ACCORDING TO MY extremely unscientific, improvised testing methods, it seems that coffee lives in the Goldilocks Zone—not too hot, not too cold—for only about 8 minutes. Typically, after pouring a cup, I sip it tentatively, anxiously, until it reaches my preferred temperature, then gulp the rest down the way I chug Gatorade after a 5K run so I don’t waste its peak.
Apparently there’s a better way. The Ember ceramic smart mug ($80, ember.com) comes equipped with a built-in microprocessor and a dual-zone heating element at its base that lets you control it via smartphone. This discreet bit of tech lets you handily dial up or down the coffee’s temperature and keep it stable for about an hour (until the battery fades), which is right on target according to experts.
“Coffee degrades after an hour. Period,” said Paul Schlader, co-founder of New York City’s Birch Coffee chain. “You can’t stop that. But a heater can help prolong a bit of that sweet spot.”
The coffee’s temperature is measured using three internal sensors and is displayed in real time on the mug’s companion app, where you can customize preset temperatures or use theirs—126 for a latte, 130 for coffee, 132 for tea.
“Most coffees from different regions are going to be represented well in that space,” explained Mr. Schlader. “But the optimal temperature for flavor, aftertaste, the correct amount of acidity and body is about 135 degrees.”
For coffee drinkers who don’t enjoy feeling the burn, Ember’s pricier travel mug option ($150) has a “rapid cooling system” that pulls heat out of the cup to cool it more quickly so you’re not left waiting.
I recklessly pushed the Ember and my caffeine intake to the limits one Sunday, testing cups at varying degrees from the mug’s max of 145 F—not recommended—to its low of 120 F, where you begin to see how the quality of a brew stands up, according to Mr. Schlader.
Each time the Ember performed. However, getting bombarded with persistent smartphone notifications about updated temps and the need to charge my mug got old very quickly. I don’t need yet another device distracting me from my work—not when I have all this important science to do.