There were lots of innovations from France in the late 18th century. With help from Jean-Baptiste de Belloy, the Archbishop of Paris, the idea that coffee should not be boiled gained acceptance. The first modern method for making coffee using a coffee filter—drip brewing—is more than 125 years old, and its design had changed little. The biggin, originating in France ca. 1780, was a two-level pot holding coffee in a cloth sock in an upper compartment into which water was poured, to drain through holes in the bottom of the compartment into the coffee pot below. Coffee was then dispensed from a spout on the side of the pot. The quality of the brewed coffee depended on the size of the grounds - too coarse and the coffee was weak; too fine and the water would not drip the filter. A major problem with this approach was that the taste of the cloth filter - whether cotton, burlap or an old sock - transferred to the taste of the coffee. Around the same time, a French inventor developed the "pumping percolator", in which boiling water in a bottom chamber forces itself up a tube and then trickles (percolates) through the ground coffee back into the bottom chamber. Among other French innovations, Count Rumford, an eccentric American scientist residing in Paris, developed a French Drip Pot with an insulating water jacket to keep the coffee hot. Also, the first metal filter was developed and patented by French inventor.
This testing was designed to highlight the difference in how each machine extracted its coffee grounds. Remember, extraction is tied to water temperature, how long the grounds had to steep, and how evenly that water is distributed in the brew basket. (Depending on how the machine distributes the water and the shape of the basket, any particular ground may or may not receive the same amount of time in contact with water — thus any individual grind may be over-extracted, under-extracted, or just right.) Properly extracted grounds would have a balance of notes and aromas, from slight hints of acid to a pleasant amount of bitterness.
If you’re shopping for coffee at the grocery store, “check the roast date, rather than the ‘best by’ date,” says Awan. With mass market roasters, the “best by” date can obfuscate the window in which coffee beans are at their best: about 4 days after roasting, when some, but not all, of the carbon dioxide has escaped from the beans. (Too much carbon dioxide captured within beans tends to create uneven extraction, as the gas escapes — this is what pre-infusing tries to counter. Conversely, too little carbon dioxide in the bean can lead to a loss of flavor.)
It can take a little while to get to know the ins and outs of a new coffee maker. In CR’s labs, each drip coffee maker we test brews roughly 65 cups by the time our engineers are through with it. And brewing is just one of many aspects we look at. We test for handling and convenience, too, so you can choose a model that helps you sail through morning madness.