While you can use any type of coffee you’d like in cold brew coffee — because the cold brewing process uses cold water rather than hot water, it isn’t really able to extract many of the acids you find in hot coffee — we recommend coffee beans for which acidity isn’t a major selling point. You’ll likely be better off cold brewing coffees with lots of body and sweetness. That certainly describes darker roasts, but don’t shy away from lighter roasted natural coffees, which often carry tons of fruit flavors that are much sweeter than they are acidic. If you want to let us do the work of choosing coffees for you, we’d love to help you build a personalized coffee subscription and help you find your perfect coffee match.
Because cold brew is an immersion brew method (meaning the coffee is completely submerged in water and stays in contact until the brewing is done), you want a very chunky, coarse grind size. The larger the surface area, the longer it takes for the water to extract the delicious stuff out of the coffee beans.
If you’re using a burr grinder, which has a vastly more even grind size for better flavor extraction, you’ll want to use the higher number settings. If you use a blade grinder, just don’t grind for nearly as long as you would for, say, a drip machine. If you’re buying your coffee beans pre-ground, you should be able to ask for it to be ground for cold brew, but if all else fails remember the word “coarse”.