4 ms·

> Habitual coffee consumption ranges from about 1 to more than 5 cups per day, which indicates that the daily dose is defined by something other than genetic re

> Habitual coffee consumption ranges from about 1 to more than 5 cups per day, which indicates that the daily dose is defined by something other than genetic reasons. One curious question I've always struggled with is, what is a "true" cup of coffee? I've often seen people say a "coffee" cup is 6 oz, but then I'm confused by this: 1 US cup = 8 oz 1 Imperial (British) = 10 oz 1 Australian cup = 8.45 oz

hprotagonist 6y ago
“coffee cup” is a semi-standard unit just like the ones you listed are. And yes, it’s about 6 fluid ounces, and no, nobody in the real world means “i drank 6 fluid ounces of coffee” when they say “i had a cup of coffee”. Overloading is fun!
- varnisher 6y ago
  Instead of measuring coffee you could measure caffeine content, but a lot of effects may be in non-caffeine ingredients. Still, it's a first step.
  - lowmemcpu 6y ago
    That's what led me down this path. Searching the internet for "how much caffeine is in a cup of coffee" leads to the question of "what is a cup?", "how did you brew it?", "what kind of grounds did you use?".
    - hprotagonist 6y ago
      the real world is very nonlinear.
  - hprotagonist 6y ago
    “total dissolved solids” is a more comprehensive measure of coffee strength for the entourage effects reason.
jcims 6y ago
I think the cup count is useful from the habit standpoint, but the study should probably also include style of coffee or caffeine content. If I drink brewed coffee I’m on a steady flow for the day, sometimes making a second pot in the afternoon. I bought an espresso machine about a year ago, and one Americano in the morning pretty much sets me up for the whole day.
dcolkitt 6y ago
I've been confused by this for a while as well. The answer seems to be there's not such thing as a "true" cup of coffee. It pretty much just means whatever the respondent considers a cup. (In contrast to studies on alcohol consumption, where researchers have standardized units. And even on surveys will make sure to clarify with respondents so they get responses in normalized units.)
- jschwartzi 6y ago
  There's an ISO standard for how to brew tea for laboratory comparison: https://en.wikipedia.org/wiki/ISO_3103 https://en.wikipedia.org/wiki/ISO_3103 Also here are all the ISO standards for coffee: https://www.iso.org/committee/47950/x/catalogue/p/1/u/0/w/0/d/0 https://www.iso.org/committee/47950/x/catalogue/p/1/u/0/w/0/... They don't yet have any brewing standards but a lot of what they seem to do is by nose with green or roasted ground coffee.
paulcole 6y ago
Many commercial coffee makers use 5 ounces when calculating the number of cups they serve. Scroll down to the comparison chart and look at the carafe sizes: https://www.bedbathandbeyond.com/store/product/ninja-reg-10-cup-stainless-steel-specialty-coffee-maker/5372531?keyword=10-cup-coffee-makers https://www.bedbathandbeyond.com/store/product/ninja-reg-10-...
AnonC 6y ago
What’s even more confusing, I think, is that even if someone defines one cup as a specific volume, approximately how much of a specific kind of coffee grounds or a specific instant coffee have to go into it? There can also be huge variations in the proportion of water used for black coffee, for example. I’m looking for some way to get the caffeine content of specific coffee types and brands, even if those are approximate.
standardUser 6y ago
Brewed coffee varies so much in potency, I'm not even sure how much the quantity of the liquid even matters. A shot of coffee that has been cold brewed with finely ground beans for 48 hours is dramatically more potent than a giant cup of coffee brewed quickly with less-fine grounds and hot water.
- TheSpiceIsLife 6y ago
  From the Wikipedia article: Caffeine is moderately soluble in water at room temperature (2 g/100 mL), but very soluble in boiling water (66 g/100 mL). Caffeine is 33 times more soluble in hot water! What matters more, then, is the concentration of coffee grounds to water, and how much of that water is left in the grounds.
  - gattilorenz 6y ago
    > Caffeine is 33 times more soluble in hot water! On the other hand, you "boil" your coffee for 2 minutes, not 2880 minutes (48h). But I'm no chemist, so you might still be right, despite the different orders of magnitude. Also, we're not factoring in the water/steam pressure. Anybody volunteers for extracting coffee with an espresso machine for 48h?
  - standardUser 6y ago
