Filtered coffee is any coffee which is brewed through some type of filter so the grounds don't end up in the drink. Those who enjoy a cup of grounds-free coffee can choose anything from drip brews, shots of espresso, Indian filter coffee and more. Filtered coffee wasn't before the early 1800s, centuries after the drink became a popular staple in Arabia, circa 1000 AD. Up until that time, coffee had been made with the grounds still in the water. Although the basic principles behind filtering coffee haven't changed much, there are many different appliances and methods for filtering, each resulting in variations on flavor and richness.
The filtered coffee movement began around 1780 with the invention of Mr. Biggin coffeepots. The Mr. Biggin pots were shaped something like a tall teapot, containing room for a fabric filter and a spout at the bottom. By the early 1800s, coffee inventors had much improved on the flaws of the Mr. Biggin, offering disposable cloth filters to prevent the rotting that happened with repeated use of a single filter. Over time, cloth filters were replaced entirely with paper filters.
Even with improvements, these filtered makers weren't perfect at keeping grounds out of the coffee, hence the invention of the vacuum brewer. Vacuum brewers have two large water holding containers, like two pots stacked on top of each other. Water is placed in the bottom chamber where it is heated to boiling. The heat pressure forces the water into the upper chamber, which contains coffee grounds. Once the heat subsides, the water naturally filters back down into the lower chamber, resulting in a rich and grounds-free pot of coffee.
Coffee percolators took the technology behind the vacuum brewers and placed it in a far-less bulky device. A percolator is a vertical pot with a spout at the top. Water is placed in the bottom of the pot. When the percolator is heated, either by stove top or electrical outlet, the water is forced up into a brew chamber containing coffee grounds. The resulting coffee flows back down into the bottom, while the grounds remain at the top. Many percolators have a viewing window so the user can judge the strength and consistency of the coffee.
The French press soon followed, which features one cylindrical container with a plunger inside. Coffee and water are combined in the container and heated. When the plunger is pressed down, the water is able to escape up the side of the container, while the grounds remain trapped at the bottom. This method is one of the simpler but effective ways of making filtered coffee. Whereas the bulky vacuum brewers have been relegated to collectors' items, the French press is still used by some who prefer it for the easy control it offers to the user.
Today, one of the most popular methods of making filtered coffee is with an automatic drip coffeemaker. Electricity heats water, which is then poured through coffee grounds placed in a filter; the water absorbs coffee as it seeps through into a pot. If the filter is set up correctly and holds the grounds properly, there should not be any grounds that make their way into the pot. Automatic drip coffeemakers have become so popular since their introduction in the 1970s that they've become a common kitchen appliance.
Over time, filtered espresso coffee has become nearly as popular and accessible as drip coffee. Espresso is made with finer coffee grounds than drip. The grounds are tightly packed into a small chamber, through which hot pressurized water is forced. Espresso is often much darker and bolder than most drip coffees. As a result, it is not brewed in the same quantities as drip, but in shots. Espresso shots can be consumed in many forms. Some drink it straight up, some with a blend of steamed milk, and others with water.
In India, many enjoy drinking Indian filter coffee, which uses a blend of chicory and dark coffee beans. This style of coffee is filtered using a set of tumblers. The coffee and chicory is tightly packed into one of the tumblers, while the other tumbler is placed on top prior to adding hot water. The water blends with the coffee and chicory, and slowly froths and drips to separate the drink from the grounds. The chicory helps the coffee retain its boldness and strength. As a result, Indian filter coffee is generally stronger than many Western methods of filtering coffee. This style of coffee is often had with milk.