The Key Words of Espresso
Like any other field, espresso has its own little language that you should know. Below is a small list of key words that you'll often hear when reading about anything espresso.
BAR: Pressure rating used on most pump driven espresso machines. 9 BAR, the typical accepted pressure for brewing espresso is 8.8 atmospheres of pressure or 130 pounds per square inch. Almost every consumer espresso machine is capable of producing this pressure consistently.
Burr Grinder: is the recommended type of grinder for proper espresso making. A burr grinder features two disks, one stationary, one rotating, which slice away portions of a coffee bean into very fine particles.
Crema: is one of the sure signs of a properly brewed shot of espresso (in non crema-enhancing machines) and is created by the dispersion of gases - air and carbon dioxide - in liquid at a high pressure. The liquid contains oils and forms a dark golden brown layer resembling foam on top of an espresso shot.
Demitasse: the cup that holds a traditional shot of espresso is called a demitasse - the fancy word for the small 3 ounce (or smaller) cup. Demitasses can be made of ceramic, stainless steel, or glass, though porcelain is often the preferred material. The thicker the better, as they must retain heat well in that small 1.5 ounce beverage you craft.
Dosage: refers to the amount of ground coffee used to produce a shot of espresso. Usually 7 grams per 1.5 ounce single espresso shots.
Doser: found on many burr grinders, especially those designed to be used with espresso machines. A doser releases a measure of coffee grounds as you pull on a lever that is built into the side of the doser.
Filter Basket: is a metal, flat bottomed "bowl" shaped insert that fits inside a portafilter. The filter basket holds your bed of ground coffee and has a multitude of tiny holes in the bottom to allow the extracted beverage to seep through and pour into a demitasse cup or other receptacle. Most espresso machines include two filter baskets, a single basket and a double basket, though some machines feature convertible baskets that allow either a single or double shot of espresso to be produced from the same basket.
Frothing Tip: refers to the perforated tip on a steaming wand. These can have between one and four holes, and the holes can be either angled to the side or pointing straight down. They allow the steam from the espresso machine to be forced into tiny jets which agitate and heat milk at a great pace and also facilitate proper frothing when used to introduce air into the milk.
Portafilter: (also known as a groupo) the device that holds a filter and finely ground coffee and facilitates quick attachment to an espresso machine. Portafilters almost always feature a handle for easy handling, and spouts underneath to allow your espresso to pour into cups. On better espresso machines, they are made of copper or brass, and are coated with chrome. The handles are usually wood, bakelite, or plastic. On less expensive machines they can be aluminum, steel, or other metals and plastics.
Pull: a term used to describe brewing a shot of espresso. Comes from the action used to prepare espresso in the 1950s, 1960s, and beyond - pulling on a lever to cock a spring in a piston group on an espresso machine. Also Espresso Pull, Pull a Shot.
Steam Wand: is a visible, external pipe found on most espresso machines that is used to froth and steam milk, to provide hot water (on some machines), and heat espresso cups. Some also use the steam wand to heat water. It is controlled by a steam knob that opens and closes the steam valve inside the machine.
Shot: another term to describe a brewed espresso.
Tamp: (also tamping) the act of pressing and compacting a bed of loose, finely ground coffee, in preparation for brewing espresso. Different machines require different tamping methods. Steam powered espresso requires a leveling tamp, where piston lever, spring lever, and pump espresso requires a more compacting action. Some prefer a heavy tamping action (using 25 or more pounds of pressure), others prefer a light tamping action (less than 15 pounds of pressure exerted).
Tamper: the device used to tamp a bed of loose, finely ground coffee in a portafilter, in preparation for brewing espresso. Most espresso machines include a plastic tamper as an accessory, and after market tampers can be bought. They are measured in millimeter sizes, corresponding with the filter basket internal diameter of your espresso machine. Most commercial, prosumer, and high end consumer espresso machines use a 58mm tamper; other common sizes are 49mm, 53mm, and 57mm.
Thermoblock: in some espresso machines, the heating system is shaped similar to that of a car radiator, a series of heated metal coils or channels which water must pass through and become progressively hotter as it reaches the boiler.