A coffee is categorized as light or dark roasted basis the color of the roasted bean. The color of the bean indicates how long the coffee bean has been roasted in order to achieve the desired flavor profile which can range from fruity / floral (light) to oily / strong (dark).
What are coffee roast levels?
The below image illustrates how the bean color and oiliness of the bean becomes more intense as we proceed from light to dark roast.
Why is coffee roasted in the first place?
Before roasting, the green bean is akin to a cherry seed - hard and lacking flavor. Roasting is necessary as it breaks down the unripe bean releasing the 800+ aromatic compounds that give it the flavors of caramel, chocolates, flowers, and fruits which we associate with coffee. The same bean can be roasted at a different temperature and duration to extract a slightly different taste from another protocol.
What are the physical characteristics of various roast levels?
Practically, lighter roasts have no visible oil and taste slightly acidic (the mouthfeel is akin to biting an orange or lemon) resulting in a pleasant fruity sweet flavor. Lighter roasts are preferred by consumers who brew using a pour-over or advanced drip machines or aeropress (with minor effort) that are ideal for extracting such flavors.
Dark roasts on the other hand, especially from large brands like Starbucks may often be oily to the touch, if not visibly slick. These coffees have a strong bitter chocolatey flavor that many have traditionally associated with coffee. Dark coffees shine with milk-based drinks where the milk counters the bitterness and are prepared using espresso machines or moka pots.
Medium roasts sit between these extremes - offering a balance of body, strength, aroma and fruity flavor, with the darkness of the roast set in accordance with the bean.
Done well, roasting is akin to art, with skillful roasters choosing specific roast regimes to accentuate the unique flavor that can be imparted to a coffee bean by its processing, climate, altitude, soil and other interspersed crops.
Hence, for an acclaimed third wave roaster (such as Blue Tokai, Curious Life, and KC Roasters in India), you can simply choose the coffee basis the flavor notes that appeal to you.
If you are new to coffee and are shopping for coffee in a supermarket or ordering from unknown second wave roasters, please refer to our article on the rules of thumb to purchase coffee basis your preparation mechanism and roast level.