Page 88 - #53 English

CTI Class

Article by Coffee t&i Thailand
Photo by SCAA
Flavour Development

Several reactions occur inside coffee bean during roasting. The beans transform physically and chemically, resulting in the
change in colour from light green to brown and the development of the flavour. Some flavours are broken down while some are
developed into the desire flavour. A good roaster need to understand these changes to get the taste he wants, and this edition of
CTI brings you the basics of flavour development from Mr. Sarawut Premchit, SCAA Roasting Specialized Instructor from Intercof
Co., Ltd.
Before the beans go into the machine, the machine should be set at the right initial temperature, or the Charge Tempera-
ture (CT). The temperature will drop after the beans are loaded into the machine. The time taken to reach the lowest point of this
drop in temperature is called the turning point, in which the temperature will rise back after this point. A good roasting machine
would give you a guide on the charge temperature and the suggested volume of the beans.
For example, a 5 kg batch should have the charge temperature at 200°C and 1 minute turning point. But if the volume
changes to 3 kg, the turning point may reduce to 50 seconds at charge temperature of 200°C. In this case, charge temperature
should vbe reduce in order to maintain the turning point at 1 minute.
CT has a huge effect on the coffee beans. Incorrect setting could lead to roasting defects like facing, scorching, and tipping
which could introduce burnt or smoky flavours to the beans. These defects can be observed by eyes if your CT is too high.

Facing Tipping Flavor caused by roasting defects

160 - 200 °C during which caramelization occurs (cara-
melization of Sucrose, Fructose, Glucose, Maltose, etc.).
After this point, Flavour Development phase kicks in and
determine the coffee flavour.

Flavour Development

Fast Roast: High acidity
Example After the first crack at 195°C at the 8
th
minute, if we continue to roast the beans to 210°C until
the timer says 9 minute 50 second, we will have the devel-
opment time of 1 minute 50 second and a fast roast coffee.

After turning point, the temperature rises to 193-195 Ideal Roast: Balanced acidity and sweetness and body
°C where first crack occurs, past the drying phase where the Starting at the same first crack (195°C at 8th
beans change from green to yellow, and past the point of Maillard minute), continue roasting to 10 minute 30 second. The
reaction (around 154 °C) which turns the beans from yellow to development time here is 2 minute 30 second, but we have
brown. Mailard reaction or browning reaction breaks down sugar to decrease the heat and maintain the temperature at 210
(Glucose,Fructose, Maltose, etc.) until the temperature reaches °C throughout the development time. The colour will be
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