Barista Technique:
Diagnosis of Extraction Problems

Espresso is mostly defined in terms of shot time and volume, since these are easiest to measure. By convention, the volume specifications for espresso are total volume, combining crema and liquid. The dwell time, the time it takes from turning on the pump to seeing the first drops of espresso emerge from the basket varies from machine to machine. So by convention, espresso extraction times are specified from the moment the pump is turned on.

I will specify the diagnostics in terms of shot ending color and volume, since these have the most intuitive correspondence to espresso taste. This means you should end the shot at the specified color, and then set the grinder to get the specified volume.


Volume Terms:

Color Terms:

Special Terms:

Diagnosing the Taste and Appearance of an Extraction

Diagnostics means tasting the espresso and correcting its deficiencies by adjusting setup or extraction parameters. In a perfect world, correcting for one deficiency would never interfere with correcting for another. In the real world, there sometimes are conflicts, and you must prioritize. The highest priority goes to gross crema deficiencies, since these indicate that some parameter of the shot is well outside proper espresso range. The next priority is taste flaws that make a shot undrinkable. Finally, with these eliminated, you can work on fine-tuning everything to get the most harmonious taste.

Gross Crema Deficiencies

Gross deficiencies in the crema point to something far out of whack and have the highest correction priority. However, the blend itself may have unusually light, dark or thin crema; so when you notice these defects, taste the shot to confirm the problem.

Taste Flaws

These taste flaws ruin the shot. Correcting them takes precedence over working on the taste balance.

Unbalanced Taste

When the crema is right and the shot has no taste flaws, you can fine-tune the setup and extraction to provide the most harmonious and balanced taste possible. Although everyone wants balanced taste, the exact combination of sweet, bitter and sours tastes that any person considers balanced is extremely variable. So these adjustments will be subjective; and there may be more than one optimum set up for the blend, especially if it is complex in taste.

Pursuing the Godshot

If you've never tasted great espresso, you may have read the last section and asked yourself how you can do all the diagnostics. You have good taste, otherwise I can hardly imagine how you've read this far. Good espresso isn't a punch in the mouth, but tastes wonderful. Expect that, trust your taste and judgment, and make the adjustments accordingly. Then taste the results. You'll improve very quickly.

To further develop that taste, it greatly helps to sample top flight espresso and get a feel for all its possibilities. Take every opportunity to visit good cafés and roasters, and try their espresso and blends. Ask the coffee people there what you are tasting and how to tell if it's right. Don't worry about getting bad information—it's a lot easier to recognize a good coffee person than a good coffee because their enthusiasm gives them away.

Empty cup You can go further by drinking top flight estate coffees brewed regularly and learning how the coffees from different places in the world vary. In comparison to wine and other gourmet items, coffee is the most economical of the truly great taste experiences. Deepen your appreciation even further by home roasting you own coffees and blending them for espresso, or taking part at tastings conducted by roasters.

There is a large variety of espresso equipment, and it's useful to know something of the possibilities. These are discussed in great detail on the coffee Internet sites (see the resources and the rest of this site). If this interests you, participate in these discussions. There are frequent get-togethers that are organized via these sites, so you will also get some hands on experience.

Espresso is a social world. If you want to turn this into a serious hobby, join the Specialty Coffee Association of America (SCAA), attend conventions and barista competitions, get to know others like yourself, as well as the stars of the business. If you like espresso and coffee, I guarantee you'll enjoy the activity and like the people you meet.

Finally, coffee is a big global business. It encompasses large numbers of very poor farmers whose livelihoods are frequently in the balance, a few very big businesses buying from them cheap and cutting quality, a mass public that doesn't know much about coffee except that it's a pick-me-up, and a group of enthusiastic drinkers and purveyors who love coffee. As enthusiasts, it's incumbent on us to convey to others how rewarding good coffee can be. If we don't understand the coffee trade and its issues, and if we don't foster a wider appreciation of good coffee, many farmers will suffer, some of the world's great coffees may disappear, and we will all be the poorer for it.

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