Have you tried drinking a shot of espresso? If extracted well, it can be really sweet! Extraction is important to produce a balanced shot. A bad extraction might lead to sour, bland or a bitter cup. A good extraction will produce a tasty cup of coffee. This is the primary component of coffee with milk beverages so it is vital to make a good shot of espresso.
Use a weighing scale to weigh the beans you are going to use so that the amount of coffee to be used will be precise. You can start with 18g using a double basket portafilter. Check the grind size and calibration of the espresso. If it takes too long to drip and finish the extraction, grind a bit coarser; if it drips too fast, make the grind size tighter.
Tamping is an important step to create a good extraction. If we have made an uneven tamping, you'd notice that the coffee would not come out at the same time. Don't forget to clean the sides of the portafilter too before locking it to the group head, this will help you have a clean extraction because some of the grounds might scatter to your espresso shot. Always flush the group head before and after you take the shot. This will help clean the grounds remaining from the previous shot.
Press the timer as soon as you put the portafilter in and push the button to extract coffee. Timing is essential in making coffee. Remember to tare the scale to get the right amount of shot. Aim an output of 30-35ml and watch the timer too (about 20-30 seconds).
You can also take a look at the shot pouring out from the spout. You can stop before you get the white streaks which will lead to over extraction and bitterness of the coffee. The aim is a balanced espresso shot. Try it if you find any sharpness and make your mouth pucker? Does it taste bitter and uneasy on the palate? Does it have a long finish which means that the taste lingers in your mouth after taking a sip? Does it taste sweet and make you smile? Sometimes, it's that sort of feeling that you get and you'd know this would be a lovely shot.
We use the ristretto (highly concentrated espresso) at Cube. We'll talk about this on another entry.
Practice always helps our skills to improve. Taste your espresso shot, share it and get feedback from the people around you.