BASIC TEST FOR TITRATABLE ACIDITY (TA)
50ml Syringes x 2
Beaker, Squat, Grad. Pyrex – 250ml x 2
Phenolphthalein Indicator, 1% – 50ml
Sodium Hydroxide 0.10M – 500ml
Charcoal, activated – 40g
Filter Paper, Economy, No.1 – 150mm 50 circles
Filter Funnel, Plastic – 100mm
Stirring Rod, Glass: 30cm x 7mm
Erlenmeyer Flask, Grad.Pyrex – 250ml
Method – Red Wine
1. Pour 50ml of red wine into a 250ml glass beaker.
Add 1 teaspoon of activated carbon.
Leave to stand for 5-10 minutes.
2. Fold a No.1 filter paper (150mm) into quarters and place in a 100mm filter funnel located in a 250ml erlenmeyer flask. Pour the carbon/red wine mixture into the filter funnel containing the filter paper.
3. The filtered wine should be clear. If a red or pink colour still occurs then add the filtered wine back into the filter funnel until the filtered wine is clear. 4. Use a 50ml syringe to add 10ml of the clear filtered wine to a 250ml glass beaker. Add also 30ml distilled water (or clean, clear water)
5. Add 3 drops of Phenolphthalein Indicator to the 250ml beaker.
6. Now pour approx. 100ml of 0.10M Sodium Hydroxide into another 250ml beaker. Use another 50ml syringe to draw-up 50ml of the 0.10M Sodium Hydroxide solution to the 50ml mark on the syringe.
Note the initial volume of 0.10MSodium Hydroxide(0.10M NaOH) in the 50ml syringe.
7. Place a glass stirring rod (30cm x 7mm) in the 250ml beaker and gently stir as the 0.10M Sodium Hydroxide solution is slowly added from the syringe to the 10ml of filtered wine in the beaker.
8. When the colour of the solution in the beaker changes from a clear colour to a faint, persistent, purple colour then stop adding the 0.10M Sodium
Hydroxide from the 50ml syringe.
Note the final volume of 0.10M Sodium Hydroxide (0.10M NaOH) remaining in the 50ml syringe
Subtract Final volume 0.10M NaOH from the initial volume of 0.10M NaOH in the syringe.
9. The Titratable Acidity is calculated as follows:
Titratable Acidity (TA) = [Initial volume – Final volume of 0.10M NaOH ] x 0.75 = grams /litre of tartaric acid present in the wine
Example: The Final volume of 0.10M NaOH in the 50ml syringe = 42ml
The Initial volume of 0.10M NaOH in the 50ml syringe = 50ml
Titratable Acidity(TA) = 50ml – 42ml = 8ml x 0.75 = 6g/Litre of Tartaric acid