Grinding finer and lowering the dose to guide taste. Why not keep dose constant?

Beginner and pro baristas share tips and tricks.
bluecorr

#1: Post by bluecorr »

I've been doing some reading on the forum and my takeaway so far is that if you grind finer you're providing more surface area and are able to extract more flavour compounds (by more do we mean more sugars, acids, bitters, caramels or more of everything?). But it sounds like it's recommended that you also lower the dose so that flow of water stays pretty much the same, let's say between the standard 25-30 seconds. This is the bit I don't understand and without lots of trial and error dialling this experiment in, what flavour impact can you expect if you grind finer but don't lower the dose Vs lowering the dose.


To my mind, the water would spend a lot more time with the coffee and therefore extract more. So you'd have the dual effect of more surface area AND slower water flow. So is the recommendation so that you don't end up with an over extracted coffee? Water as a solvent would extract more if it has more surface area and/or spends more time with the coffee. But is there a different in flavour if the extraction is guided by one or the other?

I'm sure there are some good threads already but they didn't show up in the search. Could you please educate me? I don't get it

Thanks

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LBIespresso
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#2: Post by LBIespresso »

Scott Rao instagram post on overextraction: https://www.instagram.com/p/CEpOMIUAVlm ... fyy1ztxifk

I thought this was interesting and is relevant to your question.
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bluecorr

#3: Post by bluecorr »

Thanks for sharing. So if dose is kept the same and grind is finer you increase the risk of channeling which causes a less even extraction which can be damaging to flavour profile? Is that.... right?

Jeff

#4: Post by Jeff »

Some of it is also the difference between infusion and percolation brewing.

Infusion brewing of coffee is typified by a French press -- put the grinds in water, let them sit, and eventually pour off the extract.

Percolation brewing is what dominates in V60 or espresso -- there is a flow of water through a bed of coffee, usually "fresh" at the top

In infusion brewing, contact time is very important. You need to "soak" out the good stuff from the grinds without too much of the "bad" stuff.

With percolation brewing, flow rate is very important. You need to "pull" out the good stuff as the water flows past the grinds. While the shot may take 20, 30 seconds or longer, the time for any specific bit of water with a bit of coffee is very short.

bluecorr

#5: Post by bluecorr »

Jeff wrote:Some of it is also the difference between infusion and percolation brewing.

...

In infusion brewing, contact time is very important. You need to "soak" out the good stuff from the grinds without too much of the "bad" stuff.

With percolation brewing, flow rate is very important. You need to "pull" out the good stuff as the water flows past the grinds. While the shot may take 20, 30 seconds or longer, the time for any specific bit of water with a bit of coffee is very short.
Ah so are you saying that you need to ensure a fast enough flow rate in espresso? Is it because if the flow of water is too slow then it may extract undesirable flavour compounds (woody etc)? Is it because the grinds are so fine and that would be very easy to do?

I've never really understood why you have this 25-30 second shot time window that's recommended but the above would make sense to me.

Jeff

#6: Post by Jeff »

I was thinking not so much about selective extraction, but sufficient extraction. As a specific example, light and ultra-light roasted coffees tend to be more difficult to extract than medium or dark and often need some combination of finer grind, higher flow rate, more water (higher ratio) and even higher temperature to get the results the barista is looking for from the coffee. (This would be an intentional, experience-based deviation from the "18 g, 1:2, in 25 seconds" benchmark.)

okmed

#7: Post by okmed »


bluecorr

#8: Post by bluecorr »

Jeff wrote:I was thinking not so much about selective extraction, but sufficient extraction. .)
But does this mean that you should be aiming for a shot time of at least X seconds and don't be too concerned if that goes up significantly when you grind finer in order to extract more? I.e. if initial shot time is 27s and then decide to grind finer to extract more. Should I really care that shot time goes up to 60s for example?

bluecorr

#9: Post by bluecorr »

okmed wrote:This may be helpful ( I hope).

Espresso 101: How to Adjust Dose and Grind Setting by Taste
Thank you I had come across that. It's useful as instructions but doesn't really address the WHY of changing the dose to preserve flow rate

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LBIespresso
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#10: Post by LBIespresso »

bluecorr wrote:Thanks for sharing. So if dose is kept the same and grind is finer you increase the risk of channeling which causes a less even extraction which can be damaging to flavour profile? Is that.... right?
I think the point of what Rao was saying is the term "overextraction" is overused often instead of poorly extracted or unevenly extracted due to channeling. My takeaway is that regardless of method, flow rate, grind size, etc.., it is even extraction that we should aim to start with and adjust from there according to taste. This can be done by following the Espresso 101 link above. I looked at that countless times in my first 2 years of home espresso. Likely much more helpful for you than my link.

As for shot time, My typical shot time including pre-infusion/dwell time is around 1 minute and my shot ratio is 1.3/1. This is far from 2/1 in 36 seconds so don't get hung up on "rules." DO get hung up on consistency and only changing 1 parameter at a time. This will help your education more than anything. Also, enjoy the journey!
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