How to Make a Good Espresso
By Josh Kemper
July 11, 2009
What Is Espresso?
Espresso (please stop saying "expresso") is the essence of coffee. It is a highly-concentrated brew of coffee having bold flavor, and a heavy (ideally creamy) body. A standard shot of espresso is about 1 to 1.5 ounces. Good espresso has good crema. If there is no crema it is not espresso, but only strongly brewed coffee. The crema in a good espresso serves the purpose of adding a creamy body, and more importantly, trapping the sweet gasses (only found in freshly roasted coffee) and delivering them to your olfactory. Making good espresso requires adequate equipment (which can be pricey), freshly roasted and properly blended coffee and proper technique. Bringing out all the flavor of the coffee without making a bitter brew requires fully extracting the coffee without over-extracting the coffee. This requires some amount of skill. Most people who do this professionally (baristas) still can’t do this well, even though they are paid to.
Machines
The Espresso Machine: The brewing of espresso is not simply hot water passing though ground coffee, but there must be a precise balance pressure and temperature. Temperature is the easiest factor to get right, though not the cheapest. Though espresso machines come from the factory supposedly set to heat water to a proper brewing temperature, most low-end espresso machines (what you might buy at Walmart) do not have an adjustable temperature. Most others do, but the adjustment is difficult guesswork. Only a few machines (so far) can accurately control water temperature while giving you full manual control. Synesso is the best and most expensive. But for those who can only dream of having a several-thousand dollar machine, the best option is a small machine with a PID upgrade. A Rancilio Silvia with a PID installed can produce some of the best espresso possible. Other models can be upgraded with PID systems as well. Temperature is not the only factor to consider when choosing an espresso machine. Temperature control is not the best feature of the La Pavoni Europiccola, but it is still a great machine to have. What you do have full manual control of with this machine is the pressure. You use a lever to push a piston though a cylinder at great pressures, potentially much greater than what an electric pump can do. The machines that simply use steam pressure to push water through the coffee grinds can not produce a good espresso. The pressure and temperature are much too unstable, so even if a good shot does happen (not likely) it will definitely not happen consistently.
The Coffee Grinder: Particle size has a huge impact on brewing espresso. If you imagine a pile of rocks, a pile of gravel and a pile of fine sand, and then imagine how quickly water would pass through each, it gives you a good visual to understand how particle size effects brewing. Obviously smaller particles, having more surface area, slow the flow of liquid. A fine powder will not let water just pour through, especially if packed down tightly; and the only way liquids can find their way though in a short time is if they are forced through with pressure. As hot water is forced through properly ground coffee the oils, carbohydrates, and gasses emulsify in the water, and the gasses are trapped in very small (nearly microscopic) bubbles of which the crema consists. If the coffee is not ground to a very precise and uniform particle size, a good crema is not possible. This is why having a good conical burr grinder is just as important as having a good espresso machine. Examples of excellent grinders are the Mazzer Mini, or the Rancilio Rocky. Examples of adequate grinders are Cuisinart conical burr grinders, or the KitchenAid Pro Line grinder. You also need to consider whether or not you want your grinder to come equipped with a doser. A doser is used to distribute a consistent dose of ground coffee. It can usually be adjusted so that every “pull” gives the amount you set it to give. Most espresso experts recommend using a doserless conical burr grinder such as the doserless Rocky, because the coffee will not only be properly ground, but properly distributed directly into the portafilter. Another thing to consider when buying a grinder is the weight of the grinder. A sturdy grinder such as the Rocky does not kick around when grinding a light roast coffee, but some grinders cannot grind a lighter roast properly because there is not enough weight behind the burrs and lighter roasted coffee beans are much denser and stronger than darkly roasted coffee beans. If you are only using medium-dark to dark roast espresso blends, this is not much of an issue.
