Best Coffee Maker (Automatic Drip)
Our highly recommended Best Buy coffee maker, the Bonavita 8-Cup Coffee Maker with Thermal Carafe, has been redesigned, so we tested the updated version. In addition to a $40 price hike to $189.99, the biggest change was to the coffee brew basket; formerly cone-shaped, it is now flat-bottomed. The manufacturer claims that this shape helps increase the exposure of the grounds to water, as do new, additional holes in the hot water “showerhead.” In our testing, we did see an improvement in the evenness of distribution of water throughout the grounds. An optional preinfusion setting dampens the grounds (to kick-start their readiness for the full flow of water; it’s also useful to “de-gas” freshly roasted beans). These updated features were nice additions but were not necessary to get a great pot of coffee. The carafe is now double-lined with stainless steel instead of glass, making it more durable, and it kept coffee hotter longer than the old carafe: A pot of freshly brewed coffee that started out at 190 degrees was still hot (at 163.5 degrees) 3 hours later. Overall, the machine’s design is a bit sleeker and rounder.
We measured the brew time and temperature, brewed multiple pots of coffee and cleaned up to assess its user-friendliness, and then held a blind tasting comparing identical coffee brewed in the old and new models. The Specialty Coffee Association of America certified that this new model also meets its coffee-brewing standards for optimal flavor. We found that the changes still met our standards, as well, and produced coffee our tasters enjoyed. In sum: A very good coffee maker is now even better.
However, we still have a quibble: Just like the older model, the updated model lacks a brew-through lid, so you must replace the brew basket with the lid to keep coffee hot; meanwhile, there’s nowhere on the machine to store the lid during brewing or to put the basket when the carafe lid is on. Those complaints aside, we like the improvements to this machine, and it remains our Best Buy.
How we tested
In 2008, we tested automatic drip coffee makers and got disappointing results. Only one gave us great coffee—rich and smooth. We discovered that it was the lone product to achieve research-based standards for brew cycle time and water temperature, two factors necessary for bringing out the fullest flavor in coffee without bitter notes. That machine, the Technivorm Moccamaster KBT 741, uses a powerful heating element of highly conductive copper that quickly brings water to the proper range of 195 to 205 degrees and sends it over the coffee grounds in no less than 2 minutes and no more than 8—the point beyond which undesirable flavor compounds are extracted, according to coffee experts.
Five years ago, that hand-built Dutch machine was known only to coffee aficionados, but it was easy to use and brewed a great cup. Only problem: It cost $240. Nevertheless, coffee drinkers, perhaps tired of drinking subpar brew at home or shelling out $4 per cup at coffeehouses, still snapped it up. Since then, other manufacturers took notice and launched their own high-end coffee makers. While a couple of models cost almost as much as the Technivorm, many are cheaper. All claim to reach the optimal time and temperature standards for great coffee flavor; a few have even won certification from the Specialty Coffee Association of America (SCAA), which five years ago endorsed only the Technivorm. The most important question to us: Would these newcomers produce coffee just as reliably good, and with as little fuss, as the Technivorm? To find out, we bought seven coffee makers with thermal carafes (the hot plates beneath most glass carafes scorch coffee in minutes). Among those were three models that won SCAA certification, one of which was an updated Technivorm Moccamaster, now priced at an even more staggering $299. Thirsty for a bargain, we ordered pounds of coffee and set to work.
Time and Temperature
Following manufacturers’ instructions for how much coffee to use in each model, we brewed coffee in all of the machines using the same freshly roasted batch of high-quality light-medium-roast beans. (This style of roast would make it easier to detect flaws in coffee flavor.) The brews’ surprisingly broad range of flavors and body reminded us that the machine you use can bring out the best in beans—or totally ruin them. But compared with the last time we rated coffee makers, things were looking up: Three models produced great coffee (one of them was the Technivorm). The remaining four, however, still missed the mark.
We already knew that the amount of time the grounds are exposed to water (the brew cycle) influences the quality of the extraction and which of the more than 1,000 volatile flavor and aroma compounds identified in roasted coffee beans make it into your cup. For the most desirable flavor compounds to be drawn out, that exposure can be no more than 8 minutes long, the SCAA says. If the water spends more time than that in contact with the grounds, it begins to extract undesirable compounds, leading to bitter-tasting coffee. No surprise, then, that “bitter” was exactly the word tasters used to describe the brews from the two machines that averaged more than 10 minutes to run a cycle. It also wasn’t surprising that the coffee we liked best came from the machines that stayed within the optimal range. (How coarsely or finely the coffee is ground also affects the quality of the extraction, but since there’s no way to know what grinder and what setting consumers might use, we didn’t consider this.)
Once again, we also discovered that brew temperature—that is, the temperature of the water when it’s in contact with the coffee grounds—factors into the quality of the extraction. According to the SCAA, optimal extraction happens when the water temperature spends most (ideally, about 90 percent) of the brew cycle between 195 and 205 degrees, and manufacturers are anxious to market their commitment to this standard. One even broadcast “Optimal Brew” on its label—but in that case, and a few others, the reality didn’t live up to the claims. When we ran two rounds of temperature checks on all of the machines by taping thermocouple probe wires to the center of each brew basket atop the coffee grounds (where the heated water would drip directly on them) and averaged the amount of time the water spent in the optimal zone, the so-called Optimal Brew machine barely broke 60 percent. Two others spent roughly 35 percent of the cycle in the zone; one strayed above the 205-degree ceiling for most of the cycle and made “scorched” coffee. The worst averaged a feeble 16 percent. Meanwhile, two of the three SCAA-certified models, the Technivorm and the Bunn, clocked in at 87 percent, while the third SCAA-certified model, the Bonavita, trailed slightly. The numbers lined up with our tasting results: Those that hovered in the zone the longest brewed “complex,” “velvety-smooth” coffee, while more erratic models produced “weak” coffee that “lacked depth.”
