Our science research editor said that a bar’s bitterness also corresponds to its ratio of cocoa solids to cocoa butter. Fewer cocoa solids means more cocoa butter—or fat—which produces a less-bitter chocolate. We used info from nutrition labels to calculate the amount of cocoa solids in each bar and found that our winner had the most fat and the fewest cocoa solids. So despite its 90-percent cacao content, it wasn't too bitter.
Tasters also noted a range of flavors—from stone fruit and berries to coffee and espresso. Curious to know what might cause this variation in flavors, we asked Giller, who told us, “Proper fermentation, drying, and storing procedures make a huge difference in flavor.” She added that the other major distinguishing factor in determining flavor is how long the beans are roasted and at what temperature, noting that lightly roasted beans will often have more acidity, which we can impart fruitiness, and strongly roasted beans convey toasty or fudgy flavors.
Bean origin matters, too. “Cocoa beans have terroir, just like wine grapes or coffee beans,” said Giller. Some chocolate is single origin, meaning the cacao beans used to make it come from only one location. Other products are made from blends of beans sourced from multiple places. The manufacturer of our favorite bar uses beans from Ecuador and the Dominican Republic. We asked Giller if beans from those countries had a specific profile that might contribute to our winner’s flavor and she said Ecuador's beans are often fudgy, while beans from the Dominican Republic, “often have a dried fruit sort of flavor—think prunes, dried cherries, raisins.” Indeed, several tasters picked up a rich cocoa flavor in our winning bar, as well as pronounced fruity notes that included cherries, berries, and peaches.