Scale vs. volume measurement for coffee bean dose

Beginner and pro baristas share tips and tricks.
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Balthazar_B

Postby Balthazar_B » Jul 08, 2019, 9:23 pm

In another thread, because he didn't have a scale, someone posted that he was using a volume measurement -- in this case, three level tablespoons, or approx 44.36 mL -- for 15 g of coffee for espresso. Since he was trying to optimize the grind for pulling shots, I thought there might be too much variability in the actual weight of his doses, and suggested he ought to consider getting a scale with a resolution of .1 g, just to get that variable under control. But then I wondered how much variability there was likely to be, so I did a little experiment.

I took nine samples of three level tablespoons -- trying for as much consistency as possible -- of the coffee I'm using right now (Scarlet City Warp Drive) and weighed each one in turn. Here are my results in grams:

  1. 17.3
  2. 18.2
  3. 17.3
  4. 16.9
  5. 16.7
  6. 17.4
  7. 16.9
  8. 16.9
  9. 17.6

So the average dose was 17.24g with a standard deviation of .464 g, and a maximum deviation of 1.3 g. I'll leave it to others more experienced than I to interpret the import of this, but I can say from experience with my lever machine, that a .4 g variance around 17g will necessitate adjusting the grind for optimal results.

FWIW, my take is that a decent scale is practically a necessity for dialing in the shot, and especially if one changes coffees from time to time.
- John

LMWDP # 577

emradguy
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Postby emradguy » Jul 08, 2019, 11:25 pm

That's a wider tolerance than Is be willing to accept.

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Carneiro

Postby Carneiro » Jul 09, 2019, 7:05 am

If I understand from the other post and from your experiment, you are weighting the whole beans.

A additional experiment (and protocol) would be weight the whole beans, grind them, and then trying to level the grounded coffee to the spoons again, adjusting with some ground beans if needed (or tossing some :cry:).

Anyway, in my experience, even the 1.3g difference makes not that big of impact on a double. But I understand that for some grinder and machine combinations this can be more drastic.

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Balthazar_B

Postby Balthazar_B » Jul 09, 2019, 8:41 am

Carneiro wrote:A additional experiment (and protocol) would be weight the whole beans, grind them, and then trying to level the grounded coffee to the spoons again, adjusting with some ground beans if needed (or tossing some :cry:).


Well, if I'm able to weigh the beans, then the only variable that matters is the grind, so I can leave the spoons in the drawer! :mrgreen:

I do realize that depending on the beans and roast, one may need to adjust the weight/grind of the dose with a given basket to get the best results, so this assumes one has dialed in the coffee already. A scale makes that a whole lot easier than eyeballing, of course.
- John

LMWDP # 577

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Carneiro

Postby Carneiro » Jul 09, 2019, 8:49 am

Ops, I mean measure the volume, then... :oops: :lol:

For sure the scale helps a lot! I use it every day and every shot, but is good to know how to use volume when there is no scale around.

Mrboots2u

Postby Mrboots2u » Jul 09, 2019, 9:28 am

Carneiro wrote:If I understand from the other post and from your experiment, you are weighting the whole beans.

A additional experiment (and protocol) would be weight the whole beans, grind them, and then trying to level the grounded coffee to the spoons again, adjusting with some ground beans if needed (or tossing some :cry:).

Anyway, in my experience, even the 1.3g difference makes not that big of impact on a double. But I understand that for some grinder and machine combinations this can be more drastic.

Define impact? hypothetically if a person is not weighing your shot out either and your eyeballing volume or colour , then you don't know what impact . You could be decreasing a dose by 1.3g and evening that out with a variable , non fixed output

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Carneiro

Postby Carneiro » Jul 09, 2019, 9:51 am

Exactly! :wink:

nuketopia

Postby nuketopia » Jul 10, 2019, 1:23 am

I've been at this espresso thing for a while.

The transition to dosing to weight and pulling the shot to weight and using the time as a QC check have really upped the game a lot. The old school methods and the superstitious methods have fallen away, at least for me, and have let me arrive at consistently great shots, time after time.

So, I say, weight, without a second though. One of the best investments have been the Acaia Luna scale for pulling shots, the Monolith Conical and A&D Scientific scale and the 270w at the weekend place. I don't measure volume anymore, just weights. Even milk for cappuccino I weigh now.

Back in the day, we'd all wonder why we couldn't get the same shot twice and why the great shots were so elusive.

Weighing everything changes that. Much easier to nail it.

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Balthazar_B

Postby Balthazar_B » Jul 10, 2019, 8:32 am

nuketopia wrote:Weighing everything changes that. Much easier to nail it.


Same reason why just about every chef worth his/her salt weighs ingredients rather than using volume when assembling components for a recipe. Many even do so with their liquids (as you're doing with milk) for the sake of precision and reproducibility.
- John

LMWDP # 577

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Peppersass
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Postby Peppersass » Jul 10, 2019, 2:42 pm

Being able to accurately achieve a target brew ratio is very important for dialing in espresso. A scale is required because shot volume correlates poorly with shot weight: 1) you can get similar volume with different levels of concentration (%TDS) and 2) crema makes it impossible to properly judge the volume accurately (it can be way off when you have a lot of crema.)

So long as a scale is required to weigh the shot, you might as well weigh the dose, even if you believe that half a gram of variation in the dose doesn't affect taste (which is not the case in my experience.)

However, while weighing both the dose and the shot may be the best advice for home baristas, it may not be the best approach for busy cafes. These days, I'm seeing more and more high-end cafes weigh their shots. Because it merely merely signals when to cut the shot, it doesn't add any time to pulling a shot. But very few of these cafes weigh the dose because that does add time. Instead, they tend to use grinders that offer timed dosing. This isn't super accurate, but is probably more accurate than dosing by eyeballing the volume of grounds.