Espresso Preparation

The word espresso is derived from the Italian word for express since espresso is made for and served immediately to the customer. (Or as I like to think “to be made especially for”.) A double espresso is a 47-62.5 ml (1.5-2 ounce) extract that is prepared from 14-17 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 to 28 seconds. The espresso should drip out of the porta-filter 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":

1. Macinazione is the correct grinding of a coffee blend.
2. Miscela is the coffee blend.
3. Macchina is the espresso machine.
4. 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.

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.

Here are the various factors and problems with espresso that limit its potential.

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.

Roast - Too often you will find espresso roasted very dark. This results in a bitter, charcoal tasting brew. I find that this is the general trend on the West Coast of the United States, The Northern Italian style espresso blend is roasted lighter to preserve the aroma and sugars.

Grind - The grind must be continuously monitored throughout the day to achieve an extraction time of 20-27 seconds. Do not change the pressure you tamp with to compensate for a grind that has become too large or small.

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 taste of the coffee will be diminished.

Dosing - Coffee must be freshly ground to achieve peak flavors. Grind and dose on demand. When someone orders an espresso grind only what is necessary for one shot, dose properly, tamp, and brew.

Distribution - Distribute the coffee evenly after dosing in the porta-filter before tamping.

Tamping - Tamp the coffee once very evenly with 5 lbs of pressure, then once with 30 lbs. of pressure, and polish 720° with 15 lbs of pressure. Make sure that the tamp is even, an uneven tamp will produce an over extracted pull.

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.

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.

Boiler pressure - The boiler pressure determines the amount of water to be incorporated in the steam. If your milk is not foaming correctly you may want to experiment with different boiler pressures, this should only be altered by professionals. You can check your boiler pressure by looking at the boiler pressure gauge on the front of most espresso machines.

Extraction time - Extraction time to fill two 1-oz cups should be between 25-30 seconds. Despite the time the pump should be turned off if the espresso becomes slightly lighter in color. The goal is to have a dark red espresso take approximately 20-27 seconds to brew with no change in color.

Porta-filter 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. The basket should hold 16-18 grams of coffee and must be straight walled. Curvatures in the basket will lead to uneven extraction.

Espresso machine cleanliness - This is probably the biggest problem with espresso today. If the machine, basket, and porta-filter are not cleaned at regular intervals the espresso will always taste rancid.

Espresso grinder maintenance - Everyday the burr blades should be swept clean. 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.

Environmental Factors - The humidity and temperature will change throughout the day. Since coffee is hydroscopic (absorbs moisture), the grind size must be changed throughout the day to achieve a brew time of 20-27 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.

Espresso cup - The espresso cup should be pre-heated from a source other than the espresso machine. Filling a cup with water from the espresso machine prior to brewing the espresso will lower the temperature of the water in the boiler and the espresso extraction will be uneven. The espresso cup should have thick walls and a narrow mouth to retain heat and aroma, respectively.