How Coffee Percolators Work
The modern design of a coffee percolator was patented in 1889, and it quickly became a popular household item until it was replaced by the automatic drip coffeemaker used in most homes today. A coffee percolator heats water to a boil, and the water moves up a metal straw and falls through a metal basket containing ground coffee beans. The coffee falls to the bottom of the pot and moves up the straw again, circulating through the machine. Many percolators have a glass or plastic cap on the lid to show the color of the coffee as it circulates.
Percolators can be used to make stronger coffee than drip machines because the coffee can percolate until the desired strength is reached. Some consumers think that boiling the water can cause the coffee to taste burnt or bitter; other consumers prefer the strength of coffee made in a percolator to coffee made with an automatic drip machine. Even though it is stronger than drip coffee, percolated coffee is still lighter than espresso.
How Espresso Machines Work
The espresso machine was invented in Italy in 1901. The word "espresso" means "made in the moment" in Italian, emphasizing the quick preparation of this coffee drink. Finely ground coffee, usually made with dark-roasted beans, is pressed into a metal filter. The filter is then attached to a machine that forces steam through the coffee grounds, producing a thick, dark coffee drink in under a minute. Many espresso machines also use steam to heat milk and produce milk foam that is then added to the espresso.
Espresso usually has a very rich, dark flavor because coffee beans used for espresso are usually roasted longer than drip coffee beans, and steam preparation produces a concentrated coffee drink. The prepared drink is dark brown with a light caramel foam.