# We’ve got it all wrong



## Blaven (Mar 24, 2019)

Don't shoot the messenger!

https://www.smh.com.au/national/international-scientific-study-says-your-barista-is-making-your-coffee-all-wrong-20200122-p53trn.html


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## jumpingbean (Feb 25, 2012)

You just beat me to it!

Espresso extraction paper (the academic paper)

A two minute speed read suggests their argument is that ~20g coffee and the shot time 20-30 seconds leads to partially clogged flow and therefore uneven extraction. We'd be better with less coffee, a coarser grind, ignoring shot time and getting consistent extraction.

However, they acknowledge that greater complexity of taste may be associated with the regions or over & under extraction. Therefore blending two shots might be best.

I have to say their analysis of ~20g shots and uneven extraction coincides with my experience. Whether you can get better taste another way is a different matter.

Jumpingbean


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## coffeechap (Apr 5, 2012)

Nothing new though, maxwells was talking about this last year


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## MWJB (Feb 28, 2012)

Already a thread on this here:

https://www.coffeeforums.co.uk/topic/49714-interesting-read/?do=embed


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## Mr Binks (Mar 21, 2019)

Blaven said:


> Don't shoot the messenger!
> 
> https://www.smh.com.au/national/international-scientific-study-says-your-barista-is-making-your-coffee-all-wrong-20200122-p53trn.html


 This quote alone makes my teeth itch!

* "Of course, bean efficiency is not high on in the list of what people want in an espresso.*

* It is the over and under-extraction of flavours, combined, that gives coffee its some of its complexity.*

* A more efficient shot is likely to have less complexity, the scientists concede.*

* But they have a solution to that: brew two shots of espresso, one over-extracted and the other under-extracted, and mix them together. Genius.*

Soooooo, you have come up with a 25% gain in efficiency per shot but in order to match the flavour complexity of the older method you now have to pull 2 shots.......

Not genius!


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## MWJB (Feb 28, 2012)

This bit is a little absurd, *"This highlights a fundamental problem in correlating a coffee beverage with refractive index measurements because there are countless ways to achieve a given EY. For example, examining our data reveals that one can obtain two 22% EY shots by keeping the brew ratio fixed and setting the GS to either 1.3 or 2.0. The chemical composition of the faster shot cannot be the same as the slower shot owing to molecular differences in solubility, dissolution rate, and resultant molecule-dependent impact on the refractive index. This result does not undermine our use of EY, but rather illustrates that the barista indeed needs to taste the coffee, rather than measure its solvated mass."*

It has nothing to do with refractive index, setting 2.0 achieves 22%EY, setting 1.7 achieves 23%EY, then the finer grind reduces permeability and EY starts to drop again to 22% at 1.3. This would be the case if you measured EY with scales too, and is also the case with drip brewing. EY goes up as you grind finer, you hit the ceiling and it drops again.

Do the 22% before and after hitting the ceiling taste the same? Unlikely and it's not suggested anywhere that they would. The real question is, if you dial in methodically, whilst tasting, why knowingly go so far as to see it drop, if you don't prefer the taste here?

EY preference always was/is correlated against taste preference, rather than presented as a specific ideal number/target. Disconcerting to see such straw men.


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