Most models turn costly beans into mediocre coffee: too weak, too flat, or too bitter. What’s so hard about making a decent drip coffee maker?
In this age of Starbucks, Americans have gotten much more sophisticated about the complexities of coffee flavor. As we surveyed the latest models on store shelves, we wondered if manufacturers might have caught up with our coffee obsession and finally developed an automatic drip coffee maker that can produce a terrific brew.
From previous tests, we knew that a thermal carafe would be essential; the usual hot plate under a glass carafe starts turning fresh coffee acrid in a matter of minutes. We found eight brands with thermal carafes and at least a 10-cup capacity at prices from $47 to nearly $300. Most were programmable, meaning you can fill them with coffee and water and set the time you want the pot to turn itself on. Two came with an attached burr-style coffee grinder.
Better Brew
Brewing a full pot in each machine, we asked tasters to judge the coffees’ aroma, body, complexity of flavor, level of bitterness, and overall appeal. Our hopes for the new generation of coffee makers were quickly crushed. Most of those eight stainless steel machines made the same kind of mediocre coffee we’ve come to expect: bitter, weak, or one-dimensional.
What was the problem? Aside from using fresh, high-quality coffee beans and good-tasting cold water, the two most important factors in making good coffee are the water temperature as it passes through the grounds and the length of time the grounds are exposed to the water. These factors determine which of the more than 1,000 volatile flavor and aroma compounds identified in roasted coffee beans make it into your cup and which get left behind (only a limited number of them—approximately 30—produce the best-tasting coffee). Studies have shown that the most flavorful, aromatic compounds are released by water between 195 and 205 degrees Fahrenheit, at a brew time of six minutes, for drip coffee makers. The ideal cup of coffee contains 18 to 22 percent suspended solids extracted from the ground coffee. Too fast a brew time and the extraction of solids will be less than 18 percent, and your coffee will be weak; too slow a brew time leads to overextraction (more than 22 percent suspended solids) and a bitter brew. If the coffee maker is too slow and the water is not sufficiently hot, you can even wind up with coffee that is both weak and bitter.
We made more coffee, this time measuring the water temperature throughout the brew cycle. And here we made a key discovery: Most of these machines were too cool, spending most of the brewing cycle struggling to bring the water into the right temperature range. Many didn’t reach the correct temperature until the last minute or two of brewing—and then kept climbing, scorching the grounds as the last few cups dripped into the carafe.
Next, we timed three pots in each coffee maker with a stopwatch and averaged the results. Once again, our lousy coffee could be explained: Most of the machines never reached that ideal time frame for water to pass through the coffee grounds, though two came much closer than the rest. The slowest machine took 18 minutes to make one pot of very bitter coffee. The fastest took just four minutes, and tasters found its coffee weak, thin, and flat.
Tasters’ Choice
How can manufacturers keep getting away with these crimes against good coffee? They know consumers can’t taste the coffee before they buy the machine; most choose a coffee maker based on looks and price. New models are dressed up to be enticing, with graceful carafes, backlit digital displays, and multiple features. Why can’t the flavor match up? To sell these coffee makers competitively, the machines have to be made cheaply, and the most expensive part of the coffee maker is the heating element.”
In the end, only one coffee maker stood out in our tests as exceptional. Unlike any of the other coffee makers, its internal heating element brought the brewing water to the correct temperature range within seconds and kept it there through the brewing cycle. In contrast to most coffee maker heating elements, which are made of aluminum, our winner’s heating element is made of far more expensive copper. In coffee makers, the heating element usually runs alongside a tube containing water. As the cool water drips down from the tank, it passes through the heated channel, then boils up to the top of the machine, and finally drips down onto the grounds. A copper heating element has higher thermal conductivity than aluminum, meaning it is more responsive and can reach a higher temperature more quickly.
There was just one problem with our winner—its price. Could we really justify spending almost $250 when we know that great coffee can be had through far cheaper methods? To make sure, we compared the machine made coffee to coffee from a French press, the method favored by many coffee connoisseurs. To our surprise, while our tasters enjoyed the French press coffee’s rich aroma and flavor, the machine still won the day with even better flavor—and with no need to go through the French press’s multiple steps of separately heating the water to 200 degrees, then pouring, stirring, waiting four minutes (according to manufacturer instructions), and pressing.
See the Results
