After our first conversion, we repeated and replaced our measurements with the use of a US Standard size 20 mesh sieve such that 70-75% of the particles would pass through (according to SCA cupping protocols).
The new conversion scale has been updated as of 12/15/2020 throughout the website, and for historical purposes, the original conversion will remain here.
Comparing the first conversion to the updated conversion, one can observe a shift in measurements as a result of using a different grind size for the first set of measurements compared to the second:
We will continue to add data to our conversion, and will release updates over time as needed. Thanks!
Please find our first conversion from Roast Vision to Agtron Gourmet here!
Protocol:
Sample roasting was carried out on 11/27/2020 using an Aillio Bullet R1 V1. Each batch was 100g, for a total of 9 batches, indicated with red hashmarks on the following image indicating the drop times for each of the batches. The temperatures are NOT accurate, as 100g is too small of a batch size for this roaster’s probe position. While the temperatures are not meaningful, the profile of each roast was reproduced with minimal variation, and each batch was simply stopped at a different development time to simulate different roast levels. Images of each roast follow the profile below.
The roasts are generally even, with some variation due to the challenge of roasting an extremely small sample in a 1kg capacity roaster evenly without scorching or causing other roast defects.
After roasting, the samples were cooled to room temperature, and then placed in jars, loosely sealed for 6 hours. The beans were then measured in a Lighttells CM100+, a Roast Vision, and a third experimental sensor. The grind size for the Roast Vision and experimental sensor were set for Turkish (extremely fine), and the grind size for the CM100+ was medium, to medium fine. Future tests will include the use of coffee sieves to accurately communicate grind size for testing purposes.
Results:
After measuring each of the sample roasts, as well as many other coffees that were currently on hand, the following data was plotted, a linear best fit line was applied, and an equation was extracted to create our first Agtron Gourmet conversion. We will continue to revise the conversion as we gather more data, ensuring grind size is accurate, and accounting for any other variation.
By popular request we’ve released a Google Form and accompanying Spreadsheet where users can enter their Roast Vision measurements of their favorite coffees, and view the public results!
