An espresso recipe is the ratio of dose to yield. The dose is simply how much coffee you put in the portafilter. The yield is the amount of espresso (liquid) you get out. We recommend starting with a recipe of 1 part coffee to 2 parts espresso. Your dose will be determined by the size of your portafilter and how much espresso you desire to make. A typical recipe at our cafe is19 grams of coffee to 38 grams of espresso.
Shot time is the length of time from the moment you engage the machine to when your espresso shot has reached your desired yield. If your shot time is too short, your coffee may be sour and lack sweetness. If your shot time is too long, the espresso may be astringent or overly bitter. Every coffee is a little different, but in general, we recommend a shot time between 25-30 seconds.
Grind size is the main variable that we use to control shot times. The finer you grind your coffee, the slower the water will flow through the grounds, resulting in a longer shot time and increased extraction. Espresso requires a grinder that can produce fine grinds and is capable of making micro-adjustments to the grind size. We feel that a quality grinder is the single best investment you can make in your home espresso setup.
How you distribute and tamp your coffee will have a significant impact on how your espresso extracts. Remember that water will always take the path of least resistance. Water will flow through sections of your puck (the bed of grounds in the portafilter) that are the least dense, extracting more from this area and less from the denser sections of the puck. It is therefore important to distribute the grounds evenly around the portafilter and make sure that your tamp is level to ensure that water is flowing equally through all portions of the coffee bed.