Evaluation of the Antioxidant Activities of Roasted and Unroasted Coffee Extracts

Oxidation is one of the most important spoiling reaction in the oils and fats and might be delayed by the use of antioxidants to some extent. Coffee contains some effective phenolic antioxidants such as chlorogenic acids, caffeic acids ester and quinnic acids. The object of this research is to study the antioxidant activities of coffee extracts. In this research work coffee extracts were obtained by hexane and isopropanol after three hours of extraction period. The extracts yields and total phenolic compounds were determined using Folin ciocalteu method. The hexanolic and isoporopanolic extracts of both roasted and unroasted coffee from two varieties of coffee (Arabica, Robusta) were added to tallow at different concentrations. Peroxide value at 100UC (oven) and Induction period measurements at 110UC (Rancimat) were used as means to examine and investigate the antioxidant activities of the above extracts. The results indicated that coffee extracts inhibited antioxidant activities and were able to reduce the oxidation chain reaction. The highest yield of phenolic compounds, taking Gallic acid as the index was related to the extracts obtained by isopropanol and accounted for 2.17 mg/g of dry matter. This might be due to higher polarity of isopropanol as compared to hexane. Among the extracts isopropanolic extract of roasted Robusta with 15% concentration exhibited the best antioxidant activity.