Both your coffee beans and your brewing method make a difference in the acidity of your morning cup of joe. To reduce the acid in your coffee, and decrease the likelihood of stomach upset, start with beans naturally low in acid, learn how roasting affects acidity, and use processed low-acid coffee.
Beginning With the Beans
Select coffee that's processed to remove acidity or that's naturally low in acid because of the region in which it's grown. Low-acid coffees marketed as stomach-friendly or "mild" coffee have been processed with steam or solvents to reduce acid. Coffee from Brazil, Sumatra and Hawaii tend to be naturally lower in acid than most coffees, and many coffees from the Caribbean and India are also low in acid. Descriptions from coffee suppliers and catalogs usually identify coffees by region and describe acidity.
The Dark Roast Effect
Dark roast coffee, which includes French roast and Italian, is less acidic than medium and light roast coffee. If you buy coffee in bulk, look for dark beans. The longer the coffee is roasted, the darker it becomes while it undergoes chemical changes, resulting in lower acidity. Dark roast coffee stimulates less stomach acid secretion than a lighter roast. Dark roast coffee has less caffeine than lighter roasts, too, another factor that can make these brews less acidic where it counts. Make dark roast coffee by any method you prefer. If you're unfamiliar with the taste of dark roast coffee, try using a smaller amount per cup to start.
Cold brewing results in lower acid using any kind of bean and roast. This infusion method doesn't require heat, although it does take longer to brew. Overcome the brewing time inconvenience by setting up the coffee to infuse overnight. Coffee-supply retailers sell cold-brewing systems, or to try this method at home with little to no expense, use a jar or pitcher with a lid. Stir 1 pound of ground coffee into 9 cups of cold water in the container; cover it and leave the coffee to steep for 10 to 12 hours. Filter the coffee with a screen or a paper coffee filter; the resulting coffee concentrate keeps for up to two weeks without losing flavor. Add hot water to taste for hot java or chilled water for an iced coffee.
Scandinavian and Boiled Coffee
A long-standing tradition for making Swedish and Norwegian coffee calls for brewing it with eggshells, which contain calcium that neutralizes acid. Crush the eggshells and add them to the coffee grounds before brewing to reduce acidity and bitterness. In some recipes for Scandinavian-style coffee, sometimes called "church basement coffee," whole eggs are mixed into the grounds to clarify the brew without adding flavor. Cowboy coffee, also called boiled coffee, makes use of eggshells, too. Use 1 eggshell per each 2 cups of water and 1 tablespoon or more of ground coffee to taste. Boil the grounds and eggshells together in a stainless steel or enamel pot and strain the brew. This style of coffee is convenient for campfire cooking because you can make it in a saucepan.