Acid Test Kit
4 oz. Sodium Hydroxide 0.100 N (NaOH)
½ oz. Phenolphthalein Indicator
250 ml Erlenmeyer Flask
Two 10cc Syringes
*ALWAYS WEAR EYE PROTECTION WHEN USING THIS ACID TEST KIT*
- WHEN TESTING WHITE WINES: Fill flask with 2 oz. or 60cc distilled boiling water. To this, add 10cc juice or wine (use one syringe for only the juice) and mix well. OR….
- WHEN TESTING RED WINES: Fill Flask with 4 oz. or 120cc distilled boiling water. To this, add 10cc juice or wine (use one syringe for only the juice) mix well.
- Add 5 drops Phenolphthalein Indicator
- Now use the second syringe and fill it with 10cc of Sodium Hydroxide. Slowly add Sodium Hydroxide to the wine or juice in the flask, swirling the flask continuously until the “end point” is reached. The “end point” is that point at which all the acid has been neutralized. The “end point” for white wines is light pink to orange-pink, and gray-green or brown, for red wine. Record the total cc of Sodium Hydroxide used.
- To determine the amount of acid, take the total cc used to reach the “end point” and multiply by 0.075. Example: if the total cc used was 9, then 0.075 x 9cc = .68%)
- Make sure the bottles are kept sealed when not in use as both solutions will deteriorate by exposure to air. Wash your hands, syringes, eye dropper and flask after use.
To increase acid, use Tartaric Acid or for Fruit Wines, use Acid Blend. 1 oz. acid added to 5 gallons of must raises the acid content by .15%.
To decrease the acid content, the best method is to blend high acid grapes with others known to be low in acid. A much less desirable way to reduce acid would be to add water.
Approximate Desirable Acid Levels:
Red Grape Wine .65% to .75%
White Grape Wine .7% to .8%
Fruit Wines .6%