Monday, November 17, 2014

Batch Volume and Bean Density

The density of beans is an important parameter to decide on an appropriate roast profile. From the given volume and weight of a batch of coffee (green or roasted) entered in the Roast Properties dialog (menu Roast >> Properties) Artisan computes the beans density.

But how to determine the volume of a batch of coffee? You can apply the "PVC pipes" trick Willem Boot is talking about in one of his seminars. 

Take a tall container with a known volume as a unit measure. Fill it completely with the beans. Enter the (unit) weight of those beans as well as the volume of the unit container (can be estimated by filling it with water and weighing that water) in Artisan's Volume Calculator (added in v0.9). That calculator is accessible via the "calc" button from the roast properties dialog and works for green ("in" section) and roasted beans ("out" section).

In the example above, the "PVC pipe", our unit volume measure, has an estimated volume of 2338ml (green circle). The weight of water to fill it completely weighs 2338g. Artisan copies the weight of the green beans (1783g) and roasted beans (1514g) from the roast properties dialog to the Volume Calculator. The weight of the green beans that completely fill the "PVC pipe" has been measured as 1658g (upper blue circle) and entered in the Volume Calculator to the "in" section, resulting in an estimated volume of the full green bean batch of 2514.3ml (in red) as calculated by the Volume Calculator. Similar for the roasted beans. The roasted beans filling the unit measure completely weighed 1732g (lower blue circle), resulting in an estimated volume of 2043.7ml (in red).

On leaving the Volume Calculator by pressing OK, the green and roasted beans bulk volume is copied to the corresponding fields of the Roast Properties dialog. As now both weights and volumes are known to Artisan; it computes and displays the estimated bean densities.

A more readable description of this feature can be found in a recent post by Frans.