Michaele Weissman's 10 Ways to Judge a Cup of Coffee:
1. The Scent
Our sense of smell is much more sensitive than our sense of taste. Anyone who has been captivated by the smell of coffee won't be surprised to learn that coffee releases more aromatic compounds than any other food. These should be pleasing aromas, but bad coffee may include onion-y and vegetable-y elements in its scent.
2. The First Sip
Try tasting each new coffee black. Nothing is wrong with milk and sugar, but they alter the taste and texture of the coffee. So, when learning about coffee, it's a good idea to take a few pure sips. Also, let it cool slightly to make the range of flavors in the cup more accessible.
3. Sweetness and Saltiness
Look for an underlying natural sweetness. That taste comes from the ripeness of the coffee cherry. Professional tasters rank sweetness as the most important taste characteristic of high-grade coffee. Coffee should never taste salty. Saltiness is caused by processing defects.
Taste for a bright, light acidity that is pleasing. This is not to be confused with the stomach-churning acidity that you get, say, from coffee that has been sitting on an office hotplate for four hours.
A nice texture for coffee has a little thickness. It's not thin and watery. The last taste you experience with good coffee should be smooth, and there should be a pleasing, sweet aftertaste.
6. Fruits and Vegetables
Finding words to describe the interplay of what our taste buds detect (sweet, sour, salty, bitter, and savory) isn't easy. Many of the world's most prized coffees, such as those from Yirgacheffe in Ethiopia, abound in flavors that are described as bright, lemony, orangey, berry-like, and floral. When the fruity flavors go bad, however, they can degenerate into vegetable tastes. Not so good. Who wants sautéed onions or steamed cauliflower in their coffee cup?
Exotic flavors that are spicy (think cinnamon and cloves), smoky, and woodsy can be desirable. Such tastes often appear in Indonesian coffees. In excess, they can be unpleasant.
8. Natural Sugar
Chocolaty, caramel-like, nutty, and toasty flavors come from the sugar browning that occurs during roasting. Latin American coffees at their best have lots of these yummy, warm, sweet notes. In lower quality coffees from Latin America (like some of the national brands you buy at the supermarket), this sugar browning can produce the sense of swallowing a mouthful of dry, bitter grain.
9. The Roast
Roasting can be light, medium, dark, or very dark. If you detect a burnt quality in a coffee, it may be a bad roast. In the U.S. there are regional differences in roasting. Companies from the Pacific Northwest tend toward darker roasts.
10. Espresso Notes
Espresso is made from a blend of coffees brewed under great pressure, using a large amount of coffee and a small amount of water. Espresso is dense and intense and can stand up to other flavorings. High quality espresso has just as complex a flavor range as brewed coffee. If you order an espresso in a café, the layer of reddish brown foam on the top, called the crema, should be thick and creamy, and you should be able to push it away from you with the back of a spoon. If you order a cappuccino, the milk foam should be thick, creamy, and sweet.
Tip: Knowing where your coffee comes from can help you pick one that will taste great to you. Latin American coffees tend to be chocolaty and mild. Coffees from east Africa tend to have a wake-up-your-mouth kind of perkiness that coffee pros call brightness. Coffees from Indonesia tend to be earthy, dark, and more intense. Would you like to know more?