This blog post explores the importance of the roasting process in shaping coffee’s taste and aroma, the changes that occur at each stage, and the differences in flavor profile based on roasting methods.
In modern society, it’s common to see many people enjoying coffee. Coffee has become an everyday beverage due to the Westernization of diets and increased preference for it. However, while many people love coffee, they often don’t fully understand its diverse flavors. If you take an interest in what flavors and aromas emerge during the coffee-making process, you can enjoy coffee more deliciously, tailored to your personal preferences. This article will focus on roasting among the various factors influencing coffee’s flavor profile. First, we’ll explore the necessity of roasting, then explain the types of machines used for roasting, and finally describe the roasting process and its stages.
The coffee roasting process is often described using words like magic, art, or science. The reason is that green coffee beans themselves have no inherent taste or aroma. The distinctive flavors and aromas we experience when drinking coffee are not characteristics of the green beans themselves. Only through the roasting process, which transforms green beans into roasted beans, do the coffee’s taste and aroma come into being. Therefore, understanding the roasting process is crucial for creating the desired coffee.
Machines used for roasting are broadly categorized into three types. First, the direct-fire method involves the coffee beans being roasted directly over an open flame. While it has the advantage of completing roasting quickly, it requires careful attention as the beans can easily burn. Second, the semi-hot-air method heats the drum containing the beans with a heat source, roasting them through heat conduction. Compared to direct-fire, heat is distributed more evenly, making it easier to monitor the roasting progress. Finally, the hot-air method roasts the beans suspended in high-temperature hot air, offering the most uniform roasting results among the three methods.
While choosing the roasting machine is important, understanding the roasting process itself is paramount. The roasting process can be broadly divided into: loading, Yellow stage, First Crack, Second Crack, and cooling. When the beans are loaded, they are heated to temperatures between 260°C and 500°C. When the internal temperature of the beans reaches 100°C to 130°C, moisture evaporates and the beans turn yellow, entering the Yellow stage. At 140°C, the beans’ carbohydrates, proteins, fats, and organic acids decompose, releasing carbon dioxide. At 150°C, the beans expand through an endothermic process, known as the First Crack stage. The second crack occurs at 200°C when the beans undergo pyrolysis, triggering an exothermic reaction. Once the internal bean temperature reaches 220°C to 230°C, roasting must be stopped, and rapid cooling initiated to prevent charring. Cooling is achieved by circulating cold air or spraying water.
The roasting process can be divided into detailed stages based on intensity. While this varies slightly by country or region, it is generally classified into eight stages: Light, Cinnamon, Medium, High, City, Full City, French, and Italian. The Light and Cinnamon stages correspond to light roasting, Medium and City to medium roasting, and Full City to Italian to dark roasting. A higher intensity means a longer roasting time.
Generally, short roasts emphasize acidity, while longer roasts emphasize bitterness. In the light and cinnamon stages, which are light roasts, acidity is pronounced and the coffee’s characteristic aroma is almost absent. Medium roasts develop a mild acidity alongside a distinctive aroma. The high roast stage occurs just before the second crack begins, after the first crack ends. From this point, bitterness starts to intensify, harmonizing with the acidity. In the city roast stage, sweetness peaks, and bitterness becomes stronger than acidity. In the full city stage, acidity almost disappears, bitterness dominates, and the coffee’s inherent aroma becomes very strong. During French and Italian roasting stages, a charred taste emerges due to the carbonization of starches and sugars. Thus, the degree of roasting can be judged not only by changes in taste and aroma but also by the color of the coffee beans. The green green beans gradually turn yellow, then light brown, and finally deep brown, becoming black in the final Italian roasting stage.
We have now explored coffee roasting. Green coffee beans possess no inherent flavor or aroma; it is only through the roasting process that coffee’s unique flavor profile is created. Roasting is an essential step in producing a single cup of coffee. Coffee contains a surprisingly diverse range of flavors and aromas, and roasting is one of the key factors determining this flavor profile. Beyond roasting, factors like bean variety, grind size, brewing equipment, and blending processes also influence coffee’s flavor profile. By harmonizing these various elements, we can create a delicious cup of coffee. Next time you enjoy a cup, consider these factors and focus on its taste and aroma; doing so will allow you to savor coffee in a richer, more fulfilling way.
