“I like my coffee strong”… I’m sorry to say this, but what you’re saying and what you mean, doesn’t match up. Let me explain…
After learning about the way coffee grows (catch up here and here) and how it’s processed (also, here), you now know that there is a lot of time, energy and effort behind a single coffee bean. I’ve also mentioned that each coffee tastes differently according to its country of origin, varietal, process method…
However, there is yet another variant in the coffee equation. When the coffee bean is shipped to caffeine consuming countries, we obtain what is called “green coffee”. If you were to brew this green coffee, you would get a bitter and acidic beverage which you would not want to have. On that note, there are some countries and companies that have been experimenting with green coffee. It does not taste like the traditional coffee taste though.
In order to get that coffee taste, we need to roast the coffee. What roasting does to coffee is that it extracts the moisture out of the bean. This causes the bean to release the natural sugars, which are converted into CO2 gas and then caramelised (Maillard reaction). This happens with other foods, like meat or bread.
Coffee roasters have identified several stages that coffee beans go through. The most important are: first crack and second crack. These “cracks” sounds like when doing popcorn in the microwave. After this second crack, the coffee starts to burn.
There is a common misconception that the “darker” the coffee, the “stronger” it is. This is actually not true. Depending on how you brew the coffee, it will be more or less “strong”. You can use more or less coffee, water and time to brew it, and you will get different levels of strength in the coffee.
Now, when people say they like their coffee “strong”, I think they generally refer to the taste. And yes, it is true that if a coffee is dark roasted, the bitterness will be more intense.
This is because the sugars and fruity notes within the coffee bean are the lighter compounds and easier to extract. The more you roast the coffee, the more bitterness you’re going to be able to extract.
In terms of the caffeine, there isn’t really that much of a difference between a dark roast or a light roast. But there is, in terms of flavour, between burnt coffee beans and a specialty coffee beans 😉