Coffee with a splash of physics: how to make the most out of your brew
Comments
zahma
Broken_Hippo
Even the grinder used conical vs. flat burrs and high RPMs vs. low RPMs creates palpable flavor profile differences
I bought a good grinder about 6 months ago - a Fellow. I changed nothing other than the grinder and my coffee improved. And it is so much more enjoyable to use: Less mess and static, less noise, and everything feels nice to use.
zikduruqe
No doubt. I found a Fellow Ode cheap, and upgraded to the Gen 2 burrs. My coffee went from a little better than 2 am truck stop coffee, to something better than you can get at a cafe.
I am using a Breville precision brewer, but would love to upgrade to a Moccamaster one day.
rkomorn
I've somewhat recently found out that I enjoy hand grinding beans and having the resulting coffee quite a bit.
There's something about the sound, the smell, and the feeling once the last bean is ground, that just works for me.
Maybe some years ago I'd have chastised my future self for enjoying something I certainly couldn't identify in a blind test, but nowadays I'm all for "whatever works."
registeredcorn
I'm not a high-end coffee drinker so I hadn't heard of that company before. I took a look at their site and was toying with the idea of trying one of their cheaper products but it looks like the French Press has serious build quality issues with the handle snapping off.
Have you noticed any kind of issues in term of build quality of their products?
amarant
Knowing how cool and nerdy coffee enthusiasts can get, do you know if any studies that support the rpm grinding difference in flavour?
I know a coffee grower who put his beans through a spectrometer to determine whether sun drying his beans actually altered the flavour profile compared to machine drying. He wanted to eliminate placebo mostly I think. He could demonstrate a clear difference in the spectrometer between sun dried and machine dried beans, with both batches of beans coming from the same field, the same year.
I just love how nerdy coffee nerds are!
AnthonBerg
I propose a mechanism that brings about the difference:
Higher speed cracks the brittle beans differently, smashing them into a higher proportion of fines.
Fine and coarse particles yield very different proportions of compounds into the water – the less soluble stuff kind of only washes off the surface of the ground particles. Finer particles, more surface, more of the hard-to-extract less soluble stuff.
encom
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.
seemaze
I recently replied to a thread about La Marzocco espresso machines[0] regarding the value proposition of expensive coffee gear. I think the mistake in magical thinking is the attempt to rationalize the high cost through a comparative cost benefit analysis with retail (non-commercial) competition.
"I just overhauled a la marzocco sitting in my kitchen. People often inquire about whether it's worth buying an espresso machine for the home, or if it's a good investment as a coffee connoisseur.
My reply is always that it was the best money I've ever spent and the worst investment I've ever made. It's a lifestyle choice, and a questionable one at that. But one I'd make again every time given the opportunity."
fabian2k
There's certainly people that focus too much on minor details. And you really don't need to go into the 4-digit in spending to get very good coffee (especially if you don't want Espresso). But I was a bit surprised how much small details can matter in brewing coffee.
I'm using an Aeropress and an 1ZPresso handgrinder. I found that it helped a lot to do things exactly the same way each time. It reduced variability and made it easier to adjust a parameter like grind size. In particular I found stirring to be a really finicky parameter with a potentially large effect. If I stirred vigorously without changing anything else, the coffee got noticeably bitter. I switched to not stirring at all, it's mixed plenty just by pouring the water. Makes the workflow easier and reduces variability.
So while I think there's plenty of ritual around coffee that has no real effect, I suspect the value lies in keeping to exactly the same method and performing all steps the same way each time.
Slow_Hand
Reading the discussion in these comments I have the exact same thought about parallels with hi-fi enthusiasts. Then I saw your comment. 100% agree.
The person I really want to hear from about brewing coffee is a chef. Someone who probably doesn't have the time to nerd-out to this degree, has great taste, sees the big picture and is likely to have settled on the most practical balance between quality and diminishing returns.
Theodores
It is time to stop!!!
...and I stopped. I didn't get to the $5000 grinder stage, but the annual costs of coffee were alarming. I went for black tea instead, served in insulated mugs and flasks. Originally the plan was to just have coffee as a treat when meeting friends in coffee serving establishments, however, that doesn't happen. I buy coffee for whomever I am with and keep my flask below the table, still spending, but not consuming.
For all the thousands of coffee cups had, I can't think of any contenders for the 'greatest one'. Hence, despite the rituals and expense, it was all forgettable. Yet I was so insistent on getting my fix.
