I know I have stated on a past blog post that light roasts have more caffeine content than dark roast, but I want to take the time to clarify that statement and add a little more context to this caffeine myth. The real answer is: it depends.
If a person were to say that dark roast has more caffeine than a light roast they could potentially be correct. However, if another person says light roast has a higher caffeine content than a dark roast then they could possibly be correct in their statement. To be fair there is little difference, but there is a difference. That difference is decided on how the beans are being scaled.
Why is that?
When coffee is roasted many people believe that the longer a bean is under intense heat the more the caffeine is burned out of the coffee. A study done by Scribbler’s Coffee Company revealed that caffeine content isn’t affected to greatly at temps less than 600 degrees. So what that means is if you take the same two coffee beans and measure the caffeine content prior to roast and then after roast there will not be much of a difference between a light roast and a dark roast.
So why is the answer ‘it depends’?
When coffee is roasted there is a certain amount of moisture loss. For a lighter roasted coffee there will be less moisture loss resulting in a higher density. Hence the opposite for darker roasted coffee, less density because there is greater moisture loss. Also during roasting beans tend to swell, or balloon. The lighter the roast the less ballooning. The darker the roast the greater the ballooning. What this means is that depending on whether or not the coffee is measured by volume or weight will determine the amount of caffeine, though there isn’t going to be a huge discrepancy there either because that is decided by a few beans. Technically speaking, however, one will be greater than the other.
For example, if we measure a dark roast by sheer volume it will take less dark roasted beans to fill a particular volume than it will a light roast because the size of a dark roast of the same bean tends to be larger than a light roasted version. Therefore, a light roast will have more caffeine because more beans are required to fill the desired volume. By weight the opposite is true. A light roast is more dense and heavier than a dark roast. It requires less light roasted beans of the same coffee to achieve the desired weight than it does if they were dark roasted. That would make the dark roast produce a higher caffeine content.
Another point of contention for what has higher caffeine content is fast. The taste of the coffee does not determine the amount of caffeine present. People often ask for the strongest coffee they can get thinking that the stronger taste means higher caffeine. Taste does not equate to how much caffeine there is because, as we just pointed out, how we measure the coffee decides that factor. Additionally, different coffees have varied amounts of caffeine, and the kind of varietal the coffee is a deciding factor as well. A Robusta varietal and an Arabica varietal vary greatly in caffeine content, Robusta being nearly twice the amount of caffeine. But who drinks Robusta!
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