Phenolic acids have recently gained considerable attention because of their numerous practical, biological, and pharmacological benefits. Various polyphenolic compounds are widely distributed in plant sources. Flavonoids and phenolic acids are the two main polyphenolic compounds that many plants contain abundant polyphenols. Chlorogenic acid, one of the most abundant phenolic acids, has various biological activities, but it is chemically unstable and degrades into other compounds or different enzymatic processes.