On 10/22/03 5:07 PM, in article ,
"danno" > wrote:

> I have finally moved from the Brew King kits to buying grapes. I picked up
> 100 pounds of Cabernet grapes the other day and they are happily fermenting
> away (still on the skins). OG was 21.3°P and TA was between 60 and 70 I
> should have used smaller increments but WTF, it was my first time measuring
> TA). What is the difference between TA and pH? I have a chem degree some a
> technical answer is welcome. I haven't measured pH yet as my meter needs new
> batteries.
>
> -Danno

Since you have a chem degree, you know pH is a measure of the Hydronium ion
concentration in solution (H20 + HX <---> H3O+ + X-). The pH is highly
subject to the buffering action of the other substituents in the wine
(potassium salts, etc). The TA number (titratable acidity) is a measure of
how many acidic protons can be neutralized with NaOH, but it refers to a
standard. Typically, the TA 0.60-0.70 referes to the percent of tartaric
acid (2 equivalents of H+) present in the wine. Some standards use H2SO4 as
the standard the TA is related to. Sometimes you will see TA represented as
percent, and sometimes as g of the specific standard acid per L.