Isolation of green coffee chlorogenic acids using activated carbon

Abstract

Chlorogenic acids, which are interesting natural antioxidants widespread in the plant kingdom, were extracted and purified from Mexican green coffee beans (Coffea arabica) using different methods. The final objective was to find an easy way to extract high-value molecules from a complex mixture, avoiding as much as possible the use of toxic solvents. Three extraction methods (hot water at 80°C, aqueous methanol 70% (v/v), and aqueous isopropanol 60% (v/v)) were tested in combination with two isolating methods (activated carbon, different solvents). The extracted amounts of chlorogenic acids with the six treatments (4.67–5.87% dry basis) presented no significant differences. The one using hot water for extraction and of activated carbon for isolation, was the simplest and the most environmentally friendly. Thus it can be used as a previous step to obtain from green coffee a mixture rich in chlorogenic acids which can be further fractionated to purify a specific chlorogenic acid (i.e. in this work, 5-O-caffeoyl quinic acid using a silica gel column). Chlorogenic acids can be used as natural antioxidants in food or non-food products. To the best of our knowledge, activated carbon has not been used to isolate chlorogenic acids from green coffee.