How Does a Cappuccino Maker Work?

Nothing hits the spot in the morning like the deep aroma and silky feel of a big, wide cup of cappuccino. If you drink your "cuppa cappo" on the run from a paper cup, get up a bit early and make your own so you can sit for a few quiet moments before facing your day.
For those who don't quite know the difference between espresso, French roast or Turkish coffee, a few definitions may help. Cappuccino is espresso with "frothed milk." Latte is warmed milk with coffee. Espresso is the darkest roast coffee you can get which, when ground very finely and brewed using steam rather than boiling water, yields a thick, pungent liquid that is denser and less bitter than French roast or Turkish coffee, two other traditional dark roasts that can be used where "coffee" is called for in a recipe.

Freestanding espresso makers may be "pump" or "steam" machines. Most moderately-priced home market models are freestanding steam machines that work for cappuccino, too. Steam machines turn water into steam under pressure and allow it to escape through two channels, one through a filter basket containing finely-ground espresso-roast beans and a second through side vent that can be opened and closed. Steam in the coffee-brewing side condenses as it hits the metal basket surrounding the grounds and drips into the beaker or cup below, yielding a few small "shots" of finished espresso. The art of cappuccino is in the operation of the second steam outlet. A stainless steel pitcher of whole milk is slowly raised around the end of the pipe, heating the milk. When the pipe is all the way in, the pitcher is moved in a circular motion until the milk is hot to the touch and properly frothy. The milk is put in a warmed cup or bowl, reserving the froth. The espresso is added and the froth is spooned on top. This magic is achieved through a fairly simple process that super-heats water and uses a vacuum to force it through pipes toward the grounds and/or the milk. For this reason, the whole machine has to heat up before brewing can begin, hence the hisses and whistles as the process begins. Some machines work automatically, beginning the brew when the steam reaches a certain pressure and some are brewer-operated with handles to release steam. All frothing pipes have regulating devices. Because of the high temperatures and steam pressure, the entire machine, including water tanks, filters and handles, should be metal, not plastic.

Traditional Italian stovetop espresso makers, called "moka pots" were updated by the original maker for cappuccino by engineering the pot so that the milk, which is placed in an upper chamber, steams as the coffee brews in the bottom chamber. The espresso is lifted through a siphon in the center of the pot by steel into the frothing milk, making a few cups of cappuccino. The apparatus is stainless steel and sealed with gaskets to maintain the vacuum.