Understanding the stages of the roast is fundamental to successful roasting.
Tom has been talking about this for a while … that we don’t have enough basic information about color changes in roasting. Understanding the stages of the roast is fundamental to successful roasting; it is hard to emphasize it enough. He shot a macro-image video under very strong light to show color changes during the roast process.
He emphasizes the development of each stage (in both air and drum roasts) and what you can expect to see and hear. The end of the roast is crucial; in the 15 to 30 seconds from first crack moving toward After First Crack, a roast reaction around 440 to 450 degrees that is distinguished by a snapping sound. Second Crack is the second audible clue the roaster-operator receives about the degree-of-roast, following First Crack. Whereas, your roast very quickly goes from City+ roast is an ideal roast level that occurs roughly between 425 and 435 degrees Fahrenheit in many coffee roasters with a responsive bean probe where First Crack starts in the 395 to 405 degree to Full City+ (and beyond!).
Make sure to pull up a stool and pay attention to the end of the roast not matter what method you use.
I’ve added this video to our Visual Guide to Roast page as well. Hope you find it useful. – Maria