Citric Acid is found in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit.
It is also the most widely used organic acidulate, probably because it is classified as a weak acid. As with all manufacturing processes, we recommend lab scale trials in order to determine appropriate quantities. Normally the product is titrated with a dilute solution of Citric Acid (10 or 20% in water) until the desired pH is achieved.
Citric Acid is an Alpha-Hydroxy Acid and hence will have some exfoliant properties, although these are much weaker than Glycolic, Lactic and Malic Acids.
It is a natural preservative because of its 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 acts as an antioxidant.