Jonathan Gagné
Astrophysicist and coffee researcher; author of The Physics of Filter Coffee and The Physics of Espresso, and writer of the Coffee ad Astra blog on brewing science and equipment.
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Their wordschanging the dripper diameter, keeping all other important variables fixed, has no impact on the brew mechanics and the resulting cup, in an "idealized" scenario
↗The Importance of Bed Depthcoffeeadastra.com 1st of 3 in this piece
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Their wordsthe depth of a coffee bed, contrary to the width of the coffee bed, is a variable that impacts the flavor of the coffee being brewed significantly, and in a way that you cannot easily compensate for by changing other brew variables.
↗The Importance of Bed Depthcoffeeadastra.com 2nd of 3 in this piece
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Their wordsthe coffee bed would act on these molecules by filtering them out a bit like oxygen adsorbers keep oxygen in; it just provides a gigantic maze of free surface area for them to stick on, and hopefully the microscopic fluid velocity is gentle enough to not drag them along.
↗The Importance of Bed Depthcoffeeadastra.com 3rd of 3 in this piece
- 2 years earlier
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Their wordsConical burrs appear on average less unimodal and less uniform, although there is a large overlap meaning that one can easily find a specific flat burr that is less unimodal and less uniform than a specific conical burr.
↗What I learned from analyzing 300 particle size distributions for 24 espresso grinderscoffeeadastra.com 1st of 3 in this piece
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Our reading
Grinders that produce fewer fines (more unimodal) also tend to produce more uniform particle sizes.
Their wordsContrary to popular hearsay, more unimodal grinders appear to also be more uniform on average.
↗What I learned from analyzing 300 particle size distributions for 24 espresso grinderscoffeeadastra.com 2nd of 3 in this piece
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Our reading
Burr geometry matters more than burr size for how uniform and unimodal a grinder's output is.
Their wordsIt therefore appears that burr geometry may be more important than burr size in determining unimodality and uniformity.
↗What I learned from analyzing 300 particle size distributions for 24 espresso grinderscoffeeadastra.com 3rd of 3 in this piece
- 14 months earlier
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Their wordsThe case of astringent compounds is particularly interesting, because they require a very high temperature to be dissolved efficiently in water.
↗The Mechanism Behind Astringency in Coffeecoffeeadastra.com 1st of 3 in this piece
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Their wordsTherefore, avoiding astringency is not directly a matter of flow evenness, it is actually a filtration problem !
↗The Mechanism Behind Astringency in Coffeecoffeeadastra.com 2nd of 3 in this piece
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Their wordsGrinding too fine will liberate a lot more astringent compounds by breaking more coffee cells, which will result in an astringent cup regardless of how even the water flows through the coffee bed.
↗The Mechanism Behind Astringency in Coffeecoffeeadastra.com 3rd of 3 in this piece
- 2 weeks earlier
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Their wordsI now suspect that adding a source of hydraulic resistance under the puck that is non-negligible compared with the espresso puck itself is desirable to reduce the impact of channels because it slows down the flow of water where it would tend to become otherwise too fast and as a consequence less even across the surface of the coffee bed.
↗More Even Espresso Extractionscoffeeadastra.com 1st of 2 in this piece
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Their wordsflat burrs tend to send the coffee preferentially on one side of the portafilter (to the right side with the design of EG-1), an effect probably worsened by the use of high rpm.
↗More Even Espresso Extractionscoffeeadastra.com 2nd of 2 in this piece