The Essence of Coffee, Bean Roasting

Coffee Roasting Methods

Drum Method

In drum roasting, beans are roasted as they rotate inside
a cylindrical drum. The raw beans are roasted as they are
heated inside rotating drums, and this process is also
known as direct flame roasting.
It allows for an intuitive perception of coffee taste and aroma,
and the machines used are economical and widely used

Hot Air Method

Hot air roasting, on the other hand, circulates hot air
among the beans to roast them. It enables uniform roasting
within a short period, making it suitable for
roasting large quantities of beans.

Coffee Roasting Process

Drying Phase

The drying stage is the first stage of roasting, in which
the drum is heated to remove moisture from
the coffee beans and lighten them. During this process,
the first cracks occur in the coffee beans, making their
acidity, bright color, and light body stand out.

In the drying stage, the roaster adjusts variables such as
roasting time, heating temperature, and drum speed
to proceed with the roasting. Additionally, conditions must
be set according to the characteristics of each coffee bean.
Improper drying conditions can result in loss of unique aroma
and flavor, so roasters must carefully control these variables.

pyrolysis

The pyrolysis step is a very important step in
the roasting process. At this stage, proteins and sugars
interact to cause chemical changes, releasing carbon dioxide
,and producing melaninin, which is responsible for the taste
and aroma of coffee, and various aromatic substances.

During this process, changes in color, shape, scent,
and sound occur, and at high temperatures above 150 degrees,
ingredients such as sugars, amino acids, and peptides
are decomposed by heat, causing various chemical reactions
to occur. This is a very important step because the combination
of chemicals formed at this stage determines the aroma
and taste of the coffee beans.

cooling

The cooling stage is the process of quickly cooling down
the coffee beans after they have been sufficiently roasted.
This step begins immediately after the beans leave the roasting
machine. It is important to quickly lower the temperature of
the coffee beans to suppress the chemical reactions
that continue to occur inside the coffee beans.

The cooling step balances the properties of the beans
after the roasting process is complete.
If cooling is not done sufficiently, a chemical reaction may
continue inside the coffee beans, damaging the taste
and aroma of the coffee beans. Additionally, this step quickly
removes any moisture remaining in the coffee beans,
reducing the risk of mold or spoilage.
Therefore, the appropriate cooling stage is very important
to maintain the unique taste and aroma of coffee beans.

Coffee roasting reaction

Maillard Reaction

Various flavors emerge during the coffee roasting process,
largely due to the Maillard reaction occurring in the beans.
This chemical reaction involves the combination of
amino acids from the bean's protein with carbonyl compounds
from sugars, forming new molecules.
These newly created molecules contribute to
the diverse flavors found in coffee,
such as the roasted grain and sweet caramel aromas.

Caramelization

Another chemical reaction occurring during roasting is
caramelization. This reaction occurs slightly later than
the Maillard reaction. Sugars encounter heat, oxidize,
and cause the bean's surface to turn brown, producing
distinct aromas. Despite the name, caramelization actually
decreases sweetness and increases bitterness in the coffee.