Espresso is a technique for brewing coffee, and such, has a rich history rooted in chemistry and technology. In the late 19th Century, the steam age, European inventors were exploring ways to use steam to reduce brewing time. The invention of a machine and a technique that would lead to espresso is attributed to Angelo Moriondo of Turin, Italy, who was granted a patent in 1884 for “new steam machinery for the economic and instantaneous confection of coffee beverage.” Although,Moriondo's machine was the first to use both water and steam, it was a mass brewer created for the Turin General Exposition.
Luigi Bezzera was the owner of a manufacturing business who invented single shot espresso at the turn of the 20th century. He figured if he could just add more pressure to the brewing process it would speed things up. Thus the "Fast Coffee Machine" was created. Improving on Moriondo's technique, his invention introduced the portafilter and multiple brewheads. His idea of a fast cup of coffee turned out much better than he had planned, what he ended up with is a better, fuller tasting cup of strong coffee, as well as a much faster process. He found that the quicker more efficient brewing method allowed for the quality of the beans to be extracted as opposed to over extracting he had previously experienced. The term "espresso" means fast in italian, hence the term. The only problem with this machine was consistency – it was almost impossible to control pressure and temperature, since the water was heated over an open flame. Bezzera designed and built prototypes of his machine, but he didn't have any money to expand his business.
It wasn't until later when in 1903 Desidero Pavoni purchased the rights from Bezzera for the espresso machine that it became popular. Pavoni improved upon Bezzera's design and was extremely successful in marketing the product. Pavoni invented the first pressure release valve so that hot coffee wouldn't splash all over the barista when it was brewed, and also invented the steam wand to access the built-up steam that collected inside a machine's boiler to heat and froth milk for addition to the coffee. In 1905, the Pavoni company began manufacturing the espresso machines. Pavoni dominated the espresso market for more than ten years. In 1927, the first espresso machine was installed in the United States. It was a La Pavoni Espresso Machine installed at Regio's in New York.
While the early machines were successful in brewing fast coffee, the use of steam had a side effect of imbuing the coffee with a bitter taste and could only produce, at most, 2 bars of pressure. Italian engineers experimented with pumping devices to increase the brewing pressure. In 1938, Cremonesi developed the first practical piston pump which was manufactured by Achille Gaggia in 1946. In Gaggia's machine, the steam pressure in the boiler forces the water into a cylinder, which is then pressurized further by a spring-powered piston to about 8 to 9 bar. The spring that powers the piston is compressed by a lever forced down by the barista. This eliminated the need for massive boilers but kept the limit on the cylinder volume to one ounce so that the barista could provide the arm strength to “pull the shot”. This added brewing pressure created a layer of foam over the coffee – crema! Gaggia called the new drink “Caffe crema” instead of espresso, suggesting that the coffee was of such high quality that it produced its own cream.
In 1961, Ernesto Valente provided the next revolutionary step in espresso machines when he invented the Faema E61. The E61 used a motorized pump rather than a spring-powered piston to provide the 9 bar of pressure. The pump drew water directly from the tap and sent it through a spiral copper pipe inside a boiler before it was shot through ground coffee. A heat exchanger heated the tap water to the ideal brewing temperature. This provided the needed consistency for the beverage and saw the introduction of the double espresso.
The next big breakthrough came in the late 70s by a company called Ulka which developed a small, inexpensive pump that could still produce the 9 bar pressure required for modern espresso. This made small home pump espresso machines practical.
Over the last hundred hundred years or more, technology has improved the espresso machine with electrical components, computerized measurements, and smaller, efficient pumps. However, there is still an art to espresso making, despite all the technology!