Mrs Wages Citric Acid
Home canning tomatoes from your garden or the store? Follow the USDA's recommendations and add 1/2 teaspoon of citric acid to every quart of tomatoes (half for pints). Most tomatoes are high-acid already, but some varieties need the extra acidity and lower pH that citric acid provides to reduce the risk of potential botulism. Not only does this lower the risk of botulism, but citric acid also keeps your tomatoes from discoloring, for a beautiful vivid red-orange.
Ingredients: Citric Acid, Less than 2% Silicon Dioxide (Anticaking).