First Crack & Second Crack¶
First Crack An audible popping sound that occurs during roasting at approximately 196-205°C (385-401°F) when pressure from steam and CO2 inside the bean causes the cell structure to fracture. Marks the beginning of light roast territory. Sounds like popcorn popping. First Crack Start The moment when the first audible pops begin. Often used as a reference point for roast timing and development. Beans begin rapidly expanding and changing from greenish to tan/light brown. First Crack Peak The period of most intense cracking activity, typically 30-90 seconds after first crack starts. Maximum popping frequency. Critical decision point for light roasts. First Crack End When the popping subsides to occasional pops. Beans are light brown and still developing. Roaster must decide whether to stop (light roast) or continue to medium/dark. Between the Cracks The quiet period between the end of first crack and beginning of second crack. Development phase where sugars caramelize and body increases. Medium roast territory. Can last 1-4 minutes depending on roast profile. Second Crack A second series of pops occurring at approximately 224-230°C (435-446°F), quieter and faster than first crack. Sounds like Rice Krispies or crinkling cellophane. Indicates cellular structure breaking down further, oils migrating to surface. Marks beginning of dark roast. Second Crack Start The initiation of second crack popping. Bean surface begins to look oily. Acidity dropping rapidly, roast flavors developing. Critical decision point for medium-dark to dark roasts. Beyond Second Crack Roasting past second crack into French, Italian, or Spanish roast territory. Beans become very dark, oils prominent, structure fragile. Risk of fire if taken too far. Rate of Rise (ROR) The speed at which bean temperature increases during roasting. Measured in degrees per minute. Critical for controlling when first and second crack occur. Declining ROR throughout roast creates optimal development. Development Time Time spent roasting after first crack begins. Typically 15-25% of total roast time. Crucial for flavor development. Too short creates underdeveloped coffee; too long creates baked flavors. Development Time Ratio (DTR) The percentage of total roast time spent in development (after first crack). Specialty coffee typically aims for 15-25% DTR. Higher ratios develop sweetness; lower ratios preserve acidity. Crack Temperature The bean temperature at which first or second crack occurs. Varies with roasting approach but typically 196-205°C for first crack, 224-230°C for second crack. Used to gauge roast progress.
Related Notes: - Coffee Terminology MoC