Presenter: A. J. deLange, Mad Fox Brewing Company, Falls
Church, VA
Clearly it would be advantageous if brewers could enter
parameters describing their malts and water, the amounts of
each, and the amounts of any salt, acid, or base additions into
a spreadsheet or “app” and have it return a reliable mash pH
prediction. This represents the holy grail for home brewers
but would clearly be of value to craft and larger commercial
brewers as well. In this presentation we offer a proton deficit/
surfeit model in which the predicted pH is the pH at which
the total of individual mash component proton deficits equals
the total proton surfeit. We explore methods for determining
(modeling) the proton surfeit/deficit for each relevant mash
component. Among these are a Henderson-Hasselbalch–based
model for carbonate and phosphate and, for malts, a simple
(three term) Taylor series representation of their titration
curves about the distilled water mash pH. Some experimental
data are given. While the models for many of the mash
components may be sufficiently robust, this is not true for all
of them. For example, calcium carbonate and lime additions
do not deliver the alkalinity that stoichiometry predicts. A
theoretical explanation as to why this may be so is presented.
Larger difficulties may lie in obtaining data that accurately
reflect the actual acidity or alkalinity of malts encountered
in the brewhouse on a particular day. These are discussed,
with emphasis on the laborious and time-consuming nature
of properly done malt titrations. Variations between lab and
brewhouse handling, between malt batches, and the fact that
thermodynamic equilibrium is never reached in the mash tun
are noted. We conclude that while accurate mash pH prediction
may be feasible it may, depending on required accuracy, not be
practical.
A. J. deLange is a retired electrical engineer with more than
40 years of experience in signal processing, RF engineering,
estimation, and analysis. He is also a home brewer with more
than 25 years of experience who has particularly enjoyed
applying the disciplines of his professional life to his hobby.
He has a keen interest in brewing water chemistry and beer
color analysis and has published and lectured on those subjects
in the United States and abroad. He is a member of MBAA
and ASBC. He has undergraduate and graduate degrees
in electrical engineering from Cornell University and was
employed by Zeta Associates in Fairfax, VA. He consults for
Mad Fox Brewing Company in Falls Church, VA.
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