What is the effect of pulling a shot longer than 26 seconds?

When a shot of espresso is pulled longer than 26 seconds, it typically leads to over-extraction. This occurs because the hot water has more time to interact with the coffee grounds, causing it to extract additional flavors that are not desirable. The initial flavors from the coffee, such as sweetness and acidity, are usually extracted in the first 20 to 25 seconds. Once the extraction extends beyond this optimal range, the water starts to draw out bitter compounds and undesirable tastes, which can make the espresso taste harsh or overly bitter.

In contrast, under-extraction happens when the shot is pulled too quickly, limiting the extraction of important flavors, whereas a balanced flavor profile is more likely achieved within the optimal time range. A cleaner taste is also associated with proper extraction and timing. Therefore, pulling a shot for longer than 26 seconds leads to the situation where the coffee becomes over-extracted, resulting in a less pleasant flavor experience.