There is a complex journey coffee takes before it becomes the flavoursome beverage we know and love. At the heart of this journey is the coffee roasting process. Coffee roasters go through this process meticulously to ensure a great cup of coffee.
This article will guide you through the various stages, equipment and techniques involved in transforming raw green coffee beans into the aromatic beans that make each cup so delicious.
1. The Green Bean
At the very beginning of the coffee roasting process is a green, unroasted seed. These green coffee beans are typically (Remove ‘typically’) sourced from coffee-producing regions across the world, such as Peru. They are chosen based on factors such as origin, flavour, altitude grown and flavour quality. The green beans depending on how they are processed can have a grassy or even a fruity smell, completely unlike the rich aroma we associate with coffee.
2. Coffee Roasting Machines
The transformation from green bean to roasted coffee could not be done without the key player: the coffee roasting machine. These machines come in various types, from traditional drum roasters to modern fluid bed roasters. Each has different characteristics and a unique way of applying heat to the bean. How this heat and time is applied influences the final flavour profile.
3. Coffee Roasting Profiles
Altitude, coffee variety, agricultural management, bean maturity and processing shape the coffee’s personality. Roasters use profiles to tailor the coffee roasting process to bring out the best in each bean. A roast profile consists of temperature and time settings. These factors can significantly impact the flavour and aroma of the final coffee.
4. The Roasting Process
Once the green beans are loaded into the machine, the magic begins. As the beans heat up they go through a series of transformations that give coffee its distinct characteristics. This process is divided into stages, each stage playing a crucial role but combined develop the aroma and taste to create the flavour.
5. The Drying Phase
When roasters receive the green beans, they have a moisture content of between 8% and 12%, so they must be dried before the roasting can start. This is the initial phase that takes place within the roasting machine. As the beans absorb heat, they dry and turn green to yellow. This typically takes 4-8 minutes.
6. The Browning Stage
From 160 ⁰C the coffee starts to smell like toasted bread and hay. This is when the aroma precursors are starting to convert to aroma compounds. Even though the browning stage is after the drying stage, drying continues during the browning stage. At this stage the Maillard reaction starts, responsible for browning. Hundreds of different aroma and colour compounds are created in the Maillard reaction. This is the stage when the roast is slowed down to ensure flavour development.
7. The First Crack
The’ first crack’ is one of the most critical moments in the coffee roasting process. This is when the beans audibly crack and it marks the start of the development time. It happens at approximately 196 degrees Celsius. During this phase, the roaster will determine the end time and end colour. The time taken at this stage to the end colour, determines the ultimate flavour in the cup.
8. The Second Crack
After some more roasting time, there will be a second audible crack. The temperature will have risen to approximately 224 degrees Celcius now. This indicates that the roast profile is getting darker. Roasters will need to monitor the beans carefully at this stage to ensure they result in the exact roast level desired. They will look out for factors such as size, colour, and surface texture.
9. Cooling and Resting
Once the desired roast level is achieved, the beans must be rapidly cooled to stop the coffee roasting process. Cooling locks in the flavours that were developed during roasting, this is done on a cooling tray. After this, the beans have a resting period in which they release natural gases.
10. Brew and Enjoy
The final stage of the coffee roasting process is down to you. Brew the beans with your coffee machine, add extras such as milk and enjoy!
What is the ideal roast level for an espresso?
Traditionally, an espresso is made with dark-roasted coffee. Espresso’s are small in volume and very concentrated. So, the strong flavour of dark roasts is ideal.
How long should coffee beans rest after roasting?
This depends on the roast level of the beans. Dark roasts should rest for 1-5 days, medium roasts 5-7 days and light roasts 10-14 days.
How do I store roasted coffee beans?
The best way is an airtight container. However, there are many other tips on how to store coffee beans.
How long is coffee fresh after the coffee roasting process?
After the beans have had their resting period, they will stay fresh for 2-3 weeks. After this, you may be unable to pick out the flavour notes.
What is a French Roast?
French roast is one of the darkest roasting levels. To achieve this, roasters roast the beans longer after the second crack. The flavour is bold and smoky and has very little acidity.
The coffee roasting process is a methodical and intricate journey. Roasters put great care into ensuring the result is high-quality, great-tasting coffee. Knowing what goes behind each cup, helps us appreciate it much more.
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