How does grind size affect espresso extraction?

Grind size plays a crucial role in espresso extraction because it directly influences the surface area of the coffee particles that come into contact with water. When using finer grinds, there is a greater surface area exposed to the extraction process. This means that water can interact more effectively with the coffee grounds, allowing for quicker and more efficient extraction of flavors, oils, and soluble compounds. As a result, finer grinds help achieve a higher strength and richness in the espresso shot, as more of the desirable components dissolved from the coffee are extracted.

In contrast, using coarser grinds would result in less surface area, leading to a shorter extraction and potentially a weaker flavor profile. Therefore, understanding the proper grind size is essential for baristas who aim to maximize the quality of their espresso.