Phenolic acids can be divided into two classes: derivatives of benzoic acid such as gallic acid, and
derivatives of cinnamic acid such as coumaric, caffeic and ferulic acid. Caffeic acid is the most
abundant phenolic acid in many fruits and vegetables, most often esterified with quinic acid as in
chlorogenic acid, which is the major phenolic compound in coffee. Another common phenolic acid is
ferulic acid, which is present in cereals and is esterified to hemicelluloses in the cell wall [1].