The Dutching process also gives the cocoa powder a darker color. Dutch-processed cocoa powder in baking is usually paired with baking powder because, as mentioned in The Difference Between Baking Soda and Baking Powder, the baking powder takes care of the acid component in leavening our baked goods.
Dutch-process powder is natural cocoa powder that has been treated with an alkalizing agent, changing the pH from a more acidic 5 pH to a neutral 7 pH. The process was invented by Coenraad Johannes van Houten, a Dutchman (thus the name “Dutch-process”).
Dutch-process cocoa powder is milder on the palate, though it can, paradoxically, have more chocolate flavor because more cacao butter is left in the powder. (Fat is a carrier of flavor, remember!)
Dutch-process cocoa is often darker in color than natural cocoa, ranging from a dark gray, to reddish brown to almost black, depending on the brand and process. The color has nothing to do with the quality or flavor of the cocoa powder.