Citric Acid 2 oz
Citric Acid can be used in sanitizing solutions to lower the pH, which will make the SO2 level more effective. In addition, it can increase the acidity of wine at a ratio of .1% for each teaspoon per gallon. If you add too much, it will create a very tart flavor.
Citric Acid is also used to clean copper at a rate of 1 teaspoon per gallon.