Roasting the Perfect Bean

Coffee is an extremely versatile cup of drink. The roasting process of the coffee beans is a chemical process where the green coffee beans are transformed into roasted beans that emit a unique aroma and taste. This page will go over the roasting chemistry of coffee and how it impacts the appearance and taste.

roasting-coffee-beans.jpg

Roasting is the most important factor that helps coffee develop its complex flavour. During the roasting process, the beans undergo many complex chemical reactions that change the beans physically and form different substances that are responsible for its taste.

The Maillard Reaction

gettyimages-151993684-2000.jpg

This process begins at around 150°C/302°F. The heat causes a chemical reaction between the carbohydrates and amino acids in the beans that produce changes in colour and flavour.

Reducing Sugars and Amino Acids

Maillard reactions happen between a reducing sugar and an amino acid. A reducing sugar is any sugar that has a free aldehyde or ketone group. These groups contain an oxygen atom with a double bond joining it to the carbon chain, which can easily react with amino acids and many other compounds.

Aldehydes-and-ketones.jpg

The Reaction

When they react together, the nitrogen in the amino acid bonds to the carbon chain of the sugar forming glycosylamine. Due to glycosylamine instability, it reacts again in one of three paths: either losing more water molecules to become caramel-type molecules, breaking down into short chain molecules, or reacting again with more amino acids. 

Glycosylamine.jpg

All three products of these reactions can react again with amino acids to form melanoidins, which are dark brown compounds that provide a lot of the colour in coffee. Melanoidins also play an important role in the formation of crema, which is the brown froth that rests on top of a shot of espresso.
 

The rate of Maillard reactions becomes significant in coffee roasting from about 140° C (284° F). Above 170°C (338° F), caramelisation kicks in and starts to use up the remaining sugars. 

The Outcome

The different possible paths these reactions can follow allows for the formation of a huge range of flavour compounds. The reactions can generate reactions between smaller molecules, generating floral, fruity, and caramel aromas.

Our Roaster

1/4

At Third Culture Coffee we use 2KG Solar electric roaster to our coffee. Unlike other commercial roasters, because our roaster is powered by electricity, our roasts have a initial temperature and final temperature.

3 Types of Coffee Roast 

At Third Culture Coffee, we roast and sell three different roasts of coffee. Each roast of coffee has its own unique identity. The most distinct difference between the three roasts of coffee would be the time the beans are roasted. Our darker roast coffee is roasted for a longer period because of its higher final temperature. The tables below will give you a deeper look into each roast.

IMG_9069.JPG
IMG_9069.JPG

Light

Roasting Temperature

Initial:155°C

Final:176°C

Taste

Sweet, Tangy

Look

Acidity

Light Tan

High

Medium Roast.JPG

Medium

Roasting Temperature

Initial:155°C

Final:180°C

Taste

Balanced flavour with slight sweetness

Look

Medium Brown

Acidity

Balanced

Medium Roast.JPG
Dark Roast.JPG

Dark

Roasting Temperature

Initial:155°C

Final:184°C

Taste

Bitter, smoky

Look

Acidity

Low

Dark brown,

Oily

Surface