Citric acid is a weak organic acid found in citrus fruits.
It is a natural preservative and is also used to add an acidic
(sour) taste to foods and soft drinks.
In biochemistry, it is important as an intermediate in the citric
acid cycle and therefore occurs in the metabolism of almost all
living things.
It also serves as an environmentally benign cleaning agent and acts
as an antioxidant.
Citric acid exists in a variety of fruits and vegetables, but it is
most concentrated in lemons and limes, where it can comprise as
much as 8 percent of the dry weight of the fruit.
