The best espresso should be extraordinarily sweet, have a potent aroma, and flavor similar to freshly ground coffee. The crema should be dark reddish-brown and smooth, yet thick. A perfect espresso should be enjoyable straight with no additives, yet bold enough to not disappear in milk. A pleasant and aromatic aftertaste should linger on the palate for several minutes after consumption.
The following steps describe in detail how to make espresso. You will also learn about the various factors and problems with espresso that limit its perfection. If any of these factors are off, you will not achieve a high quality espresso.
Making Perfect Espresso
Without a good espresso coffee blend you cannot have a good espresso. The best espresso coffee beans are blended to achieve the sweetness, aromatics, and smoothness desired in espresso. The espresso blend must also be fresh. We recommend using espresso within four days of roasting. Please see the espresso blending section for help on creating your own blends or order some excellent espresso blends from roasted coffee suppliers, such as Caffe D'arte or Espresso Vivace.
Too often you will find espresso roasted very dark. This results in a bitter, charcoal tasting brew. People that know how to make an espresso will roast light to preserve the aroma and sugars. For more information, read the section about espresso roasting.
The grind must be continuously monitored throughout the day 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. For more information, read the section about espresso grinding.
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 coffee aroma will be diminished. A conical/parallel hybrid blade is considered the best design by many coffee professionals.
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. Discard any espresso grounds that are not used within 30 seconds. For more information, read the section about espresso grinding and dosing.
Distribution in Portafilter
Distribute the coffee evenly after dosing in the porta-filter before tamping.
Tamp the coffee once very evenly with 5 lbs of pressure, then once with 30 lbs of pressure, and polish 720° with 20 lbs of pressure. For more information, read the section about espresso tamping.
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.
The water temperature should be stable and somewhere between 92-96°C. Choosing the best espresso machine is very important to both water temperature and temperature stability.
A stable temperature helps ensure that you prepare excellent espresso. For more information about stabilizing the temperature of your espresso machine, read about espresso temperature stabilizing.
Water pressure for Espresso
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.
The boiler pressure determines the amount of water to be incorporated in the steam. If your milk is not foaming correctly as described in the section on latte art, you may want to experiment with different boiler pressures. Boiler pressure, however, 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 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 25-30 seconds to brew with no change in color. Fore more information, read the section on extracting espresso.
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.
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.
Espresso machine cleanliness
Coffee machine cleaning 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.
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.
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 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.
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.
Practice makes perfect
If you want to learn to make espresso, it is essential to practice and experiment. The key to making 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 anyone make a perfect espresso. A perfect espresso is 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 knows how to make 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.
A manual piston espresso machine
Since their invention in 1901 multiple machine designs have been created to produce espresso. Several machines share some common elements. The portafilter (or group handle) contains a metal filter-basket and holds the ground coffee. It is locked under the group head's diffusion block.
Varying the fineness of the grind, the amount of pressure used to tamp the grinds, or the pump pressure itself can be used to vary the taste of the espresso. Some baristas pull espresso shots directly right into a pre-heated demitasse cup or shot glass, to maintain a higher temperature of the espresso.
An espresso machine may also have a steam wand which is used to steam and froth milk for beverages such as the cappuccino and latte.
A steam-driven unit operates by forcing water through the coffee by using steam or steam pressure. The first espresso machines were steam types, produced when a common boiler was piped to four group heads so that multiple types of coffee could be made at the same time. The design is still used today in low-cost consumer machines, as it does not need to contain moving parts. Many low-cost steam-driven units are sold in combination with a drip-coffee machine.
The piston, or lever, driven machine was developed in Italy in 1945 by Achille Gaggia, founder of espresso machine manufacturer Gaggia. The design generically uses a lever, pumped by the operator, to pressurize hot water and send it through the coffee grinds. The act of producing a shot of espresso is colloquially termed pulling a shot, because these lever-style espresso machines required pulling a long handle to produce a shot.
There are two types of lever machines; manual piston and spring piston design. With the manual piston, the operator directly pushes the water through the grounds. In the spring piston design, the operator works to tension a spring, which then delivers the pressure for the espresso (usually 8 to 10 bar).
A refinement of the piston machine is the pump-driven machine, which has become the most popular design in commercial espresso bars. Instead of using manual force, a motor-driven pump provides the force necessary for espresso brewing. Commercial or some high-end home machines are often attached directly to the plumbing of the site; lower-end home machines have built-in water reservoirs.
Some home pump espresso machines typically use a single chamber both for heating water to brewing temperature, and to boil water for steaming milk. Since the temperature for brewing coffee is sometimes less than the temperature for creating steam, the machine requires time to make the transition from one mode to the other. Commercial-grade and "semi-commercial" high end home espresso machines use the boiler chamber only for making steam. Water for brewing most commonly passes through a heat exchanger (taking some heat from the steam, without rising to the same temperature). In a few commercial espresso machines (notably La Marzocco), water for brewing is heated in a separate chamber.
Machines which contain the addition of pumps, sensors, valves, and grinders to automate the brewing process generally are referred to as automatic.
- Semi-automatic machines are automatic in the sense water is delivered by a pump, rather than manual force and remaining brew pressure in the basket is dissipated with a three way valve.
- Automatic machines add a flowmeter inline with the grouphead. When the programmed amount of water has flowed through the flowmeter, the pump is automatically turned off and brew pressure released through a three way solenoid valve.
- Super-automatic machines operate by automatically grinding the coffee, tamping it, and extracting; all an operator needs to do is fill the bean hopper, and if the machine is not connected to a water line, add water to a reservoir. Additionally, models contain an automated milk frothing and dispensing device.
Quite possibly the most important step in buying a good espresso machine is getting a good grinder to match up to it. A quality grinder is crucial to good espresso.
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. Instead of two pulls on the doser, the barista should pull several times until the entire basket is filled with ground coffee.