Which acid is the main acid naturally found in lemons and limes?

Which acid is the main acid naturally found in lemons and limes? Citric acid.

Citric acid is the characteristic organic acid concentrated in lemons and limes. It contributes much of their sharp, tart taste and is present in their juice at substantially higher levels than in many other fruits. Because it is a weak acid, its molecules are only partly dissociated in solution, even though lemon and lime juice taste strongly sour.

The acid is also a normal intermediate in cellular metabolism. In aerobic organisms, it appears at the beginning of the citric acid cycle, also called the Krebs cycle, which helps cells extract energy from nutrients. This biological role is why citric acid is found broadly in living systems, not only in citrus fruit.

Chemist Carl Wilhelm Scheele first isolated citric acid from lemon juice in 1784. Today, commercial citric acid is generally produced by fermentation, especially with the mold Aspergillus niger. It is widely used as a flavoring, preservative, acidity regulator, and ingredient in cleaning products. Acetic acid belongs to vinegar, while lactic acid is associated with sour milk and fermentation.