Even ripe, juicy tomatoes can yield a sauce with an undesirably acidic bite. Easy fixes to this problem take just seconds of your time and either mask the acidic flavor or change the chemical balance of the sauce to make it delicious.
Neutralize the Acid
Baking soda is the first in line of several tools to help neutralize acid. Sprinkle a 1/4 teaspoon across the surface of the sauce, waiting for the baking soda to bubble and react before tasting the sauce. Depending on the amount of acid and size of the batch of tomato sauce, you may need to add more, but start small and work your way up. This method changes the pH of the sauce; use only a small amount at a time. Too much baking soda gives the sauce an undesirable flavor that you cannot reverse.
Mellow It Out
Butter often does the trick to mellow out the acidic tones of a tomato sauce. Stir a generous pat of butter into the sauce. The creaminess of the butter may cover the acidic flavor on its own; you can also combine it with other methods to minimize the acidity of the sauce. Depending on the degree of acidity, butter may or may not provide the necessary change on its own.
Sweeten It Up
You can also mask acidity in tomato sauce with sugar. The amount of sugar you need varies depending on the size of the batch and degree of acidity. Start with a teaspoon and add a bit more incrementally until you achieve the desired taste.
In some cases, the acidic nature of the tomatoes or an extended cooking time that concentrates the acids makes it impossible to salvage a sauce. Avoid cooking tomato sauce for more than 30 minutes to prevent too much liquid from evaporating and concentrating the acids in the sauce in the first place. A combination of tomato types, growing conditions and ripeness can all contribute to an overly acidic sauce; at times, you simply can't get rid of the undesirable flavor and you should toss the sauce.