What is the difference between the first coffee roasting process and the second coffee roasting process?

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Professional coffee roasting | is coffee roasting too complicated? A picture teaches you about the baking process.

After the first article on Coffee roasting, this time we will briefly introduce the process of coffee roasting.

The process of roasting coffee

Simple analogy coffee roasting process is like popcorn, it is difficult to swallow before roasting, but like corn kernels, white fluffy, delicious and sweet popcorn pops out after roasting, and coffee roasting is the same. It also needs to go through a period of heating before it can become the coffee we drink.

The roasting process of raw coffee beans is a continuous and complex chemical reaction, generally referred to as thermal decomposition (pyrolysis), which causes coffee to produce or release more than 700 chemicals.

It is because these chemicals bring out the flavor of coffee.

Through the following video, you can see that the color of raw coffee beans changes slowly from bright green (or turquoise) to light yellow, brown and dark coffee after heating.

Start baking → for the first or second burst

In the 38-second part of the film, the water in the beans turns to steam and pops out of the coffee beans, causing the coffee beans to burst for the first time.

As the temperature continues to heat, the beans begin to swell and the silver film peels off, and the color darkens as the light coffee begins to caramel with the internal polysaccharides.

Finally, the coffee is divided from light roasting, moderate roasting to deep roasting by each baking time.

Changes of roasting degree and bitterness of coffee

Different degrees of roasting also affect the changes of chemical elements in coffee. Taguchi, a well-known coffee master, talks in his book that during roasting, chlorogenic acid (Chlorogenic Acid) [2] in coffee will produce bitter substances, and these substances will vary with different degrees of roasting. This is why the flavor of most light-roasted coffee beans is bright and refreshing while the deep-baked flavor is rich in bitterness.

On the other hand, the roaster will make the coffee show the best flavor according to the appropriate roasting degree of different raw beans.

Scientific roasting of coffee

People often compare coffee roasting to a combination of art and science, because roasters keep finding the best roasting degree and time from experiments, among which there are many factors, such as weather, water content and quality of raw coffee beans, weather during baking, characteristics of the roaster, and so on. These factors all affect the coffee flavor, so in addition to making the coffee reflect the best flavor, it is also necessary to maintain consistency!

What is interesting is that now that the scientific and digital roasting of coffee has matured, it should be hard to imagine that it was popular to stir-fry coffee at home in the United States before the mid-19th century. [3]

Reference books:

Note 1: baked taste table; Taguchi's boutique Coffee Collection; page 49; Taguchi / author; 2012; Building Block Culture publication

Note 2: antioxidants in coffee: chlorogenic acid; Zova Cafe

Note 3: coffee industry before the Civil War; long live Coffee ─ how Coffee changed the World; p. 53; Mark Pandergrast / author; 2000; Lianjing Press

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