Coffee Alliance: The Coffee Roasting Process
By Naz Oozeer – General Manager of Operations
Coffee beans are transformed from green to brown through the roasting process, which can affect their flavour. There are three main stages in roasting: the drying stage, browning stage, and development stage.
- Drying Stage: The coffee beans, which contain 8-12% moisture, are roasted to drive out the moisture. Care must be taken to avoid burning the beans by controlling the heat. As the beans lose moisture and undergo chemical reactions, the roaster operator reduces the energy input, allowing thermal momentum and exothermic reactions to continue the roast.
- Browning Stage: The coffee starts to smell like toasted bread and hay as it reaches around 160°C. This is when the aroma precursors start converting to aroma compounds. The Maillard reaction, responsible for browning, occurs during this stage. The beans become exothermic, and reducing sugars and amino acids react to create different aroma and colour compounds, known as melanoidins, which contribute to the coffee’s flavour profile. The roaster operator reduces energy input as the coffee loses moisture to control the rate of temperature rise and avoid harsh flavours. The first crack, characterized by popping sounds, marks the end of the browning stage and the beginning of the development stage.
- Development or Roasting Stage: During the development stage, pressure builds in the cells of the beans due to remaining moisture, and steam is released, resulting in the first crack. This stage is crucial for the desired aroma compounds to develop. Care must be taken to slow down the roast during this stage to avoid smoky flavours and sharp acidity. The length of the development stage depends on the desired flavour profile and roast degree, typically ranging from 15-25% of the total roast time. Longer development time reduces acidity and increases body, while shorter time increases acidity and reduces body.Roast Degree: Roast degree is a crucial indicator of coffee flavour and can be determined visually, using a colour meter, or by tasting. Light roasted coffees tend to be more acidic with fruity and floral flavours, while dark roasted coffees are more bitter with flavours like caramel, toffee, dark chocolate, and roasted nuts.Roast Time: Total roast time and time for each stage also impact the coffee’s flavour. Faster roasts preserve desired aroma compounds but risk burning the beans. Longer roasts result in a mellow and rounded flavour profile as more flavour compounds are roasted off. The entire roasting process typically takes 12-20 minutes to achieve the desired coffee flavour.
At the Coffee Commune, we embrace the diversity of coffee flavours and brewing methods. We work with our customers to create their ideal coffee profile, whether it’s a daily dark roasted coffee or a fruity light roasted filter coffee. We are a community of coffee lovers, dedicated to helping our customers enjoy their preferred coffee flavours without any judgment or stigma attached to what is considered the “best” coffee.
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