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How to Roast Decaf Coffee

It looks and smells a little different. But does decaf coffee roast differently from non-decaffeinated coffee?

Yes. A little. 

Discovering the best roast profiles for different types of coffee can be a challenge. But understanding why some coffees roast differently can be the key to creating a roast curve that can turn good coffee into fantastic coffee. 

It all starts with the journey of the bean. 

Read more about why Decaf coffee roasts a little differently from non-decaffeinated coffee and learn how to get the best out of your Swiss Water Decaf roasts. 

Green Coffee

Decaffeinated green coffee looks different to non-decaffeinated coffee. The beans are often slightly darker in colour and more matte in finish. 

This is ok.

These differences signify only that the coffee has been through a slightly longer journey. And will need to be treated a little differently as a result. 

Decaffeinated coffee, whatever the process, has gone through two additional stages to non-decaffeinated coffee. The Swiss Water Decaf process, for example, involves the further steps of rehydration and drying, which are essential in removing caffeine and stabilising the coffee for roasting.

This longer journey creates differences in the coffee’s appearance, structure and moisture volatility. Therefore, it is essential to keep this in mind when developing a roast curve for Swiss Water Decaf coffee. But understanding how this changes the coffee can help us imagine how it will react in the roaster, enabling us to develop the most appropriate roast curve.

Charge Temperature & Drying Phase

As we learned, Swiss Water Decaf coffee’s structure and water availability are slightly different from non-decaffeinated coffee due to the rehydration and drying processes. 

The different bean structure makes decaffeinated coffee more susceptible to scorching at the beginning of the roast. Whilst the altered water composition can hinder flavour development later on. 

To avoid scorching, ensure you start the roast with a lower charge temperature than you would with non-decaffeinated coffee. The gentle heat application will mitigate against shocking the coffee’s more delicate structure. 

As the coffee progresses through the drying phase, try to keep the energy low to maximise moisture availability. This will come in useful later during first crack, maximising flavour potential in the coffee. 

Maillard Phase

As we know, the colour of decaf coffee is a little different to non-decaffeinated coffee – generally a stage further along the chain. Therefore it’s important not to rely too much on colour change to assess development. 

Instead, use roast software, temperature and smell as indicators for roast development. For example, Swiss Water Decaf still exhibits comparable aromas as non-decaffeinated coffee and displays similar thermocouple readings when transitioning through the different roast stages. 

As the coffee passes through the Maillard phase, experiment with incremental heat introduction to maximise what water is available in the coffee. Depending on your set-up, this approach might be the best way to utilise the moisture you preserved during the drying phase for maximum flavour development leading into first crack. 

First Crack

For Swiss Water Decaf, first crack is often quieter and more gentle than non-decaffeinated coffee. Mainly this is due to the limited moisture availability, which creates lower pressure in the bean. So, listen closely. Or use your roasting software to spot first crack on the ROR (rate of rise).

As Swiss Water Decaf travels through first crack, don’t be surprised to see a sudden rise in the ROR due to the volatility or lack of moisture content – especially if you have increased the energy on the lead-up. So be prepared to put on the brakes and quickly lower the heat after first crack to stabilise the ROR, stretch the development stage, and bring out the sweetness and flavour in the cup.  

Development Phase

We find Swiss Water Decaf tastes more complex, sweet and balanced with a longer DTR (Development Time Ratio). Typically, reducing the energy after the first crack allows for a stretched development phase and enhances flavour, preventing roast defects in the later stages of the roast.

Keep in mind that the coffee’s colour towards the end of the roast will still maintain that darker appearance. So watch your temperature readouts and roasting software, as well as use your sense of smell, to determine the best time and temperature to bring the roast to an end.

Roast Development Analysis

Even though the exterior colour of roasted decaffeinated coffee may be darker than that of non-decaffeinated coffee, there are still some ways to assess roast development accurately. 

Firstly, the interior colour of Swiss Water Decaf should be the same or similar to that of non-decaffeinated coffee. Using a colour meter to assess the interior colour of the roasted beans is a great way to evaluate development in your decaf roasts. 

Alternatively, using solubility as a measurement of development is also a good analysis method. All you’ll need is a refractometer and some time at the cupping table to calculate the TDS readings on your decaf and non-decaf roasts. 

It is worth keeping in mind that roasting loss works a little differently with decaffeinated coffee. As some of the coffee’s components are removed during the decaffeination process, such as caffeine, the roasting loss on decaffeinated coffee will be slightly lower than non-decaffeinate coffee. 

Of course, there is no better way to assess your decaf roasts than by tasting them! Roasting for flavour is the best way to ensure you get the most out of your Swiss Water Decaf coffee. So make sure you taste every roast to get to know your Swiss Water Decaf and adjust your roast profiles as needed. 

Embrace the Difference

Swiss Water Decaf is a little different. But by embracing these differences, paired with a bit of time and experimentation, you can get the most out of your decaf roast.

To learn more and read the resources used for this article, follow the links below.

Swiss Water Decaf: Roasting Decaf Coffee

SCA: Optimizing the Roast of Decaffeinated Coffee