[Edit May 11 2019: If you would like to contribute to further the development of this application, or to a similar future application to measure roast colorimetry, you can do so on my Patreon page.]
[Edit April 25 2019: Please note this is not an iPhone or Android app, and I have no plans to release it as such. You can use your phone or any other camera to take pictures of your ground coffee, but then you need to install the application on either OS X or through Python (on any operating system) to analyze the data. Download the application package here.]
Today I would like to present an OS X application I have been developing for a few months. It turns out writing Python software for coffee is a great way to relax after a day of writing Python software for astrophysics.
When I started being interested in brewing specialty coffee a few years ago, one of the first things that irritated me was our inability to recommend grind sizes for different coffee brewing methods, or to compare the quality of different grinders in an objective way. Sure, some laboratories have laser diffraction equipment that can measure the size of all particles coming out of a grinder, but rare are the coffee geeks that have access to these multi-hundred thousands of dollars kinds of equipment.
At first, I decided to take pictures of my coffee grounds spread on a white sheet, and to use an old piece of software called ImageJ, developed by the National Institutes of Health mainly to analyze microscope images, to obtain a distribution of the sizes of my coffee grounds. This worked decently well, and allowed me to start comparing different grinders. Then Scott Rao made me realize that a stand-alone application that doesn’t need a complicated installation and that is dedicated to coffee would be of interest to many people in the coffee industry. Probably just the 10% geekiest of them, but that’s cool.
I’m hoping that this application will help us understand the effects of particle size distributions on the taste of coffee. I don’t think the industry really kept us in the loop with all the laser diffraction experiments, so hopefully we can help ourselves as a community.
If you are interested in measuring the particle size distribution of your grinder, then this app is for you ‒ and it’s free. I placed it as “open source” on GitHub, so if you are a developer, you are welcome to send me suggestions in the form of push requests (the developers will know what that means).
If you would like to get started, I suggest you read this quick installation guide, which will explain how to download the app and run it even though I am not a registered Apple Developer. Then, you can choose to either read this quick summary that will get you running with the basics, or this very detailed and wordy user manual that will guide you through all the detailed options the application offers you.
I would like to show you an example of what can be done with the software. Below, I am comparing the particle size distribution of the Baratza Forté grinder, which uses 54 mm flat steel burrs, with that of the Lido 3 hand grinder, which uses 48 mm conical steel burrs. I set both grinders in a way that produces a similar peak of average-sized particles with diameters around 1 mm, but as you can see, the particle size distributions are very different ! The Forté generates way less fines (with diameters below 0.5 mm) and slightly less boulders (with diameters of approximately 2 mm), which is indicative of a better quality grinder.
For now, the app is only intended to be used on OS X computers. But if you are running any other kind of system and know your way around Python, you can always download it directly from GitHub and run it with your own installation of Python 3.
I would like to thank Scott Rao for his excitement when I shared this project idea with him, and for beta testing the software. I would also like to thank Alex Levitt, Mitch Hale, Caleb Fischer, Francisco Quijano and Victor Malherbe for beta testing the software.