    This doesn't have to be academic. You can do an experiment at home. Brew a big cup of coffee with a drip machine and drink it. Note how you feel. Then, make a batch of cold brew and let it sit for 48 hours. Drink half as much of that as you did the hot brewed coffee, but pease do so slowly as some people become very uncomfortable with that amount of caffeine.
    - KMag 6y ago
      Yes, cold brewed coffee can have much more caffeine than you'd expect given the smoothness of the taste. Back when my brother managed a coffee shop, the first time I popped into his work and asked his recommendation, he didn't warn me of the caffeine content. I was well habituated to caffeine, but quickly drinking 12 or 16 oz. of cold-brewed coffee left me feeling a bit dizzy, to the point I hung around the shop for a bit to make sure I was fine to drive.
smarx007 6y ago
In Europe, paper cups are usually 250ml (8.8oz) [1]. I presume German authors of this paper would have a similar volume in mind. [1]: https://www.tingstad.com/se-en/foodservice/disposable-cups/paper-cups/paper-hot-cup-bioware-25-30185769 https://www.tingstad.com/se-en/foodservice/disposable-cups/p... as an example
StevePerkins 6y ago
When I brew a pot of coffee, I fill it with water just past the line that represents 2x the number of cups I want. If I expect to drink 2 cups of coffee, then I fill it just past the "4" line. If I'm making a pot for multiple people and want 4 cups, then I fill it just past the "8" line. I think this is pretty normal. To the point where we don't even consciously think about it. In practice, a "cup of coffee" represents two cups as measured by the manufacturers. The manufacturers say that 6 oz is a cup, but a standard American coffee cup is 12 oz. I don't know why we don't simply make those match up.
- mumblemumble 6y ago
  > I don't know why we don't simply make those match up. There are already so many units called the "cup". If we do anything along those lines, perhaps we instead define a new unit, the 'mug', that is equal to exactly two US coffee cups (12 US ounces, 1.5 US cups, 1.44 UK cups, 2.4 lungos, 0.75 Starbuckses) of coffee. Related: https://xkcd.com/927/ https://xkcd.com/927/
bqlou 6y ago
Glad I learned to drink coffee the italian way : one expresso cup (20/40ml). Strong, fruited, less caffeine. Loving it every morning.
catilac 6y ago
The instructions I follow for my pourover requires 350 grams of water. Much more than 8oz. It drives me crazy, but it also tastes good! Though If I only poured until reaching the 8oz mark it's also quite nice. That said, there is a question of "full-extraction".
- m3kw9 6y ago
  Usually the ratio is 1:16 for full extraction without bitterness @200f with grain size slightly larger than refined sugar. That’s to maximize taste, without regard for nutrients. The bitter compounds probably make no difference.
hoorayimhelping 6y ago
And for that matter, how does the brewing method of coffee play into the health benefits? If I brew really strong coffee, do I get concentrated antioxidants and plant goodness? If I brew weak coffee and drink a lot of it over a longer period does that help my body's uptake of it? Not that knowing these answers will really change my coffee drinking habits, as this seems like a ridiculous micro optimization, but it would be nice to know a bit more about the mechanism here.
- mchristen 6y ago
  Not to mention that processing and roasting also changes the bean and the resulting coffee brewed from it.
srg0 6y ago
Measuring weight of the dry ground coffee describes the actual consumption better. The standard espresso quantity is 7 g of ground coffee per cup (25 ml).
octagonal 6y ago
Well, there does exist this standard by the Specialty Coffee Association specifically intended as a reference for testing: https://sca.coffee/research/coffee-standards https://sca.coffee/research/coffee-standards It suggests that the 'cupping vessel' be "between 7 and 9 fluid ounces (207 ml to 266 ml), with a top diameter of between 3 and 3.5 inches (76 - 89 mm)"
fnbr 6y ago
For me, I use 20g of coffee, ground to a 20 on a Baratza Virtuoso, with a 275mL of water in a French press, brewed with boiling water for 4 minutes. If you change any of these variables- grind size, water temperature/volume, amount of coffee, etc, you drastically change the caffeine content.
karmakaze 6y ago
It's already confusing enough before using another ambiguous unit. 1 us fl oz = 0.96076 * uk fl oz

hprotagonist 6y ago

“coffee cup” is a semi-standard unit just like the ones you listed are. And yes, it’s about 6 fluid ounces, and no, nobody in the real world means “i drank 6 fluid ounces of coffee” when they say “i had a cup of coffee”. Overloading is fun!

