Coffee Composition and Type
Coffee is a solution. It contains ground coffee beans (solute) dissolved in hot water (solvent). The compounds in coffee beans, such as caffeine, chlorogenic acids, trigonelline, lipids, carbohydrates, and acids, extract into the water to form coffee’s taste and aroma. Coffee can be considered a homogeneous mixture since the dissolved substances distribute uniformly. However, coffee with undissolved components is a heterogeneous mixture. Black coffee only contains water and dissolved coffee solids so it is homogeneous. White coffee contains sugar, milk, etc. so it is heterogeneous.
Types of Coffee Beans and Preparation
The two main types of coffee beans are Arabica and Robusta. Arabica coffee grows in Africa and has a sweet, delicate flavor. Robusta coffee grows in Europe and has a smooth, non-bitter flavor. Coffee beans are roasted to bring out their flavor before being ground and brewed.
Coffee Drinks and Varieties
Espresso-based coffee drinks contain espresso, steamed milk, and foamed milk. Drinks differ in the proportions of these ingredients, changing their taste. Added flavorings also affect the taste. Coffee blends mix two or more types of beans to produce desired flavors. Beans can be blended before or after roasting. Single-origin coffee contains beans from one producer or region for a locational flavor.