After some time away, I can see coffee for what it is. There are too many children in the south doing things with coffee beans for grown adults in the north. Shouldn't they be in school? Tea isn't quite the same, picking leaves is different, even though I haven't done it myself, there are worse jobs to have.
The paraphernalia aspect is also something I now reject. Fancy coffee machines and even the Aeropress just says 'it's time to stop'.
Similarly, the elevation of the job of 'coffee maker' to the grand role of 'barista' irks me. We place the 'barista' up there with the greatest composers, rocket surgeons and rock gods. Sure, a 'barista' might be your greatest ever hero if all you do is drink coffee and the only work in your country is in customer service, but I don't see the 'barista' job as worthy of a pedestal, particularly in countries where the pay comes primarily from tips.
Then there is everything else, the take-out cup, the animal excretions, the added sugar. My comfort drink of old, a frothy latte in a plastic lined paper cup, is not what my body really needed. You have got the stimulant from the caffeine, and you don't need stimulants if you get all your nutrients. The mix of milk and sugar would be considered wrong by a true coffee drinker, regardless, you have got diabetes in a cup right there, with saturated fats and 'free' sugars. You are just asking for arteries to be blocked and for dementia to happen.
Whether aware of it or not, there is status with beverages. We all want to eat from the king's table, not the animal's stable. I can't say I impressed anyone with coffee, whether making it or drinking it. One lesson learned, make coffee for people and it just becomes expected. Being a keen coffee drinker doesn't make you cool. I am not saying that drinking just black tea makes one cool, but, for people that are coffee dependent, with other beverages consumed, the idea of drinking just tea, with no additives, is crazy talk.
Each to their own, but I am seeing so many upsides to 'tea only' that I see no reason to change, apart from tannin on teeth, which can be a problem if also consuming lots of colourful spices. The money aspect is an invisible upside, it is not like I get a lump sum for all that money saved, even though it is thousands a year. The lack of waste is definitely really good, since I don't have glass jars, single use cups, plastic milk cartons and more coffee-related trash to dispose off. Tea is actually valuable in the second life for composting reasons.
Anyway, having been away from coffee for quite a few years, I still appreciate the smell, but I am not tempted. To me the obsession with coffee is amusing, much like seeing what some cats will do with catnip, it just seems a bit unnecessary. My taste buds have adapted, I moved on.
poloniculmov
There's forced labour and child labour in tea growing, it's mostly grown in countries that have different definitions for human rights. And unless you're buying specialty tea, those farmers are paid pennies while doing hard work.
I don't think there's any ethical consumption of industrial scale agriculture that cannot be mechanized, because we don't want to pay the real costs.
cf100clunk
SURGEON GENERAL'S WARNING: Caffeine withdrawal can cause chronic, acute migraine headaches.
Satire of such package labels, but unfortunately true for some coffee devotees.
snarfy
And here I am microwaving a cup of yesterday's brew of drip coffee that sat on the burner for two hours.
derwiki
Same, but I appreciate when folks go deep into something they obviously care about
raffael_de
If that's what somebody cares about, it might be time to question what is worth caring about.
cf100clunk
A friend does that too, but then adds evaporated milk.
gond
Had a good laugh! That could be me.
mr_mitm
> 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.
bee_rider
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.
mr_mitm
Ah, too bad my machine doesn't let me set the pressure
bee_rider
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sgc
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.
criddell
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.
sgc
1-2 bars isn't really espresso, it's a moka - which can be quite good in its own right. It falls into the genus of pressurized brewing though, so same genus different species. There's a no man's land from 3-5 bars that is not really used and might be worth exploring, but most 'standards' consider 6 bar the minimum to be a true espresso.
criddell
The SCAA (Specialty Coffee Association of America) has an even more restrictive definition[1]:
> Espresso is a 25–35ml (.85–1.2 ounce [×2 for double]) beverage prepared from 7–9 grams (14–18 grams for a double) of coffee through which clean water of 195°–205°F (90.5°–96.1°C) has been forced at 9–10 atmospheres of pressure, and where the grind of the coffee is such that the brew time is 20–30 seconds. While brewing, the flow of espresso will appear to have the viscosity of warm honey and the resulting beverage will exhibit a thick, dark golden crema.
I have no problem with calling soup espresso. It's ground coffee brewed under pressure in an espresso machine and that's good enough for me.
