p ‐Coumaric acid in cereals: presence, antioxidant and antimicrobial effects

Summary Coumaric acid is a hydroxy derivative of cinnamic acid and naturally occurs in three isomers (ortho‐, meta‐ and para‐); p ‐coumaric acid is one of the most commonly occurring isomer in nature. p ‐coumaric acid, classified as a phytochemical and nutraceutical, is found in various edible plants, such as carrots, tomatoes and cereals. p ‐coumaric acid (4‐hydroxy‐cinnamic acid) occurs widely in the cell walls of graminaceous plants. It decreases low‐density lipoprotein ( LDL ) peroxidation, shows antioxidant and antimicrobial activities and plays an important role in human health. It is found in the endosperm of kernels at a limited level; however, the amount of p ‐coumaric acid increases significantly in peripheral tissues. In terms of cereal types, it appears that pericarp fractions in barley, wheat, oat and corn are the fractions richest in p ‐coumaric acid. It is both a good antioxidant and a good antimicrobial; therefore, it is natural alternative instead of synthetic additives, nowadays.