Surprisingly to many, roasting coffee is a precise and creative art. In actual fact, when roasting you are actually undergoing a complex cooking process. Coffee roasting equipment can vary hugely, from high tech commercial units costing hundreds of thousands to a simple pan on a stove top at home.
The truth is, there are endless ways to produce your perfect coffee and there is no right or wrong answer, it simply comes down to what you prefer.
Whichever way you do it one thing remains the same, heat. When heat is applied to the coffee bean, hundreds of chemical reactions simultaneously take place, much the same as when you cook food. This is why professional roasters have precise and accurate recipes (otherwise known as ‘Profiles’). Profiles are not just about which type of beans are blended together. Many of the same compounds present in the raw foods we cook are also present in raw green coffee, and they metabolise the same way under applied heat. This is why our decades of knowledge in cooking food and handling coffee helps us create fantastic flavours from our beans.
Roasting can vary hugely depending on the roasting methods, types of machines used, environmental factors and the type of bean selected. The profile is actually the name that is given to the line graph that shows how the beans heat up in the roaster over time. At The Lost Barn we use complex software to help monitor and manage this process, ensuring consistency in everything we do. By following a profile accurately, we are able to reproduce a good recipe over and over again.
There are four clear stages of the roasting process. During these stages, it’s the roasters responsibility to see that every batch progresses the way that it needs to through each stage so that the end result is nothing other than fantastic quality and full of flavour.
Learning to recognise the progression of the roast and the different stages is crucial towards taking control of the flavour development. In essence different roast profiles will create different flavours in the cup. Look out for the types of roast and bean within the product information in our Shop.
Drying / Colour Change
The first few minutes of the roasting process is called ‘Drying Phase’ or ‘Colour Change’. Before the bean is roasted it is a raw green/yellow seed that is virtually odourless, or at times having the smell of wet grass or smelling slightly fruity.
These raw seeds are deposited into a pre-warmed roaster referred to as a ‘Charge’. During the first few minutes the seeds heat up rapidly until reaching equilibrium point with the inside temperature of the roaster. You should also notice aromas of grass or hay. This is where the ‘Turning Point’ or ‘Turnaround’ happens and is the launching point for the entirety of the roast.
Pre First crack
This stage isn’t necessarily commonly known or recognised, however over the recent years it has started to gain more interest and importance. From around 6 minutes into roasting up until First Crack, the bean will go from a yellow colour to a brown, indicating that chemical reactions are taking place, and lots of them! If left to progress, ultimately the coffee will end up a flavourless, black piece of carbon - otherwise known as charcoal!
Progression here is where the roaster really takes control of the final product and flavours produced.
In this next stage the bean surface begins to dry out and becomes wrinkled with steam rising from the bean producing fragrant baking and toast aromas. As the name suggests, it is at this point that the audible sound of the "first crack" is heard. This is where sugars start to caramelise, water escapes in the form of water vapour and the pressure build up inside the coffee seeds cause the cell structure of the bean to break open or ‘Crack’.
It can be said that at this point the roasting could be considered complete. However, experimenting beyond this point will give you variations in style and flavours. It is also true to say that the roasting development of the bean takes place across the entire profile.
During this phase the roaster is at their most active managing the heat within the roaster. Controlling the heat may seem a simple task, however various beans can behave in different ways, consuming or exhaling heat in ways that make it difficult to manage. It’s here that the complex software used by many roasters, and by Lost Barn, comes in to play.
This stage is where either a ‘light’ or ‘dark’ roast is produced, depending on the ending ‘drop temperature’ combined with the total roast time, or more commonly the time from ‘First Crack’. This variation happens because as the coffee progresses through the phase, sugars begin to further caramelise and eventually start to burn-off, leaving behind carbon producing a noticeable smoky flavour in the cup.
If you choose to continue roasting after this point the heat input will cause the oils to migrate to the surface, where they quickly begin to evaporate (taking coffee flavour with them). A light roast, in contrast, has a dry bean surface and perhaps a ridged texture.
In comparison, light roasts are usually brighter, more acidic, and more fruity than darker roasts, which range into nutty, chocolaty, or smoky flavours.