The total alkalinity (TA) was estimated by acid titration using the volumetric method with a phenolphthalein endpoint and methyl orange as an indicator, with sulfuric acid (H2SO4) used as the
titrant (NOM-AA-36-1980).
sample size by reducing the alcoholic KOH
titrant concentration from 0.1 Normal to 0.01 Normal.
Briefly, a solution of 0.1 M HBr in glacial acetic acid was used as a
titrant, 1 wt% crystal violet in glacial acetic acid was used as indicator, and toluene as solvent for the sample.
The concentration of tartaric acid was determined in a solution of 5 g of the juice diluted in 50 mL of distilled water, titrated with a Titrino 848 Plus automatic titrator (Metrohm, Sao Paulo, Brazil) using 0.1N NaOH as
titrant; data were expressed as percentage (%) of tartaric acid (AOAC, 2012).
For each analysis performed with the titrator, specific solutions were prepared and the standardizations of the
titrant solutions of each method were also carried out.
It drives a plastic syringe that is attached to a base platform and, in precise steps, raises the platform, pumping a
titrant into a reaction beaker.
The optimal detection system is 2,2-dimethoxypropane as
titrant, cyclohexane, and isopropanol as titration solvents and methanesulfonic acid as catalyst.