varnisher 6y ago
Instead of measuring coffee you could measure caffeine content, but a lot of effects may be in non-caffeine ingredients. Still, it's a first step.
- lowmemcpu 6y ago
  That's what led me down this path. Searching the internet for "how much caffeine is in a cup of coffee" leads to the question of "what is a cup?", "how did you brew it?", "what kind of grounds did you use?".
  - hprotagonist 6y ago
    the real world is very nonlinear.
- hprotagonist 6y ago
  “total dissolved solids” is a more comprehensive measure of coffee strength for the entourage effects reason.

jcims 6y ago

I think the cup count is useful from the habit standpoint, but the study should probably also include style of coffee or caffeine content. If I drink brewed coffee I’m on a steady flow for the day, sometimes making a second pot in the afternoon. I bought an espresso machine about a year ago, and one Americano in the morning pretty much sets me up for the whole day.

dcolkitt 6y ago

I've been confused by this for a while as well. The answer seems to be there's not such thing as a "true" cup of coffee. It pretty much just means whatever the respondent considers a cup. (In contrast to studies on alcohol consumption, where researchers have standardized units. And even on surveys will make sure to clarify with respondents so they get responses in normalized units.)

jschwartzi 6y ago
There's an ISO standard for how to brew tea for laboratory comparison: https://en.wikipedia.org/wiki/ISO_3103 https://en.wikipedia.org/wiki/ISO_3103 Also here are all the ISO standards for coffee: https://www.iso.org/committee/47950/x/catalogue/p/1/u/0/w/0/d/0 https://www.iso.org/committee/47950/x/catalogue/p/1/u/0/w/0/... They don't yet have any brewing standards but a lot of what they seem to do is by nose with green or roasted ground coffee.

paulcole 6y ago

Many commercial coffee makers use 5 ounces when calculating the number of cups they serve. Scroll down to the comparison chart and look at the carafe sizes: https://www.bedbathandbeyond.com/store/product/ninja-reg-10-cup-stainless-steel-specialty-coffee-maker/5372531?keyword=10-cup-coffee-makers https://www.bedbathandbeyond.com/store/product/ninja-reg-10-...

AnonC 6y ago

What’s even more confusing, I think, is that even if someone defines one cup as a specific volume, approximately how much of a specific kind of coffee grounds or a specific instant coffee have to go into it? There can also be huge variations in the proportion of water used for black coffee, for example. I’m looking for some way to get the caffeine content of specific coffee types and brands, even if those are approximate.

standardUser 6y ago

Brewed coffee varies so much in potency, I'm not even sure how much the quantity of the liquid even matters. A shot of coffee that has been cold brewed with finely ground beans for 48 hours is dramatically more potent than a giant cup of coffee brewed quickly with less-fine grounds and hot water.

TheSpiceIsLife 6y ago
From the Wikipedia article: Caffeine is moderately soluble in water at room temperature (2 g/100 mL), but very soluble in boiling water (66 g/100 mL). Caffeine is 33 times more soluble in hot water! What matters more, then, is the concentration of coffee grounds to water, and how much of that water is left in the grounds.
- gattilorenz 6y ago
  > Caffeine is 33 times more soluble in hot water! On the other hand, you "boil" your coffee for 2 minutes, not 2880 minutes (48h). But I'm no chemist, so you might still be right, despite the different orders of magnitude. Also, we're not factoring in the water/steam pressure. Anybody volunteers for extracting coffee with an espresso machine for 48h?
- standardUser 6y ago
  This doesn't have to be academic. You can do an experiment at home. Brew a big cup of coffee with a drip machine and drink it. Note how you feel. Then, make a batch of cold brew and let it sit for 48 hours. Drink half as much of that as you did the hot brewed coffee, but pease do so slowly as some people become very uncomfortable with that amount of caffeine.
  - KMag 6y ago
    Yes, cold brewed coffee can have much more caffeine than you'd expect given the smoothness of the taste. Back when my brother managed a coffee shop, the first time I popped into his work and asked his recommendation, he didn't warn me of the caffeine content. I was well habituated to caffeine, but quickly drinking 12 or 16 oz. of cold-brewed coffee left me feeling a bit dizzy, to the point I hung around the shop for a bit to make sure I was fine to drive.

