†Programmable Brew Time: Conventional wisdom frowns at grinding beans early and programming a pot to brew later. The aromatic compounds in coffee beans start to oxidize as quickly as 15 minutes after grinding, which causes coffee to start losing aroma and flavor. But Michael Ebert, senior consultant at Firedancer Coffee Consultants, LLC, assured us that, given the trade-offs for convenience, “grinding the night before will still make a great coffee — just not as great as it could be.” Seven of the 10 pots we tested are programmable, including three of our top picks (all but the Bonavita).
A portafilter (or group handle) attaches to the grouphead of semi-automatic and piston-driven espresso machines, and carries a tamped puck of coffee grounds within its basket. It is usually made of brass for better heat retention, and is attached by a plastic or wooden handle. The portafilter forms a seal with the espresso machine's gasket, and directs high-pressure hot water through the coffee puck. After-market retailers also sell bottomless portafilters that minimize the espresso's contact with any metal. A bottomless portafilter is one tool baristas use to analyze the quality of the coffee grind and the evenness of the extraction and allows for a visual check of "channeling" or the condition in which water is able to pierce a hole in the espresso puck during the brew process leading to poor extraction. Often, baristas use knockboxes to store their spent espresso grounds after they have pulled a shot.
The principle of a vacuum brewer was to heat water in a lower vessel until expansion forced the contents through a narrow tube into an upper vessel containing ground coffee. When the lower vessel was empty and sufficient brewing time had elapsed, the heat was removed and the resulting vacuum would draw the brewed coffee back through a strainer into the lower chamber, from which it could be decanted. The Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925.
Let’s circle back to that extra-long brew time. There are two factors that didn’t make it an automatic “no” for us. The first is that the OXO On 12-Cup is programmable. Like our experts say, grinding coffee in advance isn’t going to make the most perfect cup of coffee. But the fact that you can program the machine’s “wake-up time” to start brewing and have coffee ready when you are takes the sting out of the wait.