How does the roast level impact the caffeine content in coffee?

The relationship between roast level and caffeine content is nuanced, and choice C accurately reflects this. When coffee beans are roasted, they undergo a process called pyrolysis, which changes their chemical composition, including the caffeine content.

Darker roasts, which are roasted for a longer time and at higher temperatures, tend to lose some of their caffeine content when compared to lighter roasts by volume. This is due to the longer exposure to heat, which can result in the breakdown of caffeine and a reduction in its concentration. Thus, while the total caffeine content in the beans does not dramatically decrease, the beans' density changes; dark roasts are less dense than light roasts because the roasting process causes them to lose water and expand.

As a result, if measuring by volume (such as a tablespoon), darker roasts may yield less caffeine than lighter roasts. However, if weighing an equal mass of ground coffee, the caffeine content would be more comparable. This nuance is crucial for understanding why lighter roasts contain more caffeine when measured by volume compared to darker roasts.

This information is beneficial for baristas and coffee enthusiasts alike, as it aids in understanding how brewing methods and bean selection can affect the flavor and caffeine experience of brewed coffee.