You would have seen your barista in your local coffee shop tamping down the coffee before it is brewed. Is this just about the look and image or is tamping an important part of the process?
What Does Tamping Do?
Tamping is pretty crucial for one main reason. Tamping essentially eliminates any voids in the coffee in your porta filter. This ensures that your coffee grinds are evenly compressed so that you get an even extraction. The water will then pass through all of the coffee at the same rate of speed. Let’s apply some laws of physics here-the brew water will, under pressure, find the path of least resistance through the coffee. If it does find any voids in the coffee it will rush through them over extracting the coffee surrounding these channels and under extracting the coffee in the channels. In terms of taste what you get in the cup could taste bitter and what is left behind in your porta filter could have all the great flavour. It also is an immediate answer as to wther your dosing is correct or not.
How to Tamp Properly
After you have dosed correctly even it out before you tamp. If you don’t even it out it will be hard to compact properly. Take your tamper and ensure that you are tamping on a surface where you can leverage your body and arm weight. This will take some experience and practice but tamp with 30-40 pounds of pressure. This will evenly compact all of the coffee. The procedure popular with baristas is to ‘staub tamp’ whereby you tamp the coffee 4 times riding the tamper up against the inside-North, South, East and West edge of the basket. As you release each tamp slightly twist the tamper to polish the surface of the coffee.
How You Know You are Tamping Correctly
To be honest this will all be in the final taste. But there are clues you can look for. If you see ‘worm holes’ in what is left in the porta filter this indicates that the coffee was not properly packed.
Equipment Required
Many espresso machines provide you with plastic tampers. Throw them away! Buy yourself a good quality tamper that will fit snugly into your porta filter. But what do we mean by a good tamper?
What to Look for When Buying a Tamper
Size-make sure it fits your porta filter. Diameters can range from 49-60mm so measure up properly.
Weight-buy a tamper that has a good weight to it.
Rounded v flat bottom-You will see that some have a convex tamping surface, this is really about personal preference.
In Summary
Look and style-may not matter to all but if you are willing to spend good money on quality beans and a quality coffee machine don’t then skimp on the look and quality of the tamper!