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.”
