Does Tamping Pressure Affect Espresso Extraction? How Much Pressure Should You Apply When Making Espresso

The Importance of Tamping in Espresso Extraction

Using a tamper to compact the coffee puck is a crucial step in espresso extraction. The discussion has historically focused on how to achieve a level tamp. Uneven tamping often leads to inconsistent extraction.

Different Perspectives on Tamping Pressure

However, opinions vary on whether tamping pressure affects espresso extraction. Some baristas believe that tamping pressure should be properly controlled, as excessive force can compact the coffee grounds too tightly, slowing the flow rate. Others argue that as long as the puck is level and firm, the amount of pressure applied doesn't significantly matter, as manual tamping force is negligible compared to the extraction pressure of an espresso machine.

FrontStreet Coffee's Tamping Pressure Experiments

FrontStreet Coffee has also conducted experiments on tamping pressure. When FrontStreet Coffee used a Galileo grinder set at 1.6 grind setting to grind 18.5g of coffee grounds, then applied 1.8kg of tamping pressure after distribution, they extracted 37g of espresso liquid in 27 seconds.

Using the same grind setting and the same amount of coffee grounds, when applying 9kg of tamping pressure, extracting 37g of espresso took 36 seconds, with a noticeably slower flow rate and a 2-3 second delay in the initial extraction time.

However, when the grind was adjusted coarser to 2.2 setting, using 19.5g of coffee grounds, and applying 1.8kg of tamping pressure after distribution, 39g of espresso liquid was extracted in 28 seconds.

Similarly, using the 2.2 grind setting with 19.5g of coffee grounds, when applying 9kg of tamping pressure after distribution, 39g of espresso liquid was extracted, also taking 28 seconds.

Both scenarios used two different pressure levels yet yielded similar results, because the difference in coffee particle size caused variations in density.

Analysis of Results

In the first set of tests, the coffee grind was set to a finer setting, and differences in tamping pressure resulted in inconsistent puck density. Using 1.8kg of pressure, the puck was relatively less compact, resulting in lower density and faster flow rate. When using 9kg of pressure, the puck was more tightly compacted, resulting in a relatively slower flow rate.

In the set of tests with coarser coffee grinding, regardless of the tamping pressure applied, the gaps between coffee particles in the puck were definitely larger than in the previous set with slightly finer grinding. Whether using 1.8kg or 9kg of pressure, the puck was essentially compressed to its maximum density. Therefore, the flow rates and extraction times for both pressure levels were similar, with minimal impact.

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