Ultraviolet

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Sweet Maria's
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Re: Ultraviolet

Postby Sweet Maria's » Mon Mar 14, 2016 9:37 am

Hi all - Yes we continue to use UV light to inspect coffee here, and along with checking Water Activity, it is part of our normal prescreening. The best light we have found for this is an 18" long twin tube fluorescent fixture, but I can't say if it is UV-A or UV-B. I believe some of the LED flashlights sold online specify wavelength but this does not. All I know is it works very well. What is harder to communicate is the standards to benchmark a coffee to. Indonesian coffees that are wet-hulled are particularly difficult since the disruption in drying results in so much fluorescing coffee its hard to read. Wet-processed coffees with little silverskin clinging to the bean is easiest. There we are looking for a couple things: fully white fluorescing beans are bad, but at very low incidence might not effect the cup strongly, like 1-2 per 300 gr. Pulper damage is important when it is throughout the sample. This is usually in the form of pulper nicking, little marks or ovals on the bean meaning the parchment layer was opened up as it when through the pulper. The contact of the fermenting mucilage with the seed is not desirable.(You are trying to ferment the mucilage to make it removable from the parchment - you dont want that acidifying fermented water to be in touch with the coffee in the process. Dry process coffees are very hard to read because all the silverskin attached to the bean glows orange under the light.

Anyway, UV is a tool, and its great for confirming something you find in the cup flavor too ... but its not the ultimate predictor of quality... -T
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sweet maria's coffee, west oakland, california.

User avatar
Sweet Maria's
Site Admin
Site Admin
Posts: 597
Joined: Wed Jan 21, 2009 3:30 pm
Location: oakland, ca
Contact:

Re: Ultraviolet

Postby Sweet Maria's » Mon Mar 14, 2016 9:39 am

PS: As you guys noted, I definitely DO share information about UV with farmers when I travel, and usually have my UV LED 2light with me, although I give so many away to farmers I have actually exhausted my supply!
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sweet maria's coffee, west oakland, california.


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