Understanding coffee beans at its raw form. I got this concept from Sweet Maria's, and I want to share to all of you this extra way of assuring quality coffee. In addition to the green coffee grading implemented by SCAA, using ultraviolet light shows another aspect of coffee that is not seen by the naked eyes.
Green coffee under ultraviolet light shows some stories we havent seen before.
Above are two different beans, on the left is a typical green bean and on the right is a monsooned malabar. The monsooned malabar is golden yellow due the process it went through during the monsooned months.
Below is the coffee beans on the left under ultraviolet light
Below is the monsooned malabar coffee bean under ultraviolet light. Notice the difference, malabar has a different reaction to the uv light. This is due to moisture content of the beans.
The pictures below are two different roasted coffee beans and see how they look like under the UV light
So, what is this all about? pictures above specially the green coffee beans, in terms of quality have passed sort of call it quality control. Now, you might ask, what is failed to pass quality control? This is when we talk about luminescense under ultraviolet light. Bad coffee beans, literally glows or has luminescense. This is due to bacterial infection or bad drying as what we have learn from Sweet Maria's, and yes they do affect the taste. You can detect this as the coffee cools down since your mouth sensories are able to accept warm coffee verses hot.
How do they look like? We went to our roasting training beans, these are like throw away beans, its not for tasting but for wasting during roaster experimentation, meaning these beans failed shy from the physical, or should i say visual naked eye quality. And yes we found some luminescent green beans. They glow among the rest of the beans, it was like sort of picking gold from the rocks.
Ultraviolet Light or UV light can further assure quality of the beans. At least we can identify and pick them if ever we do encounter them.