Time and temperature numbers didn’t tell the whole story, though. Our least favorite model, as well as others, brewed coffee within the ideal time range and spent more of the brew cycle in the optimal temperature zone than many machines, yet most tasters agreed that its coffee tasted weak—or, as one taster put it, like “dishwater.”
The problem came down to the simplest consideration of all: the ratio of coffee to water. “The Gold Cup ratio is 9 to 11 grams of freshly ground coffee per 6 ounces of water,” said Emma Bladyka, the SCAA’s coffee science manager and head of its certification program. (The definition of a “cup” is not standardized throughout the coffee industry; depending on the manufacturer, it can equal anywhere from 4 to 6 ounces.) That formula breaks down to between 1.5 and 1.83 grams of coffee per ounce of water. Some models suggested less and their brews tasted predictably weak, but the biggest offender was that lowest-ranked model, which recommended using just 0.75 grams per ounce—hence the “dishwater” comment.
A few manufacturers recommended using an adequate amount of coffee for a partial pot—and then warned that the ratio of coffee to water should be decreased when brewing a full pot. One 10-cup coffee maker we tested, for example, recommended one scoop of coffee for every cup but no more than eight scoops in total—leaving you two scoops short if you make a whole pot. The problem, Bladkya says, is small brew baskets. “In order to fit [9 to 11 grams of coffee per cup] in, say, a 10-cup brewer, you’d need to allow room for that coffee to expand once wetted, and a lot of brewers don’t have enough room in their brew basket.”
That’s putting it mildly. When we added the SCAA-recommended amount of coffee for a full pot to machines that called for too little coffee, the results were disastrous. One machine's basket was so heaped with grounds that we couldn’t even close its swing door. The requisite quantity of coffee caused grounds to puff up over the rim of another machine's basket during brewing, spilling down the side and onto the carafe (a problem we noticed even with a lesser amount of coffee). Coffee grounds flooded over another machine's filter, creating a lavalike mess in its basket. Any other issues these machines might have aside, we weren’t about to recommend them if they couldn’t brew a full pot with the ideal amount of ground beans.
Other design defects were merely bothersome. Adding water or coffee to some models meant moving them away from any obstructions: One coffee maker requires 2 feet of vertical space; another machine needs more than half a foot of clearance on the side—annoyances if your coffee maker must live under a countertop cabinet or wedged between other appliances. Thoughtfully designed models load coffee from the front, without requiring you to move the appliance. All the carafes kept coffee hot for at least a couple of hours, but some were hard to open and dribbled. We preferred brew-through lids; otherwise, you must remove the brew basket to pour a cup and then screw on a separate lid to keep coffee hot. One machine was just fussy to operate: While it features an attached burr grinder and is endlessly customizable, it is also endlessly time-consuming in terms of setup and features an upward-tilting display that’s hard to read. And the machine is riddled with annoying (and worrisome) reminders to clean and dry various parts or risk failure.
After brewing gallons of coffee, we had a winner. It’s utterly consistent: During every cycle, it hit the ideal temperature zone for the optimal length of time, which explains why its coffee was always smooth and full-flavored. It was also intuitive to use—a perk we don’t take for granted when we’re dialing up our first cup of coffee in the morning. On this updated model of one of our previously tested coffee makers, the manufacturer removed the manual “hold-back” switch on the brew basket that let users choose to slow or temporarily stop the flow of coffee into the carafe (which you might do to steep the grounds longer or to pour a quick cup before brewing finishes). The new model does this automatically, holding back the outflow of coffee for about 30 seconds before letting it drip into the carafe, to ensure that water fully saturates the grounds; it also cuts off flow if you pull out the carafe to pour a cup. Whether you like this change depends on how much you enjoy (and would miss) coffee-geek-like tinkering; for example, some precisionists might prefer to vary the hold-back time. (The old model is still available and we still highly recommend it.)
That said, we also identified an excellent alternative for half the money. Our Best Buy achieves nearly the same high standards for brew time and temperature as our winner, but because it heats the water to a slightly higher temperature, its coffee is brighter and slightly more acidic—a plus or not, depending on your taste preference. Either way, it’s our highly recommended Best Buy.
We tested eight automatic drip coffee makers with thermal carafes. All were purchased online.
Brew Flavor: We used the same batch of freshly roasted, freshly ground beans; brewed the beans with spring water; and followed manufacturer directions for a full pot. We held a blind taste test, assessing flavor, acidity, body, and overall appeal.
Brew Time and Temperature: We brewed full pots, measuring brew cycle time, water temperature, and the percentage of brew time that the water temperature was in the ideal range. Models that brewed coffee in no more than 8 minutes and kept water between 195 and 205 degrees for nearly 90 percent of the cycle—industry standards for optimal flavor—rated best.
Design: We assessed the coffee maker’s and the carafe’s construction and user-friendliness, including how difficult it was to fill the water reservoir and load the coffee and filter; to set up and start the machine and monitor its progress; and to open, close, and pour from the carafe, as well as to remove the used grounds and clean up.
Carafe Temperature: All carafes kept the coffee at or above 165 degrees for 1 hour and 150 degrees for 2 hours. Carafes that kept the most heat got more stars, but the score didn’t affect a machine’s ranking.
Water Capacity: We listed the water capacity of each machine in ounces because the definition of a “cup” is not standardized throughout the coffee industry. Coffee maker “cups” range from 4 to 6 ounces.