CZE analysis of coffee extracts possessing antioxidant and antibacterial capacities

Abstract

Coffee beverage has been associated with antibacterial and antioxidant capacities. This investigation aimed at identifying and quantifying natural compounds in coffee that contribute to these properties. Coffee chemical compounds (chlorogenic acid) and aqueous extracts of green regular and decaffeinated Arabica and Robusta coffee beans were tested. Antioxidant properties of the coffee extracts were determined by TEAC and 2-deoxyribose degradation assays. An extract from Vietnam Robusta green coffee beans possessing the highest antioxidant capacity among the samples, was selected and its antibacterial effect against Campylobacter jejuni, which is considered the most common causes of bacterial foodborne diarrheal disease throughout the world, was determined. The minimal inhibitory concentration (MIC) of Vietnam Robusta green coffee against Campylobacter jejuni was performed. Chemical composition of the extracts was established by CZE. Antioxidant and MIC results were correlated with the concentration of one of the major coffee compounds in the extracts. Chlorogenic acid, the most abundant phenol antioxidant naturally present in coffee extracts, showed bacteriostatic activity and antioxidant capacity against either ABTS•+ or hydroxyl radicals. In conclusion, CZE analysis allowed chemically characterize the green coffee extracts and identify chlorogenic acid as a main antioxidant and bacteriostatic compound of the extracts. To the best of our knowledge, this is the first time that is ascribed antibacterial activity against Campylobacter jejuni to coffee compounds and particularly to chlorogenic acid. Other major components of the extracts like trigonelline and caffeine may also exhibit both antibacterial and antioxidant properties and their contribution to the overall properties of the green coffee extracts are being investigated.