When you're trying to make great espresso shots you need to pay attention to a variety of elements and understand how espresso is extracted from coffee. At some point or another, we have all had a coffee that tastes really bitter and acidic or it tasted sour, thin and watery: these are signs that the espresso hasn’t been extracted correctly.
There are 3 things you need to get right to extract your espresso correctly:
1. THE DOSE
Make sure you have the correct amount of ground coffee in your basket, for example, if you are using a single basket have at least 9g or a double basket at least 18g of coffee. You can weigh the coffee or you can visually check after you have tamped (there is a groove that runs around the inside of the basket, if you can see that groove you are under dosing).
2. THE TAMP
Consistency with tamping pressure is crucial as this affects the speed at which the water can flow through the ground coffee. You should be aiming for a tamping pressure of 10-12Kg each time. If you aren’t using a calibrated tamp, use your kitchen or bathroom scales to check your tamping pressure.
3. THE GRIND
If the coffee is ground too fine the shot will be too slow, if it is ground to coarsely the shot will be too fast. For most espresso machines you are looking for a texture similar to table salt. There are 2 reasons why you may need to adjust your grind: the age of the roasted beans, or, humidity and temperature.
How Do I Know My Espresso Shot Is Good?
When an espresso shot has been correctly extracted you get a balance of three key components:
If an espresso is extracted too quickly it will taste sour and feel thin and watery on the palate, because the sugar and oil are missing.
If an espresso is extracted too slowly it will taste overly bitter and acidic, because too much of the acid has been extracted.
What Is A Good Extraction Time For Espresso?
USING A SINGLE BASKET: A pour of 30mls including crema running for 25-30 secs from a single 9g basket.
USING A DOUBLE BASKET: A pour of 30mls including crema running for 15-20 secs from a double 18g basket, or, a pour of 60mls including crema running for 30-35 secs from a double 18g basket.