From Espresso Bean to Espresso by Doug Morse

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Espresso Preparation

Espresso is ready to be extracted after correctly roasting, blending, grinding, dosing, and tamping the coffee. You have just purchased highly-quality espresso beans that cover the roasting and blending. To make the most of these beans, keep reading to learn how to properly grind, dose, tamp, and finally extract espresso that brings out the full and natural flavor inherent in the beans, without any bitterness or astringency. You will also learn a bit about why proper execution of these steps is important, as well as how to monitor and improve the process if there are any problems.

Grinding

To extract espresso properly it is essential to use an espresso burr grinder and to grind per order. The two major types of burrs used are flat and conical. Conical burr coffee grinders are desirable because they increase the surface area of each particle and the amount of flavor that can be extracted from the coffee. Since a conical burr grinder has longer cutting edges, the burrs can rotate at lower speeds, which reduces the heat created. Flat burrs should be replaced after 600 pounds of coffee have been ground and conical burrs should be replaced after 2000 pounds of coffee have been ground.

Coffee is freshest immediately after it is ground. After grinding coffee beans, the volatile oils that were previously protected inside the bean are exposed to the air which oxidizes and stales the coffee. This effect occurs immediately after coffee grinding so it is important to tamp and extract the espresso as quickly as possible. The coffee grinder should be activated for 15-20 seconds every time a shot is desired so that only freshly ground coffee is used.

Espresso coffee should be ground to a size in which the extraction process takes 23-28 seconds. It is important to only adjust the grind and not the pressure one tamps with to control the flow rate. In addition to particle size, the humidity plays a dramatic role on extraction time. Since coffee is hydroscopic, it absorbs moisture from the air causing a tighter pack and longer extraction time. Thus, the grind setting should be adjusted slightly throughout the day to ensure the extraction time remains correct.

A very fine grind is highly recommended to ensure quality taste. Ideally, about 20% of grinds are fully extracted. Determining which fineness setting to use is a matter of trial and error, and depends on the particular burr grinder, the type of beans, the freshness of the beans, the humidity, and other factors.

a) Only grind the beans immediately before extraction, using a quality burr grinder

b) Adjust the fineness of the grind, not the tamping, to ensure a 23-28 second extraction time and that 20% of the grinds are fully extracted

Dosing

The median dose for a single espresso shot is 1 ounce (30 ml) and this amount is often recommended. However, people have different preferences for the taste and thickness of their espresso, so adjustments to taste are perfectly appropriate. For example, some people prefer their shots ¿ristretto,¿ which is about ¾ of an ounce. Others prefer shots from 1 ¼ to 1 ½ of an ounce.

Use between 7-9 grams of grinds for a single shot, between 14-18 grams of grinds for a double shot.

To make quality espresso consistently, the temperature of the water inside the espresso machine should remain relatively constant. Temperature stabilizing is a method used to help maintain the water inside your espresso machine at a constant temperature, and should be ensured for each shot. If you have an espresso machine that supports a pre-infusion cycle, place your grinds in the portafilter, tamp them (see next), and follow the pre-infusion cycle procedure.

If your machine does not support a pre-infusion cycle - most consumer models do not - then you can achieve temperature stabilization with the following steps: (a) place the empty portafilter in the machine, (b) place a pre-warmed, empty glass underneath the portafilter, (c) allow 2 ounces of heated water to flow through the head and the portafilter, (d) remove the portafilter, shake away any residual hot water into a nearby sink, and wipe the inside of the portafilter dry, (e) add your grinds to the portafilter, tamp them (see next), and place the portafilter back in the head. Obviously, exercise caution when following these steps so as not to burn yourself or others.

a) Dose according to taste and shot size

b) Practice temperature stabilization to ensure consistent, quality espresso extraction

Tamping

Tamping is the compacting of the ground coffee in the portafilter prior to brewing. How one tamps will be a major determinant to the quality of the espresso, because compacting the coffee firmly and uniformly forces the water to flow through the grounds in a manner that extracts the best of the coffee's flavors. Unfortunately, improper tamping method are common. Some people have heard that firm tamping is important, but really do not understand the mechanics involved, which is important.

