Beautiful, rich, and exceedingly bitter espresso - Page 3

Beginner and pro baristas share tips and tricks.

#21: Post by GlennV »

Dear Jim,

Thanks for this, and the slides and your other recent comments on the subject - it's all very thought provoking. Can I just though ask you to clarify what you mean by "keeping the flow the same", when decreasing the dose and making the grind finer in attempt to extract more caramels. This could mean getting the same beverage weight in the same time, but I presume you don't mean that as too many things would be changing. Another possibility would be getting to the same brew ratio in the same time, in which case the increase in extraction would solely be the result of the finer grind - but when I've tried this the effect is rather subtle. Alternatively, it could mean reaching blonding at the same brew ratio, after a longer time - so that the increased extraction is partly a result of the finer grind and partly the result of longer contact time. I suspect the latter is the intention, but wished to confirm.

To put some numbers on it, made up but hopefully representative, if you have a shot blonding at

15g dose, 30g beverage in 25s

and make the grind finer so that you get the same 30g from 15g in 29s say, or need to reduce to 13g to get the same absolute flow.

You could perhaps choose

13g dose, 30g bev in 25s (I don't think you mean this) or
14g dose, 28g bev in 25s (same brew ratio, same time) or
14.5g dose, 29g bev in 27s (same brew ratio, same blonding point perhaps - sort of splitting the difference.)

(the numbers are chosen such the flow, in g/s, is inversely proportional to dose)

I'm not suggesting that you're thinking about these details when making the changes, I'm just wondering what the rough idea is. Even though the numbers are close in the example, the taste could be quite different in these cases. Thanks.

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#22: Post by mitch236 »

Keeping the flow constant means getting the same mass of liquid in a set amount of time. So if you grind finer, you would reduce the dose of grounds to keep the flowrate the same. If you grind coarser, you would increase the dose to keep the flowrate the same. You can just observe the flowrate as the shot is brewing instead of weighing everything and as you gain more experience with your equipment, you will know that x change in grind causes y change in flow and that z change in dose will correct that change and keep the flow the same.

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#23: Post by another_jim »

Yep, that is what I meant.

You can weigh the shots if you like, and make your dose adjustments to keep the flow rate proportional to the dose, so you get the same shot concentration in the same time. That would be preferable in theory; but I do not know how much difference it makes in practice. In practice, the bulk of the extraction is done in about 20 seconds, and if you run the shot to the blonding point, you get roughly the same concentration without weighing. The only difference is that shots vary from 25 to 35 seconds rather than taking the same amount of time.

Right now I'm using a lever where one can adjust the rate of flow by manipulating the lever pressure. This does change the taste, but I can't yet describe the taste change analytically (i.e. in away that allows it to be understood and controlled) or figure out why.
Jim Schulman


#24: Post by GlennV »

another_jim wrote:Yep, that is what I meant.
Then I'm puzzled (assuming it's mitch236's interpretation you're referring to). My current favourite technique, which is fairly common now I think, is to fix dose and beverage weight and vary grind by taste - ignoring timing. Going finer increases extraction both directly, because the increased surface area, and indirectly, by slowing the shot and increasing contact time. As you are always comparing drinks at roughly the same concentration it's pretty easy to taste the degree of over or underextraction and home in rapidly on the tastiest shot at that recipe. However, if you want to try the effect of a different dose then you have to do it all over again. So, it's a robust approach but inefficient. Your approach seems much more efficient, and indeed uses more information - the colour of the stream. I'm keen to understand how this works, both for that efficiency and for the insights it must inevitably give into the extraction process. Now, I thought what you were saying was that as you move the grind finer, for example, then you also reduce the dose a bit so the shot doesn't slow up quite as much - keeping closer to the region where shots are blonding around the desired brew ratio perhaps. But, if I understand your reply correctly, you're actually going further than that and keeping the shot time the same or even faster (before your adventures in lever land that is) - so that any increased extraction is solely due to the increased surface area. I'll have to try this.

By the way, I quite like visualising those extraction vs time curves with (weight in cup)/(dose) as the independent variable, instead of time. Concentration of the stream (colour) is then the gradient of the graph. A desired brew ratio & extraction% is a point on the graph which you can pass through with various gradients.


#25: Post by mitch236 »

The way I look at dialing in a coffee is dividing the process into two parts. One part is acid/bitter balance, the other is acid-bitter/sweetness balance. Forgetting temps for a minute, I usually dial in acid/bitter first (you should pay attention to sweetness too as you really work on both together). Flow controls that balance with faster flow accentuating acids and slower bitters. Higher extractions favor sweetness. If you have good acid/bitter balance and want more sweetness then you would grind finer but also reduce the dose to keep the flow (acid/bitter balance) constant. I hope this helps.

I used to vary the grind to dial in acid/bitter balance but found its much easier just to change the dose. Because you want to affect flow, you could either change the grind (and waste coffee and be less precise) or alter the dose. So if you want to slow the flow and accentuate bitters you would keep the grind the same and increase the dose say 0.5 Gm.

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#26: Post by another_jim »

GlennV wrote:My current favourite technique, which is fairly common now I think, is to fix dose and beverage weight and vary grind by taste - ignoring timing.
I've never tried this; I always change dose to compensate for a grind change. I have an aesthetic of how an espresso should flow, and to see either a dribble and gush is visually painful to me. But I have to admit, I have no idea how it would work in terms of taste
Jim Schulman


#27: Post by GlennV »

another_jim wrote:I have an aesthetic of how an espresso should flow, and to see either a dribble and gush is visually painful to me.
Me too (although perhaps I'm imagining what it might taste like). I don't think anyone's suggesting deliberately making chokers and gushers; I was talking about small changes around the margins.