The sour flavor experienced with some foods is due to citric acid. It can be found in many fruits and vegetables, especially citrus fruits such as lemons and oranges.

Citric acid is an organic, crystalline acid that exists in a variety of fruits and vegetables. It is colorless and is derived by fermentation of carbohydrates.

Citric acid can be found in beans, broccoli, carrots, potatoes, rhubarb and tomatoes. The acidity in foods can be measured in “pH” levels. The lower the pH level, the more acid is in the food. Tomatoes are high in citric acid and measure between 4.30 and 4.90 in pH level. Broccoli measures between 6.30 and 6.52 in pH level.

Food manufacturers add citric acid to jams, canned fruits and vegetables. Citric acid is also added to soft drinks for the sour taste.

Many environmentally friendly products use citric acid as their cleaning agent. Citric acid can also be used for odor control.

A person usually consumes about 500 mg citric acid per day. This is about the same as 2 ounces of orange juice. Citric acid is absorbed through the digestive tract and eliminated by the kidneys.