[1]:https://sca.coffee/sca-news/25-magazine/issue-3/defining-eve...
sgc
Of all the standards, I find the SCAA the least useful. That was the standard 30 years ago, but nobody serious about improving their craft is brewing such a watered down espresso anymore, and a 1:2 ratio is the most common one. So 15g for 30ml. And for pressure, modern consensus is that 9 bar is the high upper limit. 10 almost always leads to a harsh cup. I find the 6 bar lower limit to be a tipping point in the concentration, such that lower pressures are more similar to drip than to espresso - the viscosity and mouthfeel changes dramatically. So I can't agree that whatever comes out of an espresso machine should be called espresso. But we are debating vernacular here, I just hope you enjoy your cup of coffee!
zimpenfish
> 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.)
criddell
Yes, that's the video. He doesn't seem to be a fan of americanos. It's one of my favorites so I'm pretty interested in new ideas for one of the most basic drinks.
roflyear
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.
sgc
Yes of course, but by dropping opv pressure on most home machines that also drops flow due to opv bleed off. If you have your opv at 9-10 bar you get a full flow shot on a coarser grind - which is way too fast. You need to drop pressure until you can keep your wet time the same (I use the pretty standard 17g coffee 34 ml out, 34 seconds wet, upped to 40 seconds because I use preinfusion). If you have a fancier machine you can just adjust flow directly, but then you can set pressure directly so why wouldn't you do that too.
BiteCode_dev
Reproducibility doesn't mean good.
I can make bad coffee every time myself by putting 2 spoons of vinegar in it.
roflyear
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.
FrustratedMonky
Yeah.
"most reproducible" -> Does not mean good.
A lot of generic weak coffee is 'consistent', but not 'good'.
mr_mitm
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.
soco
"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.
canes123456
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.
roflyear
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?
urxvtcd
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.
roflyear
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).
BashiBazouk
Slathering it on a bit thick there?
The importance of technique was demonstrated to me over half a century ago. I grew up in Santa Cruz which has the Santa Cruz Coffee Roasting Company. They have been doing the pour overs since the early 80's. They have two cafes. A sit down large cafe and about four blocks away an annex in the bus depot (no longer there). The annex was basically a small room with a coffee bar. Both the main cafe and the annex did the pour over with the same coffee, same bad city water (probably filtered), same kind of grinder and same coffee bar pour over setup. The only difference was the cafe was large and the employee pouring would walk off and do other job related tasks. In the annex the person pouring was trapped and therefore much more attentive to the pour. The annex had consistently vastly better coffee.
As to "Maybe even just a couple, even if you live in the US.". I now live in Portland with 48 independent roasters. They all suck? I wonder how they would rate your coffee roasting. Yes, slathered on a bit thick.
I love coffee because the good stuff is really good. The decent stuff is still pretty good and the bad stuff is passable when you really need it.
cf100clunk
> There's a chance your tap is great for coffee, but only if you're pretty lucky.
I've worked and RV'ed throughout the USA and Canada. Canadian urban areas tend to have good quality tap water for coffee making. Canadians know that in only a few seconds the water will run truly cold. The USA's tap water as one gets further south from the Canadian border has generally dreadful taste and temperature, meaning chilled, bottled water is a necessity.
hermitcrab
>A good grinder, of course.
I recently switched my ancient ~£50 grinder for a ~£250 grinder and the change in the quality of the espressos is very noticeable.
sbolt
Who are the US roasters you like?
Eisenstein
What is a gravity type reverse osmosis system?
aboardRat4
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.
soopypoos
I pity the fool who's never sucked coffee from a teapot
cindyllm
[dead]
deckar01
There is another solution: Get a machine with flow control and a pressure gauge on the group head. You can saturate the puck at low pressure to avoid dry pockets, then ramp the flow rate up until the group head pressure peaks. If the pressure starts to drop you can increase the flow to maintain the group head pressure.
As for the 6 bar course grind theory: You may maximize the extraction of soluble coffee mass, but the concentration will be lower. It does not take very much extra water to ruin the taste and texture of a latte.
metalman
couple of relevant things
tone is in the hands.
and if you dont know or instantly understand what various foods sound like when things are going right, stay out of the kitchen.
my life has been blessed by some world class mentors, and when I watch a true master, say, barista at work, operating with a focus and good cheer, idistinguishable from a ferocious beast in there lair, then yes, I stand down, simplicate MY process and have another go, which has in fact resulted in my ability to make a consistent brew that I am very happy with.
take your pedals, and other gadjets down to the curb, and work with an absolute minimum till it starts to click.
NoSalt
> "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.
NoSalt
Ah, I see by the down-votes to my personal position, that I have been met with immigrants from Reddit.
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.