Tomatoes are commonly used in many dishes during cooking, whether you are creating a sauce, chopping them fresh for a salad, or grilling them with meat. One of the downfalls of using tomatoes is that they can be very acidic. There are some ways to curb the acidity in tomatoes during cooking and actual lower the level of it rather than masking it with sugar, such as using overripe tomatoes and ingredients to balance out the acidity levels.
Use fresh tomatoes that are fully ripe or overripe. The more ripe, the lower the acidity level in tomatoes. Also avoid using canned tomatoes, because they often have much higher acidity than fresh tomatoes.
Use ingredients when cooking with tomatoes that are low-acidity or mildly alkaline, such as egg whites, red meat, corn, carrots and green peas.
Stir in a small amount, like a teaspoon, of baking soda into the tomato dish right before it is done cooking. The sodium bicarbonate in the soda helps reduce acid in the tomatoes by neutralizing them. Taste when the baking soda is mixed in to test the acidity, and add a small amount more if desired. Since the soda can drastically alter the flavor of the tomatoes, it is important to test out small amounts at a time.
Grate some cheese over the completed dish, or add a small amount of milk or cream to the dish and stir in. This is ideal for creamy dishes with tomatoes, like soup or pasta. Dairy products help neutralize the acidity in tomatoes.