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# How to Calculate Volatile Acidity in Wine

Acidity levels in wine affect different components such as freshness, brightness and tartness. All wine contains many different types of acids including tartaric acid, malic acid, citric acid and acetic acid. Most of the acids found in wine are fixed acids, meaning that they remain in the wine when it is boiled. Volatile acids, on the other hand, evaporate out when the wine in boiled. Volatile acids are a natural product of the fermentation process. If the fermentation process is done properly, the volatile acids should be approximately .03 percent to .06 percent. Calculating the volatile acid will help you determine if your wine has been properly fermented.
1. Obtain a wine sample. Take a 15 cubic centimeter, or 15 milliliter, sample from the wine using the syringe and place it in a glass beaker or container.
2. Add three drops of the phenolphthalein indicating solution to the wine. Use the dropper that comes with the indicating solution.
3. Draw up 10 cubic centimeters of the sodium hydroxide solution into a clean syringe.
4. Add the sodium hydroxide to the wine and indicator solution, one-half a cubic centimeter at a time. After each addition of the sodium hydroxide swirl the solution to make sure that it is completely incorporated. The color may change temporarily and may change back. For white wines, the color will change to pink and for red wines the color will turn greyish. Continue adding sodium hydroxide until the wine solution permanently changes color.
5. Calculate the acidity. Every 1 cubic centimeter of sodium hydroxide added equals .10 percent of acid in the solution. For example if you added 6 cubic centimeters of sodium hydroxide, the solution's total acidic percentage would be .60 percent.
6. Calculate the amount of volatile acid out of the total acidity. Boil a sample of the wine on the stove in a clean pan. Take a 15 milliliter sample of the wine and place it in a clean glass beaker. Repeat steps 2 through 5.
7. Calculate the new total acidity percentage of the boiled wine. Subtract the boiled wine acidity percentage from the total acidity percentage. This gives you the percentage of volatile acidity in the wine. For example, if the total acidity was .60 percent and the boiled acidity was .55 percent, the volatile acidity percentage would be .05 percent.