Coffee Data Science

Double Coffee Roasting to Save a Mistake

A short story of correcting a mistake

Robert McKeon Aloe
2 min readSep 2, 2022

In the past 8 years, I have roasted around 500 roasts on my Hottop. I have only messed up a few by dropping the beans too soon or too late. One time, my son hit the button, and the beans hadn’t gone through the first crack. So I put them right back in, and the roast turned out okay.

This situation happened again, but it was my fault. I had been working on a process for modifying green beans using Koji rice. I had my beans prepared, but it was hard to determine the first crack. I dropped the roast too soon.

All images by author

The beans were clearly under roasted, and I knew I wouldn’t have a good experience drinking or extracting the coffee. I measured density to be sure, and the density was 0.63 g/ml. The maximum density in roasting I have seen is around 0.53 g/ml for a light roast.

So I took a risk knowing I would either have a severely under-roasted coffee, a over-roasted, or maybe something better.

Second Roast

I threw them back in, and I hoped for the best. I paid close attention, and I let them run a little longer because of the Koji rice processing.

The new density was 0.44 g/ml, and the color looked a lot better.

The beans turned out to be fantastic. It was a relief to know that I could correct such a mistake, but that’s not always a given. You never know if you don’t try.

If you like, follow me on Twitter, YouTube, and Instagram where I post videos of espresso shots on different machines and espresso related stuff. You can also find me on LinkedIn. You can also follow me on Medium and Subscribe.

Further readings of mine:

My Future Book

My Links

Collection of Espresso Articles

A Collection of Work and School Stories



Robert McKeon Aloe

I’m in love with my Wife, my Kids, Espresso, Data Science, tomatoes, cooking, engineering, talking, family, Paris, and Italy, not necessarily in that order.