An espresso machine brews coffee by forcing pressurized water near boiling point through a "puck" of ground coffee and a filter in order to produce a thick, concentrated coffee called espresso. The first machine for making espresso was built and patented in 1884 by Angelo Moriondo of Turin, Italy. An improved design was patented on April 28, 1903, by Luigi Bezzera. The founder of the La Pavoni company bought the patent and from 1905 produced espresso machines commercially on a small scale in Milan. Multiple machine designs have been created to produce espresso. Several machines share some common elements, such as a grouphead and a portafilter. An espresso machine may also have a steam wand which is used to steam and froth liquids (such as milk) for coffee drinks such as cappuccino and caffe 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. This design is still used today in lower-cost consumer machines, as it does not need to contain moving parts. Also, steam-driven machines do not produce as high of a pressure for extraction compared to pump-driven. This results in the crema, a hallmark of an espresso, being of lower quality.
One of the many issues with other coffee makers is that the brewing process is inconsistent, with temperature fluctuations that can potentially affect the acidity, aroma, and final flavor of your beverage. The OXO On Barista Brain Coffee Maker is fixed with an intelligent microprocessor that monitors ambient temperatures throughout the brewing process.
Tamp: To ensure the espresso is evenly packed, your machine comes with a tamp, which you’ll press into the basket against the grounds. This step is important: When you pull a shot, the water will go to the place of least resistance, avoiding densely packed areas. This denser espresso won’t be properly saturated, making it under-extracted and sour, while the looser espresso will be over-extracted and bitter.