play with the variables and in the espresso community it's usually considered that anything over 6 bars is an espresso. Also, other techniques like pre-infusing at 1-3 bars before ramping up the pressure is common. Personally I'm partial to a long 20s pre-infusion at 1 bar before ramping up to 6-7bars. This yields a very sweet shot with a medium roast bean.
      - lostlogin 4y ago
        Oh for sure, I’m more arguing that it deserves a better name because as you note, it’s outside the normal for an espresso. Pre infusion aside, the article starts at the low end of your definition but does have graphs that go as low as 4 bar. That’s almost at the stage of being made using the pre infusion only, and perhaps I should try that as that’s down there. I prefer a thick crema (for look and taste) but I’ll try drop the pressure down and see if I’m persuaded. Regarding your long pre infusion - how much of the shot is being extracted after 20 seconds? I’d expect a good 5-10ml by that time but maybe your pressure is so low that little comes out.
        esperent 4y ago
        > how much of the shot is being extracted after 20 seconds? Basically zero, maybe one or two drops. You need to grind finer though and you need a grinder capable of that. A decent hand grinder is ok (e.g. 1zpresso jx pro or max) but for electric grinders you're into the $600+ range before you can do it, e.g. a specialita or a niche .
CTDOCodebases 4y ago
It all comes down to the roast profile and the personal preference of the person drinking the coffee. Before the Nordic Countries influenced the roasting style of espresso an overdosed and under extracted espresso was palatable. After the influence a cup brewed like this was incredibly acidic. Like reflux in a cup.
- lostlogin 4y ago
  Over dosed and over tamped, the thicker the shot the better. Then a splash of milk to take off the bitter edge. Others can disagree but that’s my beverage. It’s also not an espresso, and is probably a macchiato. Are Nordic countries to blame for this style? Naples in particular but Italy and also France are known for a pretty acid coffee.
  - CTDOCodebases 4y ago
    In the specialty coffee scene I would say so. I think Tim Wendelboe influenced a lot of roasters within that part of the industry all around the world. Specialty coffee isn't just a buzzword too although it is often used as one. It specifically refers to green (raw) coffee rated 80-100 by a qualified grader. When you are paying good money for a quality coffee it doesn't make much sense to roast out the individual characteristics of the coffee i.e you either roast off the acidity and the aromatics or you keep the aromatics but accept higher levels of acidity. I travelled to Italy and France before I got into specialty coffee. At the time the style of coffee in Italy at best was a nice simple chocolate/caramel/toffee cup. Not overly acidic at all. All the coffees I had in France were terrible. The best way to describe them would be ashtray/bitter. I know in later years people from the Australian scene moved to (or back to) Paris and opened shops importing specialty coffee from other European countries or just started roasting their own. To be fair thought you can't talk about coffee without taking price into consideration. Quality varies wildly too within a given market even though price may stay the same. A few anecdotal experiences in different cities can have you comparing the equivalent of a loaf of bread purchased at the supermarket to a loaf of bread baked by an artisan.
    - 4y ago
almostarockstar 4y ago
Off-topic, but that paper is extremely well formatted and illustrated. It was a true pleasure to scan through.
nullbyte808 4y ago
"As we demonstrated in Figure 3, our model informs us that a reduction in dry coffee mass results in an increased EYmax (shown schematically in blue in Figure 6). Thus, a barista is able to achieve highly reproducible espresso with the same EY as the 20 g espresso by reducing the coffee mass to 15 g and counter-intuitively grinding much coarser (as shown in red, Figure 6B). This modification may result in very fast shots (<15 s), a reduction in espresso concentration, and a different flavor profile."
- lostlogin 4y ago
  It really doesn’t sound like an appealing shot. It sounds watery and weak.
  - esperent 4y ago
    The claim in the paper is that extraction efficiency goes up so it should roughly as strong as a normal espresso but using less coffee. I haven't tried it yet myself so no idea if that's true or not. However my expectation is that it's probably fine, just with a bit less complexity of flavor and no crema. We can argue about whether crema is a good thing or not but I can say for sure that if you serve espresso without crema in a cafe, you'll get complaints, no matter how good it tastes. Appearance matters.
    - lostlogin 4y ago
      That’s a good observation. I’d be unhappy if there was no crema if I was paying and while I wouldn’t complain, I’d remake any shot that didn’t contain it if making my own. But as you say, it may be a visual thing. A shot made from robusta looks amazing. The taste is often (but not always) harsh at best.
menaerus 4y ago
As a person with technical background, I found espresso brewing process really fascinating and I always thought that it could be expressed through a set of non-trivial mathematical equations and now there it is - it's all in this paper :D
pif 4y ago
Warning: no author is Italian. Which means that nobody knows what they are talking about. ;-)

