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The Measurement of Titratable Acidity (TA)

Introduction

Advantages/disadvantages of methods/variations below.

The procedure -


• using a pH meter to determine the TA.
  
  
• using a non-diluted sample and colour indicator to determine the TA.
  
  
• using a diluted sample and a colour indicator to determine the TA.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

• Titratable acidity is an approximation for total acidity.
  
  
• The titratable acidity of a solution is measured by reacting the acids present with a base such as sodium hydroxide(NaOH) (see equation) to a chosen end point, as indicated by an pH colour indicator or by a pH meter.
  
  
• This is performed by securing a representative, prepared sample of grape juice or wine and pipetting an accurate quantity (10 ml) of this sample into a 100 ml beaker or conical flask .
  
  
• Added to this accurately measured sample are a few drops of pH indicator solution (phenolphthalein soln.) if not using a pH meter.
  
  
• This solution is then titrated to a persistent pink end point or a pH of 3.85, using a 0.1 M sodium hydroxide (NaOH) solution, delivered by a 25 ml or 50ml burette.
  
  
• The volume of NaOH solution required is recorded and the titratable acidity calculated.