First Crack and Moisture Release

First crack can be described as the point of Peak Rate of Moisture Release: the moment when moisture release from the coffee reaches its maximum rate. This framing was shared as a quote attributed to the Ikawa website. source

Ikawa’s quoted material says this peak moisture-release point is tracked on the Pro100x and used to mark first crack objectively, automatically, and precisely. This should be treated as Ikawa/Pro100x-specific information unless separately verified for ROEST machines or other roasters. source

The same quoted source says the peak moisture-release point aligns very closely with where people mark audible first crack, and that this alignment was tested in a blind trial over 40 coffees. source

Practical Note

For ROEST users, this provides useful context for thinking about first crack as a physical moisture-release event, but it does not by itself establish that ROEST can automatically detect first crack using the same method or sensor approach as the Ikawa Pro100x. source