43 points by Gatsky 4y ago

Also here: https://www.theage.com.au/national/international-scientific-study-says-your-barista-is-making-your-coffee-all-wrong-20200122-p53trn.html https://www.theage.com.au/national/international-scientific-...

esperent 4y ago
Not impressed by that article, it's sensationalist and fairly uninformed. Not terrible either, it's just typical newspaper science reporting. Sounds good until they write about a subject that you know about and then you realize it's actually pretty bad. > Espresso is always – always – extracted with a water pressure between 9 and 10 bars. No, it's not. Especially amongst enthusiasts experimenting with pressure is extremely common. Although it is true that many machines are locked to 9 bars, it's also true that most cheaper home machines are set to 11/12 bars, and high end machines are starting to allow you to customize the pressure, even changing it throughout a shot. It's my experience that most espresso folk would say anything from 6-12 bars is an espresso, although going over 9 is usually frowned on.

hardwaregeek 4y ago

James Hoffmann has a video on this paper: https://www.youtube.com/watch?v=BoYBLn9hRqs https://www.youtube.com/watch?v=BoYBLn9hRqs In my view, sure it's a perfectly good way of making something like espresso with good extraction, what a lot of coffee people call these days a turboshot. But it's not really providing what people usually want in an espresso: a concentrated, textured small coffee.

LesZedCB 4y ago
Lance Hedrick has a little more in-depth video, I found James' to be too brief. https://www.youtube.com/watch?v=kOSbOZY_tN0 https://www.youtube.com/watch?v=kOSbOZY_tN0 i definitely don't drink a lot of dark roast espresso, but i think a turboshot has no problem producing adequate texture.
- lostlogin 4y ago
  But is it espresso? If you take a purist definition (9-10 bar extraction pressure) then some of the papers testing falls outside the definition. If it tastes different and is made in a new way, shouldn’t it get its own name?
  - esperent 4y ago
    Basically no one outside of Italy (where the definition was created) takes a purist approach to espresso anymore. Certainly no one in barista competitions ever uses it for the last 20 years or so. I can't recall the exact official definition but it's something like: 7g of coffee extracted under 9 bars of pressure at 94C yielding 14g of liquid. It's extremely limiting, for example it's designed for dark roast and isn't ideal for medium/light specialty coffee where you might have to adjust the temperature and yield to get good results. Modern high end espresso machines these days are starting to allow you to play with the variables and in the espresso community it's usually considered that anything over 6 bars is an espresso. Also, other techniques like pre-infusing at 1-3 bars before ramping up the pressure is common. Personally I'm partial to a long 20s pre-infusion at 1 bar before ramping up to 6-7bars. This yields a very sweet shot with a medium roast bean.
    - lostlogin 4y ago
      Oh for sure, I’m more arguing that it deserves a better name because as you note, it’s outside the normal for an espresso. Pre infusion aside, the article starts at the low end of your definition but does have graphs that go as low as 4 bar. That’s almost at the stage of being made using the pre infusion only, and perhaps I should try that as that’s down there. I prefer a thick crema (for look and taste) but I’ll try drop the pressure down and see if I’m persuaded. Regarding your long pre infusion - how much of the shot is being extracted after 20 seconds? I’d expect a good 5-10ml by that time but maybe your pressure is so low that little comes out.
      - esperent 4y ago
        > how much of the shot is being extracted after 20 seconds? Basically zero, maybe one or two drops. You need to grind finer though and you need a grinder capable of that. A decent hand grinder is ok (e.g. 1zpresso jx pro or max) but for electric grinders you're into the $600+ range before you can do it, e.g. a specialita or a niche .