smarx007 6y ago

In Europe, paper cups are usually 250ml (8.8oz) [1]. I presume German authors of this paper would have a similar volume in mind. [1]: https://www.tingstad.com/se-en/foodservice/disposable-cups/paper-cups/paper-hot-cup-bioware-25-30185769 https://www.tingstad.com/se-en/foodservice/disposable-cups/p... as an example

StevePerkins 6y ago

When I brew a pot of coffee, I fill it with water just past the line that represents 2x the number of cups I want. If I expect to drink 2 cups of coffee, then I fill it just past the "4" line. If I'm making a pot for multiple people and want 4 cups, then I fill it just past the "8" line. I think this is pretty normal. To the point where we don't even consciously think about it. In practice, a "cup of coffee" represents two cups as measured by the manufacturers. The manufacturers say that 6 oz is a cup, but a standard American coffee cup is 12 oz. I don't know why we don't simply make those match up.

mumblemumble 6y ago
> I don't know why we don't simply make those match up. There are already so many units called the "cup". If we do anything along those lines, perhaps we instead define a new unit, the 'mug', that is equal to exactly two US coffee cups (12 US ounces, 1.5 US cups, 1.44 UK cups, 2.4 lungos, 0.75 Starbuckses) of coffee. Related: https://xkcd.com/927/ https://xkcd.com/927/

bqlou 6y ago

Glad I learned to drink coffee the italian way : one expresso cup (20/40ml). Strong, fruited, less caffeine. Loving it every morning.

catilac 6y ago

The instructions I follow for my pourover requires 350 grams of water. Much more than 8oz. It drives me crazy, but it also tastes good! Though If I only poured until reaching the 8oz mark it's also quite nice. That said, there is a question of "full-extraction".

m3kw9 6y ago
Usually the ratio is 1:16 for full extraction without bitterness @200f with grain size slightly larger than refined sugar. That’s to maximize taste, without regard for nutrients. The bitter compounds probably make no difference.

hoorayimhelping 6y ago

And for that matter, how does the brewing method of coffee play into the health benefits? If I brew really strong coffee, do I get concentrated antioxidants and plant goodness? If I brew weak coffee and drink a lot of it over a longer period does that help my body's uptake of it? Not that knowing these answers will really change my coffee drinking habits, as this seems like a ridiculous micro optimization, but it would be nice to know a bit more about the mechanism here.

mchristen 6y ago
Not to mention that processing and roasting also changes the bean and the resulting coffee brewed from it.

srg0 6y ago

Measuring weight of the dry ground coffee describes the actual consumption better. The standard espresso quantity is 7 g of ground coffee per cup (25 ml).

octagonal 6y ago

Well, there does exist this standard by the Specialty Coffee Association specifically intended as a reference for testing: https://sca.coffee/research/coffee-standards https://sca.coffee/research/coffee-standards It suggests that the 'cupping vessel' be "between 7 and 9 fluid ounces (207 ml to 266 ml), with a top diameter of between 3 and 3.5 inches (76 - 89 mm)"

fnbr 6y ago

For me, I use 20g of coffee, ground to a 20 on a Baratza Virtuoso, with a 275mL of water in a French press, brewed with boiling water for 4 minutes. If you change any of these variables- grind size, water temperature/volume, amount of coffee, etc, you drastically change the caffeine content.

karmakaze 6y ago

It's already confusing enough before using another ambiguous unit. 1 us fl oz = 0.96076 * uk fl oz