Surface Area & Agitation

3- Surface Area & Agitation:

To make the reaction happen between the water and the coffee beans there has to be contact, the contact varies depending on how much surface area there is.

The finer the bean is ground, the more surface it has, because that makes it have bigger area to volume ratio. The smaller the particle size, the higher the number of solutes will be extracted.

That’s why the grind is an important parameter of making coffee. Also it’s important that all coffee particles have the same surface area to volume ratio (all ground to the same level).

That way, the coffee will be evenly extracted. Otherwise, the bigger pieces will release fewer solutes than the smaller ones, causing each unit to release inconsistent amounts of solutes during extraction. This results in a portion of the coffee being over-extracted, and another under-extracted in the same cup.

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