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.
The simplicity starts with its design: a single button with a scrolling dial underneath an LED interface. That button is the only one on the entire machine. With it, you set the time, set the water temperature, set how many cups you want brewed, and when you want the brewing to start. It takes a second to get the hang of it, but we were impressed with how intuitive it is — a stark contrast to a machine like the Moccamaster KBT 10-Cup Coffee Brewer, which had so many extra pieces, it required constant consultation of the instruction manual.
CR’s take: Though this Bialetti lacks typical drip-machine features such as programming and brew-strength control, it more than compensates with a Very Good rating in our brew performance test and a crisp 8-minute brew time. If you’re the type who sometimes prefers a morning shot of espresso to a cup of joe, this twofer—drip machine beside espresso maker—may be for you. It features a built-in milk frother, a permanent coffee filter, and auto-shutoff. CR does not yet have enough survey data on Bialetti machines to rate them on reliability and satisfaction, but when we do, we’ll add that info to our ratings.
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.
Our brew-performance tests measure the brew temperature and contact time (how long water stays within a sweet spot of 195° to 205° F for brewing). We measure concentration using a refractometer, a device that measures the amount of coffee dissolved in each brew. Our convenience tests look at how easy it is to set timers, fill the reservoir, clean the machine, and more. And for the first time, we’re incorporating predicted reliability and owner satisfaction ratings into the new Overall Score for each model. We determine these ratings for each drip coffee maker brand using survey data collected from thousands of CR members.