At some point in the harvesting process we need to determine the moisture content of the beans. If they are too "wet" (high in moisture), they will spoil in storage. We often test as we are harvesting, in an effort to determine if we should continue harvesting, or wait for another day.
This blog post shows a post-harvest test. We already ran these Hidatsa Red beans over the fanning mill to remove most of the non-bean debris.
This is a tool that tests the moisture of common grains. There is a setting for corn, wheat, soybeans and more. But there is no setting for Hidatsa Red beans. Since they are close in size to soybeans, we use that setting.
These beans test at 17.1% moisture. Slightly higher than we'd like, but beans that are slightly high in moisture will finish drying out in the storage bin in a matter of a few days.
For beans that are not similar in size and shape to soybeans, we test the moisture level in the oven. We also doublecheck our fancy tester with this low-tech process. We start by weighing out exactly 100 g of beans, and we spread these beans out in a single layer on a cookie sheet. We bake the beans at a low temperature (250-275) and weigh them every hour or so. As the beans dry out, they lose their excess moisture. What used to weigh 100 g will weigh less and less as time goes on. When the beans stop losing moisture weight, we subtract the end weight from the beginning weight. Beans that finish at 86 g were 14% moisture at their wettest point (100 - 86 = 14).
Knowing the moisture content of harvested beans helps us to make decisions about how to store them.