Introduction to Coffee Roasting
Coffee roasting is the process that involves transforming green coffee beans into the aromatic, flavour-packed brown beans that we all know and love. During roasting, heat is applied to the green beans, causing them to change in colour, smell, taste and size. The process unlocks a range of complex flavours by triggering chemical reactions such as caramelization and Maillard reaction.
Caramelization: A chemical reaction that occurs when sugar molecules are heated. During coffee roasting, the heat breaks down the sugars in the bean, caramelizing them and creating desirable flavour compounds such as buttery notes and sweet aromas.
Maillard reaction: A chemical reaction that involves the breakdown of proteins and amino acids which then interact with reducing sugars to produce complex flavours and aromas such as toasted nuts and chocolate.
The goal of each roast is to reach the optimal temperature where desired flavours are developed while avoiding over-roasting or burning the beans. This requires precise control over the heat intensity and duration of the roasting process. Different roast profiles can help achieve different flavour characteristics including sweetness, acidity and body.
The Impact of Roast Level on Coffee Characteristics
Roast Profiles
During the roast cycle, moisture slowly evaporates from the coffee beans until it reaches around 395°F, which will cause an audible “first crack” in the bean. When the roast is taken to a much darker level, this build-up of CO2 will cause another physical and audible change at a higher temperature, which is known as “second crack”. Some of our darkest roasts reach second crack as they spend a longer time in the roaster and reach a higher temperature.
Light Roast
350-400°F
Taking place after the first crack, light roasts have interesting and surprising flavour characteristics, often enhancing the overall acidity of the coffee, while retaining the original characteristics of the bean.
Medium Roast
400-425°F
Before the second crack, medium roasts maintain a balance of acidity and body, resulting in a smooth and satisfying taste while developing cocoa and caramel notes.
Dark Roast
425-460°F
After the second crack, these beans are roasted to the highest temperature, bringing flavourful oils directly to the surface that begin to overshadow the original characteristics of the bean. The richness and fullness of body command attention, while the acidity is diminished.
Marble Roast
Mix of different temperatures
A blend of light, medium and dark roasts, the flavour profile of Marble Roast is interestingly complex but not too extreme as some of the strictly darker or lighter roasts can be.
Roasting for Sustainability
To roast our coffee, we use 35 and 70 kg Loring Smart Roasters. By using the Lorings, we are able to be more efficient and produce more consistent flavour profiles, while controlling the environmental impact. The 70 kg roaster uses up to 80% less gas than traditional roasters and is designed to minimize smoke emissions.
Cupping for Quality
Cupping coffee is the next important step in assessing the quality of the beans, usually done by a coffee roaster or a Q-Grader. This involves tasting and analyzing the aroma, taste and body of freshly brewed coffee in order to evaluate it for roasting. The purpose of cupping is to identify any defects and classify each sample as common, moderately specialty, or specialty grade.
When cupping coffee, several parameters are evaluated, including:
- bitterness and acidity
- flavour notes like fruitiness, nuttiness and aftertastes
- the body of the cup and whether it is pleasant with a balanced acidity that leaves no harshness on the palate
- the aroma and the absence of undesirable flavours
Test Your Knowledge
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