Predicting Beer Color from Recipes

This article originally appeared in the May/June 2022 issue of Zymurgy Magazine

By Thomas Kraus-Weyermann & Horst Dornbusch

This is the second article in a three-part series about the challenges of specifying beer color at the recipe design stage, as well as measuring it after the beer has been brewed. It examines the most common equations currently in use by brewers around the world for specifying beer color before the brewing process begins.

While measuring color in the finished beer is already a tricky business and thus only and imperfect science (see part 1 of this article series), predicting it at the beer design stage is fraught with even more uncertainty. Internationally, there are now several competing equations in use for this purpose, but, unfortunately, each of them produces a different beer color value if applied to the same grain bill (see Table 1). Likewise, on occasion, these formulae also produce identical predictive beer color values for finished beers of different colors.

The photo shown in Figure 1 illustrates this latter point. It was taken by the authors during an unrelated project. At the recipe design stage, one of the color formulae explained below predicted that the colors of these two Maibocks, mashed with different grain bed compositions, would be mathematically similar, in the range of roughly 22-23 EBC (11-12 SRM; the EBC and SRM units for measuring the color of liquids are explained in part 1 of this article series). In reality, however, as can be seen even with the naked eye, these two beers are of very different colors. When analyzed in the laboratory, the color value of the beer on the left was almost twice of that of the beer on the right. In fact, it was this accidentally taken photo that was the starting point for the research presented here.

Access the full article in the May/June 2022 Zymurgy magazine.

This article includes the following:

• Sources for beer color calculations
• Malt color as a starting point
• The malt color unit of the wort
• Colors of 20 beers calculated by 5 beer color formulae
• Formulae for beer color predictions
• Average percent deviation by formula from spectrophotometer values
• Evaluation of the different formulae