Listening for first crack on a popcorn popper

14 Sep 2026

I roast 90 grams at a time in an air popper that cost less than a bag of good coffee. It has no controls at all, which turns out to be useful: the only thing I can change is how long the beans stay in after first crack.

For a washed Kenyan I aim for roughly 15–20% of the total roast time after the first pops. With a 6-minute roast that is about a minute. I write down three times for every batch: start, first crack and the moment I tip the beans into the colander.

K-1216%

K-1319%

K-1426%

Three 90 g batches of the same washed Kenyan, in minutes: drying and browning, development after first crack; the figure is its share of the whole roast

Batch	First crack	Drop	Notes
K-12	4:55	5:50	bright, a little grassy
K-13	5:05	6:15	sweet, blackcurrant, the keeper
K-14	4:50	6:30	flat, roasty

Colour fooled me twice: K-13 and K-14 looked almost the same in daylight, and tasted nothing alike.