Making good coffee or good extraction, the correct scientific term means balancing several variables.
In addition to the method of preparation and the proportion of coffee and water, you should keep in mind the roasting profile of the coffee, as if you prepare a lighter roast coffee and a darker roast coffee in the same way, you will have different results that can need some adjustments to have a well-balanced cup.
Variations Of Coffee Roasting
We know that the type of coffee roasting affects its taste in the cup. The same coffee, in different towers, will taste differently. This happens because the longer the coffee stays in the roaster, the more natural sugar the bean is consumed. Therefore, the darker the coffee roasts, the less sweetness it will have.
In general, lighter towers keep the flavours of coffees better, and this profile highlights floral and citrus notes. And those in the darkest towers, these more delicate notes can be dominated by the most chocolate and nutty tones.
Why should we extract coffee differently with varying roasting?
A perfect cup of coffee depends on the right level of extraction.
We talk about extraction because making a coffee is a process of extracting soluble compounds in roasted and ground coffee. As we make coffee with hot water, hundreds of compounds are extracted, resulting in the cup of coffee we drink every day.
The compounds responsible for the fruity notes and acidity are extracted first following the sugars that give the sweet taste. The compounds responsible for the bitterness are extracted later. Thus, if coffee is under-extracted, it can taste sourer because the sugars did not have a chance to enter the drink. And an excessively extracted coffee can have a lot of bitterness.
As the lighter roast grains are less porous than, the darker ones, the compounds will be extracted more slowly. For this reason, light roast coffees are generally used more in methods where water stays longer in contact with coffee, instead of faster methods such as espresso.
So if you make the same lighter and darker roast coffee in exactly the same way, you will get a different result in the cup.
How to adjust your recipe for a different roasting profile?
There are some variables that you can adjust to make your coffee in different towers; they are:
There is no exact temperature you should use, but a temperature range (between 90ºC-96ºC, suggested by SCA) that also depends on the method of preparation. The higher the temperature, the faster the extraction will be. Some compounds will never be extracted at very low temperatures, so the cold brew tends to be sweeter and without bitterness.
So, if you are preparing a darker roast coffee, try using the water at a slightly lower temperature to avoid over-extraction and reduce the bitter taste. If you are using a lighter roast than usual, use slightly warmer water to speed up the extraction.
Keep this in mind when choosing a preparation method. For example, to make an espresso, where extraction is super fast, perhaps light roasting is not the best choice.
It can be very interesting to make coffees with different towers, varying the grind, water temperature and preparation time, and see how it results in the cup.
But consider that over time, the coffee loses some of its flavours. Oxidation and degassing cause coffee to lose some oils and compounds that contributes to body, aroma and flavour. Therefore, after opening the packaging of your coffee, try to consume it within a month and store it correctly, away from light, moisture, heat and air.