How does resting coffee impact water flow in coffee/espresso prep?

Discuss flavors, brew temperatures, blending, and cupping notes.
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#1: Post by Auctor »

This morning I had the rare opportunity to test three very different beans in my ghost burr grinder, and discovered that my day old freshly roasted Ethiopia (Ikawa bean) and my Blue Bottle Exceedingly Rare Panama Finca Geisha have the same grind setting (4) but my Verve Ethiopia Hala Beriti has a setting of 7 (which is much coarser).

I've seen this pattern before, where my freshly roasted Ikawa coffee requires a much finer grind to achieve a 2:30 draw down time in my v60, compared to various SO coffees I've purchased from Trade and elsewhere (all claiming to be freshly roasted, all consumed with 3-5 days of opening the bag).

So it got me to thinking about how "rest" physically impacts the bean and, as a result, may change how the bean is prepared for either brew or espresso.

Why does a day old freshly roasted bean require a finer grind? Is it possible that all freshly roasted coffee requires a super fine grind at first, and then becomes coarser as the beans are either exposed to oxygen or degassed? Does origin or green prep (washed vs natural) impact flow as well? What are some basic principles of how the roast impacts how water flows through the beans?

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#2: Post by yakster »

Instead of comparing three different coffees from three different roasters with different roast dates you might be able to draw some valid conclusions from comparing the same coffee roasted by you on different days.

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