Bench Trials - Acid Adjustment

Bench Trials: Precision Acid Adjustment

When dealing with high-pH wines, a bench trial is the only way to balance chemical stability with sensory quality. This guide helps you determine the exact amount of Tartaric Acid needed to reach your target pH without over-acidifying.

1. Prepare the 10% Tartaric Acid Solution

To make your measurements easy to scale, create a "stock solution" where 1ml of solution = 0.1g of acid.

The Mix: Dissolve 10 grams of Tartaric Acid into 100ml of distilled (DI) water.
The Result: Because this is a 10% solution, every 1ml you add to a 100ml wine sample represents a 1g/L addition to your bulk wine.

2. Set Up the Trial

Samples: Line up five clean wine glasses.
Volume: Pour exactly 100ml of your wine into each glass.
Baseline: Leave the first glass (Glass #0) untouched. This is your "control" for pH and taste comparisons.

3. The Incremental Additions

Using a graduated pipette, add the 10% solution to the remaining four glasses in increasing increments. Stir gently after each addition.

4. Measure and Evaluate

Record pH: Use your pH meter to measure each glass. You will see how your specific wine "resists" change based on its buffer capacity.
Sensory Test: Taste each sample against the baseline (Glass #0). Look for the point where the fruit "pops" and the flat, flabby character disappears—but stop before the wine tastes sharp or "metallic."

5. Scaling to Your Batch

Once you select your favorite sample, use this simple calculation for your bulk wine:

Total Grams to Add = ml of Solution added times Total Liters of Wine

Example: If you preferred Glass #3 (1.5ml addition) for a standard 225L (59 gal) barrel: 1.5g/L * 225L = 337.5 grams of Tartaric Acid

Winemaker's Pro-Tips

Be Patient: Acid can take time to integrate. After adding to your barrel or tank, wait 24–48 hours before re-testing the pH.
Buffer Capacity: High-pH wines often "bounce back" after an addition. You may need to run a second trial a week later if the pH drifts upward as tartrates precipitate.
Safety First: Always add acid to the wine, stir thoroughly, and never add more than 2g/L in a single dose without re-tasting.

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