The magic behind coffee roasting, a journey into the chemical changes of green beans

Coffee roasting is a magical process that puts the raw beans through a unique journey of chemical changes. During the roasting process, the color, aroma and taste of the coffee beans will change significantly, and their internal chemical composition will also undergo chemical reactions to produce hundreds of different aromas and flavors. The roaster needs to master the temperature and time to awaken the potential of the coffee beans, release the unique aroma, and lay a solid foundation for subsequent coffee making.

In the world of coffee, roasting is a mysterious and fascinating process. When green beans begin to undergo roasting, what kind of transformation do they go through? Many people may think that roasting is just roasting the coffee beans to the right state, but in fact, it contains a wealth of chemical changes that affect the final taste and aroma of the coffee.

1. Green beans before roasting

The green color of raw coffee beans is due to the chlorophyll they contain. At this point, the chemical composition inside the coffee beans has not yet been decomposed and reorganized, and the taste is extremely bitter, which is very different from the coffee we drink every day.

2. Start the baking process

As the temperature rises, the roasting process begins, the moisture inside the coffee beans begins to evaporate, and you can hear the beans crackling in the roaster, which is a sign that roasting has begun. The volume of the coffee beans will expand slightly and the color will begin to change.

3. The beginning of chemical change

As the temperature continues to rise, the starch in the coffee beans begins to convert into sugars, and some carbohydrates will also decompose. At this time, the color of the coffee beans will significantly deepen, and the enzymes inside the coffee beans will become active, catalyzing a series of complex chemical reactions.

4. Release of coffee beans’ aroma

When the temperature reaches about 180 degrees Celsius, the oil in the coffee beans begins to seep out, which makes the surface of the coffee beans appear glossy and the unique coffee aroma begins to emanate. This is the most fascinating moment in the roasting process. Different degrees of roasting will produce different aromas, from lightly roasted nutty aroma to darkly roasted caramel aroma, all of which are formed in this step.

5. Reshaping flavor and taste

As the roasting progresses, the taste and flavor of the coffee beans also change. Some acids begin to decompose or transform, reducing the overall acidity of the coffee; new flavor components also begin to form, giving the coffee a unique charm. This is why the same coffee beans have completely different tastes and flavors at different roasting degrees.

In this process, we need to pay attention to the fact that every detail in the roasting process may have a significant impact on the final quality of the coffee. From temperature control to time control, we need to treat them carefully. Any slight mistake may affect the taste, aroma and even healthiness of the coffee.

6. More than just physical changes

In this process, you might think that only physical changes lead to the transformation of coffee beans, but in fact, the real magic happens at the chemical level. Countless chemical reactions take place simultaneously in tiny coffee beans, which change the properties of coffee beans and also bring us a colorful coffee experience.

The coffee roasting process is not only a process of transforming raw beans into cooked beans, but also a wonderful chemical journey. In this process, the raw coffee beans undergo a leap from quantitative change to qualitative change, bringing us a unique taste enjoyment. Next time you are tasting a cup of fragrant coffee, you might as well think about the magic hidden behind it.