Agitation refers to the process of stirring or mixing coffee grounds and water during the brewing process, either with a spoon or with the water stream from a kettle, increasing the interaction between water and grounds. Also known as turbulence, agitation ensures that all particles have complete and uniform contact with the water as it passes through the coffee bed for the entire brew cycle.
Agitation is important because it helps to evenly extract the flavours and oils from the coffee grounds, which results in a more balanced and consistent cup of coffee.
When coffee grounds are immersed in hot water, the water will extract the soluble compounds from the grounds. However, if the grounds are not agitated, the extraction process will not be even, resulting in a coffee that can taste uneven and unbalanced. Agitation helps to ensure that all the grounds are in contact with the water, allowing for a more consistent extraction.
Agitation also helps to prevent the formation of “channels” or “dead zones” in the coffee bed. These channels can form when the water flows through the coffee bed without disturbing the grounds, resulting in some grounds being over-extracted while others remain under-extracted. Agitation helps to break up these channels and ensures that all the grounds are exposed to the water and extracted evenly.
Different brewing methods may require different levels of agitation. For example, in manual methods like pour-over and French press, the agitation is usually achieved by stirring the coffee grounds and water manually. In automatic methods like drip coffee makers, the agitation is achieved by the machine itself.
Overall, agitation is an important step in the brewing process, because it helps to ensure an even extraction of the coffee’s flavours and oils, resulting in a more balanced and consistent cup of coffee.
See this article on agitation at Perfect Daily Grind website.
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