Basic Test for Titratable Acidity (TA)

The Titratable Acidity (TA) test is used to determine the total acidity in wine, specifically tartaric acid, which is responsible for the sour or tart taste in the wine. It is an essential factor in wine quality.

Specification:

• Phenolphthalein Indicator: 1%
• Sodium Hydroxide: 0.10M
• Filter Paper: No.1, 150mm, 50 circles
• Beaker: Squat, Grad. Pyrex – 250ml
• Erlenmeyer Flask: Grad. Pyrex – 250ml
• 50ml Syringes
• Activated Charcoal: 40g
• Stirring Rod: Glass, 30cm x 7mm

Uses and Application:

This test is widely used in the wine-making industry to monitor and adjust the acidity levels in both red and white wines. A precise TA reading allows winemakers to maintain the proper balance of flavor and preserve the wine’s freshness over time. It can also be applied to other beverages where acidity plays a crucial role.

Storage:

• Store sodium hydroxide in a cool, dry, and well-ventilated area, away from acids and water.
• Phenolphthalein Indicator should be kept sealed in a cool place away from direct sunlight.
• Filter paper and other tools should be stored in a clean, dry environment to prevent contamination.

Hazardous:

• Sodium Hydroxide: Highly corrosive, can cause burns upon contact with skin or eyes.
• Phenolphthalein: May be harmful if swallowed or inhaled in large amounts.

Safety Measures:

• Always wear safety gloves and eye protection when handling sodium hydroxide and phenolphthalein.
• Ensure proper ventilation in the working area to avoid inhalation of fumes.
• If contact occurs with skin or eyes, wash immediately with plenty of water and seek medical advice if necessary.

Method – Red Wine:

1. Pour 50ml of red wine into a 250ml glass beaker. Add 1 teaspoon of activated carbon. Mix thoroughly. Leave to stand for 5-10 minutes.
2. Fold a No.1 filter paper (150mm) into quarters and place it 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 color 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 0.10M Sodium 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 color of the solution in the beaker changes from a clear color to a faint, persistent, purple color, then stop adding the 0.10M Sodium Hydroxide from the 50ml syringe.
9. Note the final volume of 0.10M Sodium Hydroxide (0.10M NaOH) remaining in the 50ml syringe. Subtract the final volume of 0.10M NaOH from the initial volume of 0.10M NaOH in the syringe.
10. The Titratable Acidity is calculated as follows:
    Titratable Acidity (TA) = [Initial volume – Final volume of 0.10M NaOH] x 0.75 = grams/liter 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/L of Tartaric acid

Method – White Wine:

Proceed from Step No. 4.