- Oxalic acid is the main acid present in tomatoes. - Tomato contains more than 10 types of acids such as citric acid, malic acid, ascorbic acid, and oxalic acid. - Tomato contains different types of acids, but two accounts for a large percentage of the total citric acid and malic acid. - Tomato also contains another essential acid, ascorbic acid, which is Vitamin C. - Above all three acids have a role in protecting your health and sustaining energy.