CTDOCodebases 4y ago

It all comes down to the roast profile and the personal preference of the person drinking the coffee. Before the Nordic Countries influenced the roasting style of espresso an overdosed and under extracted espresso was palatable. After the influence a cup brewed like this was incredibly acidic. Like reflux in a cup.

lostlogin 4y ago
Over dosed and over tamped, the thicker the shot the better. Then a splash of milk to take off the bitter edge. Others can disagree but that’s my beverage. It’s also not an espresso, and is probably a macchiato. Are Nordic countries to blame for this style? Naples in particular but Italy and also France are known for a pretty acid coffee.
- CTDOCodebases 4y ago
  In the specialty coffee scene I would say so. I think Tim Wendelboe influenced a lot of roasters within that part of the industry all around the world. Specialty coffee isn't just a buzzword too although it is often used as one. It specifically refers to green (raw) coffee rated 80-100 by a qualified grader. When you are paying good money for a quality coffee it doesn't make much sense to roast out the individual characteristics of the coffee i.e you either roast off the acidity and the aromatics or you keep the aromatics but accept higher levels of acidity. I travelled to Italy and France before I got into specialty coffee. At the time the style of coffee in Italy at best was a nice simple chocolate/caramel/toffee cup. Not overly acidic at all. All the coffees I had in France were terrible. The best way to describe them would be ashtray/bitter. I know in later years people from the Australian scene moved to (or back to) Paris and opened shops importing specialty coffee from other European countries or just started roasting their own. To be fair thought you can't talk about coffee without taking price into consideration. Quality varies wildly too within a given market even though price may stay the same. A few anecdotal experiences in different cities can have you comparing the equivalent of a loaf of bread purchased at the supermarket to a loaf of bread baked by an artisan.
  - 4y ago

almostarockstar 4y ago

Off-topic, but that paper is extremely well formatted and illustrated. It was a true pleasure to scan through.

nullbyte808 4y ago

"As we demonstrated in Figure 3, our model informs us that a reduction in dry coffee mass results in an increased EYmax (shown schematically in blue in Figure 6). Thus, a barista is able to achieve highly reproducible espresso with the same EY as the 20 g espresso by reducing the coffee mass to 15 g and counter-intuitively grinding much coarser (as shown in red, Figure 6B). This modification may result in very fast shots (<15 s), a reduction in espresso concentration, and a different flavor profile."

lostlogin 4y ago
It really doesn’t sound like an appealing shot. It sounds watery and weak.
- esperent 4y ago
  The claim in the paper is that extraction efficiency goes up so it should roughly as strong as a normal espresso but using less coffee. I haven't tried it yet myself so no idea if that's true or not. However my expectation is that it's probably fine, just with a bit less complexity of flavor and no crema. We can argue about whether crema is a good thing or not but I can say for sure that if you serve espresso without crema in a cafe, you'll get complaints, no matter how good it tastes. Appearance matters.
  - lostlogin 4y ago
    That’s a good observation. I’d be unhappy if there was no crema if I was paying and while I wouldn’t complain, I’d remake any shot that didn’t contain it if making my own. But as you say, it may be a visual thing. A shot made from robusta looks amazing. The taste is often (but not always) harsh at best.

menaerus 4y ago

As a person with technical background, I found espresso brewing process really fascinating and I always thought that it could be expressed through a set of non-trivial mathematical equations and now there it is - it's all in this paper :D

pif 4y ago

Warning: no author is Italian. Which means that nobody knows what they are talking about. ;-)