What is 'tamping' in the context of espresso preparation?

Tamping refers specifically to the process of compressing the coffee grounds in the portafilter before brewing espresso. This is a crucial step because the way the coffee is tamped affects the extraction of flavors during the brewing process. Proper tamping creates a uniform and level surface, ensuring that water flows evenly through the coffee grounds. When the tamping pressure is consistent and appropriate, it helps to achieve the ideal extraction time and quality, resulting in a balanced and flavorful espresso.

When comparing this with the other choices, adding water to the espresso is a different process that occurs after brewing, while measuring coffee beans is part of the preparation but does not directly relate to the espresso brewing process itself. Grinding coffee beans is also a distinct step that occurs before tamping; it transforms whole beans into fine grinds necessary for making espresso. Tamping is specifically about the compression of those grinds, making option B the only correct description of what tamping entails in espresso preparation.