Beer color, alkalinity and mash pH
This article uses results from mash pH experiments to shed light on the relationship between beer color, mash pH and water composition. It also develops a formula that can be used to make a crude prediction of the mash pH or the alkalinity necessary for a given mash pH based on the color and mash thickness of the beer. This formula has been implemented in the water calculator (Kaiser_water_calculator.xls) to predict the mash pH from beer color, mash thickness and water composition.
Malt color, type and acidity
Brewers know that darker malts are more acidic. But what does it mean for a malt to be more acidic? They for sure don't taste sour.
Malt acidity is the ability to lower the mash pH and it can be measured via 2 means. One is the pH of a distilled water mash. Because of the absence of pH affecting ions the pH of that mash is determined only by the malt acidity and the mash thickness. Another approach is to take a sample from such a mash and add a strong base (e.g sodium hydroxide) to it until a predetermined pH (e.g pH 5.7) is reached. The amount of base added per unit of malt is a direct measure of that malts acidity. Testing the distilled water mash pH works well for base malts. Specialty malts, however, are generally much more acidic than base malts and testing their acidity through titration works better.
In aforementioned mash pH experiments the following formula was developed for calculating the distilled water pH of a given grist.
Random recipe creation and pH and color calculations
Along with the measured values for the distilled water pH of select base malts and acidity select select specialty malts 210 recipes were simulated. The recipes were thrown together randomly with the following constraints:
Crystal and roasted malts were treated as distinct groups since they also formed distinct clusters when their acidity was plotted over their color.
For all these random recipes the distilled water mash pH of the grist and the color of the beer was calculated. The DI water mash pH was determined for 4 different mash thicknesses 2, 3, 4, and 5 l/kg. For the color calculation it was assumed that the total grist weighed 10 pound and the cast out volume was 5 gallon.