Anatomy of an espresso machine

So you understand the inner workings of an espresso machine, a very integral part of my morning routine. This post is the glossary of many of my future posts.

First, the machine is turned on which energizes a heating element in a BOILER. The boiler does one thing and one thing only, it heats water. To near boiling temperatures. Typically about 203-206F (water boils at 212F). A thermostat will ideally, maintain that temperature range of the water inside. The boiler will be refilled and pressurized by a pump. The pump is plumbed between the boiler and a source of water such as a reservoir. The pressurized boiler will send water to a GROUPHEAD. The grouphead is the interface between your boiler water and coffee grounds.

When you grind coffee. It is then DOSED, that is, dispensed into the basket. A BASKET is a stainless steel filter with a tall lip to hold grinds. The basket sits in the PORTAFILTER. The portafilter is the "thingy" with a handle that gets inserted into the espresso machine. The portafilter locks into the grouphead. Coffee grinds once dosed to the basket are then smashed together using a TAMPER. A tamper is just a heavy metal cylinder with a handle that compresses grinds together forming a PUCK, a compressed coffee grind mass resembling a hockey puck.

That puck then has hot water, from the pressurized boiler, infused through it into a small cup or glass. The small cup is called a DEMITASSE. The water dissolves soluble ions, gases, acids, and organic matter, it entrains insoluble oils and some fine coffee grinds (very few grinds). This water is now thick, rich, smooth, and slick, butter like in texture. It has a head on it like beer called 'crema', and has undertones of fruit and spice like wine, in a volumetric quantity of hard liquor. It is the pinnacle of coffee flavor, it is espresso! Or a ristretto, but we wont get into ristrettos...

-Greg