About 6 years ago, I was correlating pH buffering capacity with grain color for several "families" of grains - and the color side of things turned into a hot mess. After talking with a few maltsters and sending a number of European grain samples out for testing, some to an independent lab following ASBC protocols and some to a US maltster, this is what I think I learned:
-US maltsters simply measure SRM and report it as Lovibond.
-EBC has several methods for quantifying color based on the color range of a given grain. I wasn't able to find much detail, but I believe the spectrophotometric method is used for lighter grains and at least one comparison method is (was?) used for darker grains - and there's overlap on where they can be used.
-It was hard to find technical people at European maltsters to talk with, but I got a couple nuggets of info. It seems that when they report in degrees Lovibond, they try to get closer to true Lovibond than US maltsters by using equations like Lovibond = 0.375 x EBC + 0.56. Different maltsters used different variations of that equation, but they were all similar.
-All grains that tested under 90 SRM, a ~170 SRM UK crystal malt, and a German dehusked black malt were reasonably close to the equation Tested SRM = COA EBC / 1.97.
-All UK grains that tested above 500 SRM and a Belgian Special B were reasonably close to the equation Tested SRM = 0.375 x COA EBC + 0.56.
I only had 1-3 samples of each grain type tested (13 grain types total), so take my data with a grain of salt, but I think it's useful for highlighting the ambiguity of grain color reporting. If you unearth more info away from this thread, would you be willing to circle back and post a quick summary?
Thanks!
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Joe Walts
Quality Manager and R&D Brewer
Karben4 Brewing
Madison WI
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Original Message:
Sent: 12-21-2022 17:49
From: Karl Ockert
Subject: Malt color measurement
This query is meant especially to all you maltsters out there (but anyone can reply):
I am researching the color measurement used for malt. Degrees Lovibond is a legacy measurement unit developed in the 1880's that used a visual color scale and tintometer. That method was replaced with the advent of spectrophotometry by the standard reference method (SRM) unit many years ago and all US maltsters use the ASBC SRM method to measure color (tintometers are kept in museums, not labs). I am seeing in the brewing textbooks that deg L and SRM measurements are considered interchangeable. This may be true for pale malts under 3 SRM, but as the malt color darkens the two measurements can diverge by over 30%. For instance, using the equation SRM = (deg L – 0.76) x 1.3546, a 40 deg L measurement translates to 53 SRM. However, we still see malt color referenced in deg L on COA's and sales literature. So in the case of a caramel 40L malt what is its color in SRM? Is the Deg L unit irrelevant to malts over 3 SRM?
Cheers,
Karl
Consulting Brewer
Karl Ockert Brewing Services LLC
www.ockertbrewserv.com
Cell: 503-887-1938