The word espresso is derived from the Italian word for express since espresso is made for and served immediately to the customer. An espresso is a 25-30 mls extract that is prepared from 7-9 grams of coffee through which purified water of 88-95°C has been forced at 9-10 atmospheres of pressure for a brew time of 22-28 seconds. The espresso should flow slowly out of the porta-filter/group handle like warm honey, have a deep reddish-brown color, and a crema that makes up 10-30% of the beverage. Espresso brewing is defined by four "M's": the Macinazione is the correct grinding of a coffee blend, Miscela is the coffee blend, Macchina is the espresso machine, and Mano is the skilled hand of the barista. When each factor of the four M's is precisely controlled, the espresso beverage that is produced is the ultimate coffee experience.
To define "espresso potential" as a measure of the perfection of an espresso. Ideally, espresso should be extraordinarily sweet, have a potent aroma, and flavor similar to freshly ground coffee. The crema would be dark reddish-brown. It would be smooth, yet thick. A perfect espresso would be enjoyable straight with no additives, yet bold enough to not disappear in milk. A pleasant and aromatic aftertaste would linger on the palate for several minutes after consumption.
Below are the various factors and problems with espresso that limit its potential and we describe how you can maximize the espresso potential. If any of these factors are off the espresso potential will be limited.
1. Blend - Without a good espresso blend you cannot have a good espresso. Coffees must be blended to achieve the sweetness, aromatics, and smoothness desired in espresso. The blend must also be fresh or at the very least, correctly stored.
2. Roast - Too often you will find espresso roasted very dark. This results in a bitter, charcoal tasting brew. People that know how to blend espresso will roast light to preserve the aroma and sugars.
3. Grind - The grind must be monitored to achieve an extraction time of 25-30 seconds. Do not change the pressure you tamp with to compensate for a grind that has become too large or small. More information on grinding.
4. Grinder - A high quality burr grinder is essential for espresso. A conical burr grinder is preferred to flat burrs since the particle size is more even, they last longer, and the coffee is not heated during the grinding process. If the burrs become hot the aroma of the coffee will be diminished. A conical/parallel hybrid blade is considered the best design by many coffee professionals.
5. Dosing - Coffee must be freshly ground to achieve peak flavors. Grind and dose on demand. When making an espresso grind only what is necessary for one shot, dose properly, tamp, and brew. Discard any espresso grounds that are not used within 30 seconds.
6. Distribution - Distribute the coffee evenly after dosing in the porta-filter before tamping.
7. Tamping - Tamp the coffee once very evenly with 2 kgs of pressure, then once with 15 kgs of pressure, and polish 720° (twisting the tamp on top of the coffee) with 10 kgs of pressure.
8. Water mineral content - The water used for espresso must be filtered. Some cities must even compensate for the mineral content of their water. Over time oxygen will be forced out of the water in the espresso machine leading to off tasting water. Try filling a small glass with water, letting it cool, and tasting it for off flavors. If the water tastes strange you may want to dump the tanks daily and begin with fresh water.
9. Water temperature - The water temperature should be stable and somewhere between 92-96°C. The choice of the espresso machine is very important to both water temperature and temperature stability.
10. Temperature stabilizing - A stable temperature means consistent espresso.
11. Water pressure - The pressure of the water forced through the espresso should be between 9 and 10 atm. This pressure is responsible for the development of the crema.
12. Boiler pressure - The boiler pressure determines the amount of water to be incorporated in the steam. If your milk is not foaming correctly as described in milk texturing you may want to experiment with different boiler pressures, but this should only be altered by professionals.
13. Extraction time - Extraction time to pour a single shot of Espresso (no more than 30mls) should be between 25-30 seconds. The goal is to have a dark red espresso take approximately 25-30 seconds to brew with no change in color.
14. Porta-filter/Group Handle and basket - The porta-filter should always remain the same temperature as the water used to brew the espresso. Therefore it should always remain in the group head.
15. Timeliness - Act quickly, but carefully. You should spend no longer than 30 seconds for the time it takes to dose, distribute, tamp, pre-heat, and brew the espresso. Another good tip to follow is never leave the coffee sitting in the group handle/portafilter for more than 3 seconds locked into the group head before starting the espresso process. This way you will reduce the chances of ever burning the coffee.
16. Espresso machine cleanliness - This is probably the biggest problem with espresso today. If the machine, basket, and porta-filter are not cleaned regularly the espresso will always taste rancid.
17. Espresso grinder maintenance - Everyday the burr blades should be cleaned. Between shots you may want to brush out the excess espresso that gets stuck between the burrs and the dosing chamber. The burrs must be replaced at least yearly so that they continue to produce coffee granules with a maximal surface area.
18. Environmental Factors - The humidity and temperature will change throughout the day. Since coffee is hydroscopic (absorbs moisture), the grind size can be changed to achieve a brew time of 25-30 seconds. The temperature will not affect the espresso like the humidity, but it is important to avoid exposing the coffee to any high temperatures until brewing.
19. Espresso cup - The espresso cup should be pre-heated prior to the espresso delivery. The espresso cup should have thick walls and a narrow mouth to retain heat and aroma, respectively.
20. Practice - The importance of practicing and experimenting can not be overstated. The key to espresso is to realize that it always has further potential. By changing any one of these factors you can improve or diminish its potential. Espresso preparation is an art that demands the precision and dedication of science. I have never achieved, nor have ever seen a perfect espresso. A perfect espresso more of a concept than an actuality. The beauty is that espresso is volatile and difficult. If it were easy we would develop a machine that can brew a perfect espresso every time. There are so many factors involved in espresso preparation that only a human mind and a passionate heart can begin to understand and control its complexity.
Extracting Espresso
The espresso is ready to be extracted after correctly roasting, blending, grinding, dosing, and tamping the coffee (See espresso potential).Before placing the porta-filter in the group head, allow 2 ounces (40mls) of water to flow through the head. This is called temperature stabilizing. Tightly place the porta-filter in place and place a pre-warmed glass below the spouts of the porta-filter. Use the manual switch to begin the pre-infusion cycle. This distributes water over the top of the espresso pellet to allow it to expand and seal properly before blasting it with pressurized water. For 1.5 ounces (30 mls) of espresso, the extraction should take between 23-30 seconds where the time starts when the espresso begins to flow from the spouts. 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 took longer than 30 seconds, adjust the grind to be larger in size. If it took less than 25 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.
