Overview of Espresso and Espresso Machines

What do you think of when you hear the word "espresso"? Perhaps,

"Express - train; fast black, iron horse of rocket fuel!"

Or,

"Strong. Hyper-caffeinated. Bitter. What, me try it?" (is you a man or is you a mouse?)

Also, maybe,

"I like my coffee black, but not that black!"

Wrong. Espresso, when correctly made, is none of these things.

Espresso is a traditional coffee drink invented by the French, but perfected by the Italians. You can associate the word "espresso" with the English word "press", for that is the fundamental action pertaining to both the ground coffee - which is pressed into a compact disc - and the machine used to make it, which forces or "presses" hot water through the disc of coffee. The result is a demitasse (very small cup) of all of the best characteristics of the coffee bean with none of the less desirable ones.

A well "pulled" shot of espresso is not bitter. The flavor is full, complex, and remains on the tongue for 10-15 minutes after drinking it. That flavor can be fairly accurately compared with the wonderful aroma present when the seal is first broken on a container of coffee. If your espresso is bitter blame the barista, not the drink.

Afraid of the shakes? Don't be. Surprisingly, given the concentrated nature of the drink, a shot of espresso has only about half the caffeine of a normally brewed cup of joe. This is because the heated water is forced through the coffee too quickly (ideally in around 20 seconds) to liberate all of the caffeine present in the grind.

All of this wonderfulness requires a special type of machine to make. As already mentioned, an espresso machine's express purpose is to press heated water (about 200 degrees) through a disc of pressed coffee. How is this accomplished? There are 3 basic designs: steam driven, piston driven, and pump driven.

Mechanically, the simplest is the steam driven machine. It employs steam pressure to force water through the coffee. Since there are no moving parts, this design is normally used for lower-priced home espresso makers. This principle was also used in early commercial machines but was abandoned by professionals when a better design came along in 1945.

That design is the piston driven machine. In this design, a long lever is pulled by the barista (hence the phrase "pulling" a shot) to drive a piston, which in turn forces the heated water out of a cylinder and through the coffee. A later refinement of this design was to interject a spring into the process between the lever and piston. The lever compresses the spring, which in turn drives the pistion. The purpose is to better control the pressure of the water (ideally 9 ft-lbs) as it is forced through the coffee.

An even better design was introduced in 1961, the pump driven machine. This design uses an electric pump to force the water. The benefit is more accuracy (and no arm-strain!).

Good espresso also has a "head", like a beer does. The head is made up of concentrated oils from the coffee. It is dark reddish-brown, and should have enough body to support the weight of a teaspoon of sugar for about 2 seconds before it sinks into the drink.

The coffee itself is, of course, rather important. It should be of a medium roast; a dark roast has had too many of the oils and sugars cooked out of it. It also needs to be ground exactly right. A proper grind can be described as the consistency of talcum powder. The best bet is to have your espresso professionally ground at a good shop. They have the right equipment and know-how to make a perfect grind.

Need water quality even be discussed here? You don't drink tap, so don't brew tap. Enough said there.

Espresso is complex in both nature and process. It requires special equipment and exacting technique to make properly, but is well worth the effort. If you've never tried it, drop by a reputable coffee house and let them convince you. Chances are you'll be hooked.