Coffee
First off, there is no such thing as the “espresso roast” or “espresso beans”. Espresso beans are just a blend of regular coffee beans. There is a huge diversity of coffee beans, most of which can be used in espresso. There is also a wide range of roasts. An espresso blend can consist of all kinds of coffees and roasts. It’s all a matter of taste. The two most common types of espresso blends are the west coast style, which is typically a blend of higher acid coffees at a darker roast, and the European style, which is typically a heavy bodied, low-acid blend of beans at a medium-light roast. While the west coast blends are much more popular throughout America, the European style blends are more respectable according to professional standards. For example, a typical espresso such as the espresso served at Starbucks would score very low at an SCAA espresso competition, though it is what the masses drink. Choosing coffees to use in an espresso blend requires a huge amount of knowledge and experience. There are hundreds of coffees, and one must know what each kind of coffee will do to the blend. The basic characteristics of coffee are acidity and body. Besides knowing what kind of acidity and body the coffees have, it is also important to know what kind of flavors the coffees have. Some examples of coffees that are commonly used to make low-acid espresso blends are Brazilians such as Cerrado and Sul de Minas, Indonesians such as Sumatra, Papua New Guinea, and Celebes, and lower acid El Salvador and Peru. Acid is not always a bad thing is espresso blends as it can add really good flavor to espresso. Some low acid, heavy bodied espresso blends can have great crema and have perfect basic characteristics but be a little dull in flavor. This is when adding a little bit of a flavorful higher acid coffee can make your espresso come to life. Harrar, Guatemala, Zimbabwe, and Nicaragua can serve such a purpose, as well as many others, depending on what kind of flavor you want to add to your blend, only care must be given not to ruin the crema when doing so. When only the origin of the coffee is given and not the species, it is assumed the coffee is Arabica. If a Robusta is from Guatemalan it will typically be called “Guatemalan Robusta”. The difference between Robusta and Arabica is great. Arabica is more acidic, sweeter and has a cleaner flavor. Since Robusta has a very heavy body, and a low acidity, it can make a heavier, creamier espresso blend with an impressive crema, even when added in at as little as 10%. The main detriment to Robusta is the “dirty” taste it has, which some people really don’t prefer. It is very common in Europe though, and some people really enjoy the flavor, especially if they discovered their love for coffee in Europe. Some people consider Robusta to be the “Cinderella of coffees”. The Robusta market is quickly changing and new high-quality Robusta are being produced every year. A good washed Robusta can add a lot to an espresso blend without ruining the flavor, even for people who do not enjoy the taste of a regular Robusta. Some people blend their coffees together before roasting. This is called a “pre-roast blend”. Others blend their coffees after they are all roasted separately. This is called a “post-roast blend”. A pre-roast blend melds the flavors together, but can be difficult to do right, because all of the beans in the blend must be able to work well together at the same roast profile. Some beans roast different than others, so it doesn’t always work. A post-roast blend allows the roaster to use different beans at different roasts. One method is not better than the other; it is a matter of preference.
Technique
After obtaining the right equipment and a good espresso blend, the only thing missing is a skilled hand. The tasks that are controlled by hand are getting the coffee into the portafilter and topping off and leveling out the ground coffee so that it is evenly placed in the filter, and then properly tamping the ground coffee. “Tamping” is using a tamper to compact the coffee so that the hot water does not pass through too quickly, but also does not have too much resistance and take too long. If the coffee is more tightly packed in one part of the portafilter, the water will tend to go around that area. It will take the path of least reisistance. If the water flows through one area more, the coffee in that area will be overextracted and the coffee in other areas will be underextracted, so it is important that the coffee is distributed and tamped as evenly as possible. The coffee must be ground, dosed and tamped in such a way that the coffee in general is fully extracted, but not overextracted. The most common way to find the right balance of grind, dose and tamp is to start out at a very fine grind, filling the portafilter to the rim and gently leveling the top without compacting the grinds, and then using a tamp of 30 pounds pressure. A metal bar key can be used to level the coffee or it can be done by hand. Obviously using a metal bar key looks more sanitary to customers, and also seems to be more precise, but many of the best baristas actually prefer to use their fingers. A good extraction time for a lighter roast blend is 30 seconds to fill two standard 1.5 ounce shot glasses. If it takes longer, make the grind slightly coarser and visa versa. Lighter roasted coffee extracts slowly and darker roasted coffee extracts quickly. So the tamp, grind and brewing temperature should be set custom for your blend. Dark-roast coffee tends to break up easier and turns to a fine powder more easily than light-roast, so even if you are using the same setting on your grinder, a dark roast will tend to be finer, so you need to adjust so that you don’t clog the portafilter. It will probably take several experimental shots that should probably just be tossed in order to find the right balance of grind and tamp. Once your espresso is pulling between 20-30 seconds, try experimenting with longer or shorter shots to see if it needs more or less extraction. The more you work with your espresso, the more you will discover just how you like it and you will find that even though it is messy work, the fun is in seeking out the process and experience coffeegeeks call “espresso Nirvana”.