Espresso is an extremely temperamental brew method, the tolerances for each aspect being so fine that the slightest change in one can result in an unusable shot. To properly pull an espresso shot, you will need good equipment, fresh coffee, and patience! The variables you’ll need to work with are:
Grind: espresso requires a very precise, fine, even grind
Dose: how much coffee goes into the portafilter
Distribution: how that coffee is evenly moved around in the portafilter
Temperature: ensuring the machine is running water through the coffee at the right temperature
Yield: the weight/volume of the resulting shot
Time: how long the shot pulls for
Our parameters for pulling a double shot of espresso are:
Dose: 18 - 21 grams
Temperature: 200 +/- 3 degrees
Time: 25-30 seconds
Yield: 1.5-2oz or 35 - 45 ml
If a shot pulls improperly (right amount of coffee yield in the wrong amount of time or vice versa), the barista can work with the grind (finer grind, slower pull), the dose (more coffee, slower pull), or the distribution (better distribution, less channelling).
Step 1: grind 18 - 21 grams of coffee, finely
Step 2: dose and distribute evenly into portafilter
Step 3: tamp evenly and with at least 30lbs of pressure
Step 4: flush grouphead of water for <1 second
Step 5: lock portafilter into grouphead
Step 6: start pull, keeping an eye on time and weight or volume yield
Step 7: watch for signs of channeling during pull (very blonde-looking, spurts of liquid, non-even flow),improper distribution during dosing.
Step 8: when 25-30 seconds have elapsed, make sure the yield is still within range, 1.5-2oz
Step 9: taste and enjoy!