Changes

='''Titratable Acidity=''' (abbreviated as ''TA'') is an approximation of the ''Total Acidity'' of a solution, and is often used in the production of wine. It is expressed in units of grams per liter (g/L). ''Titratable Acidity'' is often mistakenly confused with ''Total Acidity'', but they are not the same thing (see reference). While ''Total Acidity'' is a more accurate measurement of the total acid content of a solution, ''Titratable Acidity'' is usually used because it is easier to measure <ref>[http://wineserver.ucdavis.edu/pdf/attachment/220%20relationship%20between%20total%20acidity,%20TA,%20and%20pH%20.pdf The relationship between total acidity, titratable acidity and pH in wine. Roger Boulton. American Journa l of Enology and Viticulture. 31(1): 76-80. 1980.]</ref>. ''TA'' has also proved to be a useful way to measure acidity in sour beer <ref>[http://blog.ocbeerblog.com/2015/04/13/how-sour-is-your-sour-beer/ How Sour is Your Sour Beer?. OCBeerBlog on Firestone Walker's demonstration of the uses of TA measurements. April 13, 2015.]</ref>.

==TA versus pH==Many sour beer producers use pH to help determine how "sour" their beer is in relation to a set goal, previous batches, or commercial examples.  ==pH== However, often times TA is a more useful measurement of how acidic a beer will be perceived on the palate.

The pH scale is traceable to a set of standard solutions whose pH is established by international agreement<ref name="bates">Bates, Roger G. Determination of pH: theory and practice. Wiley, 1973.</ref>.[1] Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. Measurement of pH for aqueous solutions can be done with a glass electrode and a pH meter, or using indicators.

pH measurements are important in medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment & water purification, and many other applications. <refname="bates">Bates, Roger G. Determination of pH: theory and practice. Wiley, 1973.</ref>.

===Why TA?===When attempting to use pH for sensory parameters (how sour something tastes), the measurement falls short. Humans perceive acidity from tasting acids, not H+ ions. In a strong acid, the amount of acid is always proportional to the amount of H+ ions. However, lactic acid, the primary acid in sour beer, is a weak acid. For various reasons a weak acid does not completely ionize/dissociate.

When attempting to use pH for sensory parameters - how sour something tastes - the measurement falls short. Humans perceive acidity from tasting acidsAny acid not dissociated (in other words, not an acid still holding onto its H+ ions) does not affect pH. In a strong acidOn the other hand, humans will perceive an increased "sourness" based upon the amount of acid is always proportional in a beer, dissociated or not. The best way to the amount test for total acidity, regardless of H+ ions. Howeverdissociation, lactic acid - the primary acid in sour beer, is using a weak acid. For various reasons a weak acid does not completely ionize / dissociatetest called ''Titratable Acidity''.

Any acid not dissociated (in other words, an acid still holding onto its H+) does not affect pH. On the other hand, humans will perceive an increased in "sourness" based upon the amount of acid in a beer - dissociated or not. The best way to test for total acidity, regardless of dissociation, is using a test called "Titratable Acidity" (sometimes also called Total Acidity, which is not entirely an accurate name).  Kara Taylor at White Labs has done a reasonable amount of professional sensory panels showing the correlation between ''TA '' and perceived sour taste, as well as showing no correlation between pH and sour taste. Her full presentation, where most of this information was sourced, is available to any attendee of the 2015 Craft Brewer's Conference.

 # Calibrate the pH meter.# Pipette 50mL of decarbonated beer into the beaker.# Place the pH probe and the ATC thermometer into the beaker, submerge tip in of the probe into the beer.# Fill the buret with 0.1N of NaOH.# Open stopcock the Stopcock and add the NaOH to the beer until pH meter reaches a reading of pH 7.0.# Upon reaching 7.0pH, go slowly add more NaOH until pH meter reads exactly pH 8.2, keeping track of how much NaOH is added.# Record the total amount of NaOH used to reach pH 8.2.# Use the following formula to find the ''Titratable Acidity'': =='''Titratable Acidity = (mL 0.1N NaOH * 0.9) / (mL beer * S.G.)=='''# The number you get is TA in grams/L. 

It may be best to compare the ratio of Titratable Acidity / Final Gravity as sweetness counter-acts acidity in sensory experiments.<ref>Kara Taylor, White Labs - CBC 2015 Presentation "Sour Beer is More than pH"</ref> More information on this procedure is available from the American Society of Brewing Chemists, who publish a similar set of procedures under the name "Total Acidity with Potentiometer".  Jim Crook of Firestone Walker has created a presentation about blending sour beers using TA. Contact him for a copy.  ==References:==<references></references>