Coffee roasting knowledge sharing, roasting will produce volatile and non-volatile compounds

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Volatile and non-volatile compounds are produced during baking. Generally speaking, volatile compounds are aroma, and non-volatile compounds are flavor.

Volatile compounds are organic chemicals with high vapor pressure at room temperature, many of which are formed in the degradation reaction or in the development stage of baking. When the volatile compounds escape, we will smell the unique aroma of this coffee, including:

Aldehydes: bring fruit aroma, green aroma.

Furan: helps caramel smell

Pyrazine: has the smell of dirt.

Sulfur compounds: including 2-furfuryl mercaptan. Some of these compounds are often described as having the aroma of "roasted coffee", but some substances are unpleasant when smelled independently. For example, methanethiol smells like rotten vegetables.

Guaiacol: has the smell of smoke and spice.

Carbon dioxide is a volatile substance that does not affect the aroma, but does affect the thickness of alcohols.

Baking process

1. Drying

When the raw bean is heated, the water vapor in the raw bean will evaporate, and the raw bean will turn white from green at about 135 degrees Celsius.

two。 dehydration

As the heating goes on, the raw beans change from green to light yellow, and when the temperature reaches about 160 degrees, the aroma of baked grain will be emitted. After continuous heating, the beans turn light brown.

3. An explosion

After about 190 degrees dehydration is completed, a burst occurs due to the rupture of the cell wall caused by internal thermal expansion, and a series of thermal decomposition reactions occur inside the beans, in which the caramelization brings the sweetness, dark brown and mellowness of the coffee beans. the explosion lasts about a minute and a half.

4. Second explosion

As the heating goes on, it enters the "second explosion", and a more violent reaction will take place inside the bean. And give off a lot of heat. With the end of the second explosion, the raw bean has basically turned black, the bean body has expanded to 1.5 times that of the original, the surface is oily, and the weight is reduced to 12%, about 20%.

5. Stop it

Baking usually ends about a minute after the second explosion, when the temperature reaches 200 degrees, which is a deep French or Italian baking, which may cause the coffee beans to ignite spontaneously when the temperature exceeds 230 degrees Celsius.

Main roaster brands

1. Probat in Germany

Old brands, large and medium-sized machines, semi-automatic, full-automatic various types, sophisticated design, high price.

two。 Japan fuji-royal

The products of fuji Company of Japan also have good performance, but the same price is not cheap.

(3) brief introduction of Taiwan Yang family roaster

Yang family machine Pegasus brand coffee roaster, the classic model is stable and practical. The cast iron inner pot makes the boiler temperature stable, the heat accumulation is good, and the coffee beans are heated evenly. Taiwan's Yang family Pegasus machine boilers are all made of cast iron, and the thickness of the boiler wall is up to 12MM, which is very rare in China, the United States and Japan.