Ask Marilyn

Is the strength of coffee determined by the type of bean? Or by the roast?

—S. Keene, Easthampton, Mass. Ah, so many varieties of coffee beans and roasting techniques, so little time to enjoy them all! (Yes, I’m a fan of coffee.) Misinformation on this subject is vast, and few correct generalizations exist, but here’s a pertinent one: Although beans do differ greatly in caffeine content and much more, roasting increases the size and reduces the density of any coffee bean, so scoop for scoop (volume), light roasts produce coffee with more caffeine, but ounce for ounce (weight), dark roasts produce more caffeinated brews. Darker roast coffees taste stronger because they have more dissolved solids.