What role does grind size play in coffee preparation?

Grind size plays a crucial role in coffee preparation primarily because it influences the brewing time and extraction of flavors from the coffee grounds. When coffee is brewed, the size of the coffee particles affects the surface area exposed to water. A finer grind increases the surface area, allowing for quicker extraction of flavors, while a coarser grind reduces the surface area, leading to slower extraction.

This means that if the grind size is not properly matched to the brewing method, the resulting coffee can either be over-extracted, resulting in bitter flavors, or under-extracted, leading to a sour or flat taste. For example, espresso requires a fine grind to achieve optimal pressure and extraction in a short brewing time, while a French press uses a coarse grind to allow for longer steeping without over-extraction. Thus, the grind size directly impacts how efficiently flavors are extracted, which is vital for achieving the desired taste of the final brew.