Roast

       For me , Coffee roasting is the most difficult but the most interesting process.   To learn roasting well , we need not only knowledge but lots of experiences. For instance, to get a professional Batista license , it required everyone to roast more than 800 times . This week , I am going to tell you that coffee roasting is more than putting beans in the machine , it's a process of several chemical changes.

We can separate the process by the temperature .

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1. Under 160 ℃

During this period of time , the beans absorb heat , lose about 10% of water , and the color shifts to yellow when the temperature is near 160~165℃

2. 160~190℃

 .  Beans are usually heated up about 10℃ per minutes. In these three minutes , it need more heat source to enhance the Maillard reaction (梅鈉反應) and the Cancellation reaction (焦糖化反應).  We'll see the beans turn into the color of light brown .

3. Around 200℃

     "First Crack " will happen at this time ,  the obvious "first crack sound " means that the moisture of the beans are being evaporated and we'll see the size of them getting larger .  If we want the light-roasted coffee with more fruity flavors , roasting usually end after 45 seconds to 2 minutes of first crack.

4. Around 220℃

Second crack , the sound represents the structure of coffee starting to collapse. Not only the color will become black but the oil will appear , making the beans looks shiny .  The well-known Mandheling and the other Italian coffee are often roasted to this degree. All of the coffee shouldn't be roasted after 2 minutes of second cracks , or they'll get carbonized, even combust. 

In fact , the words above is just the basic  knowledge above . To master  roasting , experiences play an important part . Because the weather , the temperature , the humidity at the moment we roast matter a lot. 

Next week , I'll give a brief introduction of each degrees of roasting .