Tamping is necessary because the brew water is under intense pressure (8 to 10 times the weight of gravity) and will have an almost intelligent ability to find the paths of least resistance through the coffee. If it does find channels that are easy to get through it will rush through these areas, overextracting the coffee surrounding the channels and underextracting the coffee grinds elsewhere. The resulting beverage is the worst of circumstances: What flavor does get into the cup is bitter and astringent, and so much of the coffee's potential good flavors remain behind in the portafilter basket. With firm and even tamping, the water has no choice but to flow through all of the coffee uniformly, and if the grinds are correct and the espresso machine is in good order, the resulting beverage represents the best the espresso beans have to offer.

Thus, to tamp correctly, follow the following steps:

Step 1: Having dosed the proper amount of coffee into the portafilter basket, even it out so that it is level in its distribution in the basket. Any ¿high¿ points will result in areas more compacted than ¿low¿ points after tamping, so it is important that the coffee be packed full and level in the basket.

Step 2: Use a flat-faced hand tamper and a counter that is low enough so that you can lean into the tamper with your body weight and arm straight. The tamper should be held in your relaxed hand as an extension of the arm. The tamper face needs to always be applied straight into the coffee, without an angle, because any canting will result in an area where the coffee is thinner.

Step 3: Note that the diameter of the tamper is slightly smaller than the inside diameter of the basket. If you just tamp in the middle, the outside perimeter will still be loose, exaggerating the tendency for the water to flow between the basket and the coffee. Thus, the ¿Staub Tamp¿ is recommended, where you tamp the coffee four times riding the tamper up against the inside of the ¿North, South, East, and West¿ edges of the basket. Tamp with 30-40 pounds of pressure (trainers sometimes have trainees tamp on a bathroom scale on the counter for practice). This evenly compacts all of the coffee giving the water a uniform bed to percolate through. Do not tap the portafilter handle between tamps, as this will just tend to loosen adhesion between the packed coffee and the basket. When releasing pressure from each of the four tamps, give a slight twist to the tamper to polish the surface of the compacted coffee.

Step 4: Inspect the result of your tamping to make sure that it was even and there is a good polish. If you notice that one side is deeper than another, you should knock out the grounds and start over again. If everything looks acceptable, then mount the portafilter handle into the espresso machine's group head and begin the brewing cycle.

Step 5: The final step in tamping is quality control assessment. Noting the quality and taste of the extraction is critical to improving your tamping skill. Also examine the spent coffee in the basket after brewing and look for ¿worm holes,¿ which is a sure sign of channeling where the water found a weak spot in the coffee pack. The knocked out grounds should have the form of a puck; if they are more like mush, then the grind and tamp were off. Tamp 4 times with 30-40 pounds of pressure, with a polish twist after each, as described above. Monitor your results by inspecting the grinds after extraction for any signs of uneven flow (e.g., worm holes, or mush)

Extracting

As noted, the extraction should take between 23-28 seconds after the espresso begins to flow from the spouts. To prepare excellent espresso, the pour should look like warm honey dripping from the spouts. Manually stop the extraction if the espresso turns a slight shade lighter in color. If it takes longer than 28 seconds, adjust the grind to be larger in size. If it takes less than 23 seconds, adjust the grind to be smaller. Do not vary the pressure you apply in tamping since you only want to adjust one variable at a time. By adjusting the tamping pressure you are simultaneously adjusting several parameters that will often result in an undesirable product even if you do attain the right timing.

The water temperature should be anywhere from 195-200 degrees F. The water pressure should be between 8-10 bars (generating 140 pounds per square inch), although some people set their machine to slightly lower levels to minimize the extraction of any unpleasant oils.

Properly extracted espresso should yield an aromatic crema. The first drops from the machine should be crema, not a dark liquid. More drops of crema should follow the first drops and within two to four seconds of the first drop there should see a steady flow of crema. This flow should be consistent and continuous in both speed and in volume. The width of the flow should never be wider than one-eighth of an inch. The speed of the flow should be constant all the way through the espresso extraction (i.e., it should not speed up as the volume of espresso extracted increases). The color of the crema should be medium brown. As it flows, it should not be yellow, white, or tan to white. The flow should not have a lot of air bubbles, and should be as viscous as possible. As the crema flow starts layering itself, it should not disintegrate or separate. It should simply remain a syrupy consistency, and should begin layering. At the finish, the best crema is uniform in presentation: an even, homogeneous layer of color and texture.

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