Beer’s Law – Dan A. Morey: “It has been well documented that beer color is not a linear scale. So why try to relate Malt Color Units to an estimated SRM by a linear equation? I propose a power equation would better approximate the color phenomenon.
What I did was: Assume MCU = SRM from 0 to 10.5, Daniel’s equation holds in the range of 10.5 < MCU < 37, and Mosher's formula holds for MCU < 37. Then I plotted In (MCU) vs. In (SRM) and performed linear regression. This exercise resulted in a R^2 value of 0.97 (This is better than my linear fit with force zero intercept on the MCU vs. SRM graph – R^2 0.96). My resulting equation is:
SRM = 1.4922 [(MCU) ^ 0.6859] – for values of SRM < 50
Now there is a single equation that can be used to estimate the final color of beer.”