I suppose any primer on making espresso should start at the beginning with the question – “what is espresso?” The question seems like it should be uncontroversial and easy to answer, but like anything it does have shades of grey.
Before we go technical let’s go for the simplified version. A beginner should try to produce 2 ounces of espresso from 16 grams of coffee in around 25 seconds and then change the parameters from there to taste. If the tamp is consistent and the dose is consistent you should grind finer if the coffee comes out too fast and coarser if the coffee comes out too slowly. These are not hard and fast rules, but they are great targets to start out with.
Now to those pesky definitions…
Here is the SCAA’s definition of espresso…
“Espresso is a 45ml (1.5 ounces) beverage that is prepared from 7-9 grams of coffee through which clean water of 192 - 198 degrees F has been forced at 9-10 atmospheres of pressure, where the grind of the coffee has made the brewing "flow" time approximately 22-28 seconds. While brewing, the flow of Espresso will appear to have the viscosity of warm honey and the resulting beverage will exhibit a thick dark gold cream foam ("crema") topping. Espresso is usually prepared specifically for, and immediately served to its intended consumer.”
In truth Espresso in America is not usually made this way. Americans both at home and in coffee shops almost always make doubles. The traditional double is made from 14 grams of coffee again pulled between 192 degrees and 205 degrees and producing roughly 2 ounces of liquid in 22-28 seconds. Many of the top coffee shops increase the dose up to as much as 22 grams of coffee. The average double shot is probably produced from 16-17 grams.
One problem with this definition still is that crema is bubbly and so it is hard to use volume to measure the quantity of coffee produced. A better idea is to use weight. A reasonable objective might be for a standard double shot to start with 14-18 grams of espresso and to produce roughly twice as many grams of espresso. For a ristretto one might aim for the same starting weight and producing one to one and a half times as much espresso.
For a more technical analysis of the idea of brew ratios (comparing the weight of beans to weight of liquid see
For an Italian perspective on why American’s are doing espresso wrong see
Then again this was written by a barista who finished way behind the Americans who were “messing it up” at the World Barista Championships so I would take his comments with a grain of salt.
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