Espresso is a brewing method that utilizes extremely high-pressure water (9 bars of pressure, equivalent to a fire hydrant) coupled with a fine grind to yield a small (classically 1.0 – 1.5 ounces) but thoroughly complex and flavorful extraction. Espresso requires the most precision of any brew method, as any number of variables can drastically affect a given shot – grind setting, dose, extraction time, temperature, extraction yield, roast date of the coffee, and even barometric pressure of the air, to name a few – and will often require small, but critical adjustments to optimize taste. It will take time, trial and error, and the development of your palate in order to build an intuitive understanding of espresso technique. The following instructions are merely guidelines for making espresso; they are hardly the rules.
STEP 1: Grind out your desired dose (on any given day, 18.0 g – 19.0g works best for Quantum Espresso) into a clean, bone-dry portafilter. A kitchen scale that measures to 1/10th of a gram is enormously helpful here.
STEP 2: Using the middle of your index finger, gently “groom” your espresso with a North-South-East-West motion, evenly distributing the grounds to all parts of the portafilter basket. A flat, even distribution is absolutely crucial, as water takes the path of least resistance through the basket. If there are holes, gaps, or inconsistencies in the distribution, the water will flow more freely through these areas and extract them too quickly, pulling out more undesirable bitter components from these areas over the course of the extraction. This is known as “channeling”.
STEP 3: Position the portafilter on a flat, level surface, like a counter-top or a tamp bar. With a neutral wrist, gently bring down a dry tamper perpendicular to the portafilter and rest it on top of the espresso. Hold the handle of the tamper between your thumb and forefinger (like a doorknob) and with one motion push down and apply ample pressure to all parts of the espresso equally. If properly executed, your tamp will create a perfectly flat seal and an equal path of resistance for the water. If your tamp is slightly askew or crooked, DO NOT try to tamp the espresso a second time. This will likely crack the seal under the surface of the espresso and cause severe channeling.
STEP 4: Lock your portafilter into the grouphead of the espresso machine and turn on the water. Place a small vessel under the portafilter; a ceramic demitasse is ideal, as its shape and small surface area help preserve aromatics and temperature. Pay careful attention the way the liquid flows out of the portafilter. If water sprays out of the portafilter rapidly or erratically, your grind is likely too coarse or your dose is too low. If it dribbles out of the portafilter in small, oily drops, your grind is likely too fine or your dose is too high. Ideally, the espresso will begin flowing smoothly out of the portafilter after a few seconds, pulling at a steady rate from the center over the course of the extraction. Towards the end of the extraction, you’ll notice a gradual thinning, flickering, and/or yellowing of the stream, at which point it is time to stop the flow of water and cut the shot.
Generally speaking, a 30g shot extracted over 25-29 seconds will offer the best results. However, your palate is the ultimate assessor of quality, and sometimes smaller/larger volume extractions over shorter/longer total extraction times may yield the optimal experience. We encourage experimentation and above all else, calibrating your shots to taste.