Espresso: The Art of Coffee

Espresso can be considered coffee incarnate. Using extremely hot water and very high pressure, espresso forces water through coffee grounds to extract all the caffeine, flavors, and oils. All types of specialty coffee require an espresso shot in some form or another. There is a slim margin for error when it comes to espresso, with good coffee transforming into horrible coffee at the drop of a hat. With so many components to account for when it comes to espresso, it has transformed into a serious art form.

Evolution of the Espresso:

Espresso has been around for a long time. It was first developed by the Italians in the mid 1800's, but espresso really didn't take hold until it changed a fundamental part of the brewing method. Originally, espresso was extracted using steam pressure. Using an elaborate system of tubes and fluid dynamics, this method relied heavily on the weight of the hot water(steam) to apply the pressure to the grounds. While there was significant pressure applied to the grounds, it was not adequate to push the water through the grinds effectively. The water took too long to get through the grinds, resulting in coffee that tasted sour and bitter. If there was some way to speed up the water and keep the temperature regulated, the coffee could be effectively extracted.

In the early 1900's, the introduction of the piston-driven espresso machine drastically changed the way people made espresso. Using a manual lever, baristas were able to apply the hot water over the grounds at very high pressures. Combined with a very fine grind of coffee, a single shot of espresso could be extracted in a few seconds. With this new type of extraction, a golden foam was produced that floated on top of the shot. Once thought to be a waste product, crema is now understood to be the pinnacle of the espresso shot.

Though the piston was a huge breakthrough in the industry, it still had some design flaws. Since it was a manual lever, it required some strength to apply the pressure. Even more so, since a person was the main force behind the piston, shots would come out uneven due to the varying degree of strength applied. Designers were looking for a way to keep a consistent level of pressure and produce a shot that had little varying degree of quality. Using a spring powered piston, Italian designers eliminated many of the problems with manual piston-driven machines. With the spring substituted for the manual lever, the piston was now able to provide pressure that didn't rely on the applied strength of the barista. While shots could be extracted with more precision, it still had some drawbacks. The spring coil eventually loses its strength and would need to be replaced from time to time to ensure precision.

The last great breakthrough in espresso is the pump driven espresso machines. Replacing the use of spring-powered force, a motor pump is used to apply the pressure to the grounds. This eliminated the constant replacement of springs. Pump espressos have become the standard in most commercial espresso bars and coffee houses. Most of the home espresso machines are also pump driven though they are not as complex as the commercial ones.