Determination of the acid content white wine?

There are several methods to determine the acid content in white wine. Here are two commonly used methods:

1. Titration Method:

Materials and Equipment:

- Wine sample

- Buret

- Pipette

- Erlenmeyer flask

- Phenolphthalein indicator

- 0.1 N Sodium Hydroxide (NaOH) solution

Procedure:

- Pipette a 10 mL sample of white wine into an Erlenmeyer flask.

- Add a few drops of phenolphthalein indicator to the wine sample.

- Fill the buret with 0.1 N NaOH solution.

- Slowly add the NaOH solution to the wine sample while swirling the flask.

- Continue adding NaOH solution until the color of the sample changes from colorless to a permanent light pink color.

- Record the volume of NaOH solution used.

Calculation:

The acidity of the wine can be calculated using the following formula:

Acidity (g/L as tartaric acid) = (Volume of NaOH used in mL x Normality of NaOH x Equivalent weight of tartaric acid) / Volume of wine sample in mL

The equivalent weight of tartaric acid is 75 g/mol.

2. pH Meter Method:

Materials and Equipment:

- Wine sample

- pH meter

- Buffer solutions for calibration

Procedure:

- Calibrate the pH meter using the appropriate buffer solutions according to the manufacturer's instructions.

- Dip the pH probe into the wine sample and allow the reading to stabilize.

- Record the pH value.

Calculation:

The acidity of the wine can be estimated from the pH value using a conversion table or mathematical equations. One common equation is:

Acidity (g/L as tartaric acid) = (1.53 x 10^9)/(1 + 10^(pH - 3.48))

The resulting value is an approximate estimation of the total acidity expressed as grams of tartaric acid per liter.

It's essential to carefully follow the specific instructions provided in the chosen method to ensure accurate and reliable results.