The Relationship Between Wort Gravity and Water-to-Grist Ratio (Revisited)

John Palmer. MBAA Publications Director.
The wort gravity from a mash is directly related to the potential soluble extract of the malt and the water-to-grist ratio of the mash. A simple model based on a conversion equation for percent extract (°Plato) to specific gravity from de Clerck is presented. The model was tested with a series of small mashes and the data set supports the model. If the brewer mashes new grist with wort from a previous mash, the new wort will have a gravity that is equal, or nearly equal, to the sum of the gravity of the previous wort and the gravity of the wort predicted by the model for gravity as a function of water-to-grist ratio for the second mash.