If an espresso made from medium roast beans has a 14% extraction, which dominant taste would be most likely?

An espresso with a 14% extraction is on the lower end of the optimal extraction range, which typically falls between 18% and 22%. When extraction is too low, the resulting flavor can lean towards being sour. This sourness is primarily due to under-extraction, where the desirable compounds such as sugars and oils haven’t been fully extracted from the coffee grounds. Instead, the extraction process has primarily pulled out the acids, which often leads to a bright and tangy flavor profile.

In contrast, higher extractions are likely to pull more balanced flavors, including sweetness and even bitterness, depending on the level of roast and the brewing time. However, given the specific percentage of extraction at 14%, the outcome will likely showcase a predominance of sour notes due to the insufficient extraction of the other, more balanced flavors that extract closer to the optimal range. Thus, the dominant taste from an espresso with 14% extraction is indeed most likely to be sour.