Today, it might be well rounded, but tomorrow, the same beans and machine, same everything, will give you something sharp or sour. It’s like a box of chocolates, if you will, especially for the new people. And it’s almost never down to fate, but something that is different in what you do. That’s the thing with espresso; it’s very delicate, there are so many variables, like the dose, the grind, the flow, the time. So, if one of these variables is altered a little bit, the taste will be altered as well. So, you don’t have to achieve the ultimate shot, but you have to be consistent. And when you are consistent, then you can really work on it.
Begin with the variables that you can control. Use the same quantity of ground coffee for each shot, and don’t estimate with a scoop. If possible, use a scale to measure the dose before grinding and the shot volume after brewing. Regulate the shot time by adjusting the grind, not by tamping harder or softer (when the shot is slow, the first instinct of most people is to tamp more firmly, but that usually leads to channeling). If the shot is too long, grind a bit finer; if too short, grind a bit coarser. Think of grind setting as the primary rudder that governs flavor and shot time.
One of the most destructive tendencies when you get a bad shot is to change 3 things at once. When your shot is too bitter you want to up the dose, change the grind, and lengthen the shot all at once, and figure that one of them will fix it. The problem with this method is that you will never know which one fixed your shot. Change one thing and try again. If it tastes better, then keep going down that path. If it doesn’t, go back to where you were, and change something else. Each shot is data, not a failure or a success. Even a bad shot can tell you something about what is happening with your machine and your coffee.
A basic routine might involve 15 minutes each day. Sip one shot as you normally would and note the acidity in the front of your tongue and bitterness in the back. Grind a bit finer or coarser, and then pull another shot directly after so you can compare the two shots directly. Direct comparison of two shots builds your palate much faster than drinking just one a day without comparison. If you have time for a third shot, the change can be confirmed to be in the correct direction or not. You might feel bad pouring out the first shot, but it’s saving you from pouring out 10 bad shots down the line.
If you get stuck, look to your prep technique, not your machine. Channeling, in which water seeks out the easiest route through the puck, can be caused by grounds not being evenly distributed in the basket. Gently rapping the basket or flattening the grounds before tamping will facilitate a smooth flow of water. Similarly, the age of your beans is a huge factor; beans that have been sitting for too long after the can has been opened will always taste flat and dead, even if you do everything else right. Getting your technique consistent first makes flavor deviations easily explainable, and you don’t feel like you’re just spinning your wheels.