Mini Titrator for Measuring Titratable Acidity

The HI84529U-01 uses methods based on AOAC International and Standard Methods for the Examination of Dairy Products. Both of these methods report titratable acidity as % lactic acid and a conversion factor is used to convert the results to the other available units. The HI84529U-01 can be customized to meet the needs of any dairy analysis lab. Samples can be titrated by weight or volume, diluted or non-diluted (low range only) and titrated to a fixed pH endpoint that can be adjusted by the user. The HI84529U-01 offers three different methods depending on the expected range and the weight of sample used. Select low range 50 to titrate a 50 mL or 50 g undiluted sample. The other titration options are low range 20 and high range 20 to titrate 20 mL or 20 g samples that are diluted twice their volume with deionized or distilled water.

There are two fundamentally different measurements of dairy products: titratable acidity and pH. pH is a measurement of hydrogen ion concentration while titratable acidity is the neutralizing capacity of a dairy product with NaOH. An increase in acidity can be caused by bacteria formation. Monitoring acidity is a way of determining the quality and freshness of dairy products. Acidity is determined by a pH endpoint titration using NaOH (sodium hydroxide) and is defined as the consumption necessary to shift the pH value from 6.6 (corresponding to fresh milk) to a pre-determined pH value. When using phenolphthalein as an indicator, a faint pink color change occurs at pH 8.3.

Titratable acidity is expressed in a variety of units based on the titration method performed. Each method varies in sample size and strength of NaOH used for the titration.

% Lactic Acid (%l.a.): Determined by taking a 20 mL or 20 g sample and diluting with twice its volume with deionized or distilled water. The sample is then titrated with 0.1 M NaOH to a phenolphthalein endpoint.

Degree Soxhlet Henkel (°SH): Determined by titrating a 50 mL sample with 0.1 M NaOH to a phenolphthalein endpoint.

Degree Dornic (°D): Determined by titrating a 100 mL sample with N/9 NaOH to a phenolphthalein endpoint.

Degree Thrner: Determined by taking a 10 mL sample and diluting with twice its volume with deionized or distilled water. The sample is then titrated with 0.1 M NaOH to a phenolphthalein endpoint.

Knowing the relationship between sample weight or volume and strength of titrant it is possible to convert the reading obtained from one method to another. Below is a table with the factors preprogrammed in the HI84529U-01 for converting between various units of measure.

From

To

Divide By

%l.a.