This pic looks so good, you can almost taste it, but chances are if you didn't tamp it well it won't look like this. So what is tamping?
Whether brewing espresso in a machine or a stovetop espresso maker, a good tamper is an essential part of the coffee-making process.
What is a Tamper?
Tampers are tools used to pack (or "tamp") espresso grounds into the basket of an espresso machine. They will help you pack the grounds evenly for that quality shot, converting a loose pile of 'dosed' grounds to a tightly compressed cake inside the basket.
Why Tamp at all?
Baristas understand that you should put a lot of effort into perfecting your tamp. Beyond the grind and the timing, proper tamping is key to pulling a quality shot of espresso, and there's a science behind tamping.
When pulling a shot, pressurized water is sent through the portafilter and into the coffee ground-filled basket. If those grounds are left in a loose pile, the water shoots right through them, often finding cracks or the easiest route possible and avoiding more difficult sections. This is not ideal for picking up the full flavour of the coffee beans.
When the coffee grounds are tamped, the water needs to force its way through the pile. This means that the water is interacting with the coffee longer and running through the entire cake of grounds. This combination of time and distribution results in a fuller flavour for the espresso shot.
Tamping also compacts the grounds enough to leave a little room for the coffee to swell as water is added. This is a secondary purpose though it does help keep your machine's group head clean.
We will explain how to tamp correctly in our next post, so stay tuned.