Background: Coffee is important source of natural antioxidants in the diet, such as phenolic compounds, alkaloids, mainly caffeine, diterpenes (cafestol and kahweol) and Maillard reaction products formed during roasting.
Methods: In aqueous and methanolic extracts of coffee (Coffea arabica L.) roasted using traditional techniques from Brazil (B), Colombia (C), Ethiopia (E), Kenya (K) and coffee roasted using an industrial technique from Brazil (T), the phenolic and caffeine content as well as antioxidant properties were determined.
Results: Comparing the results from water and methanolic extracts it should be noted that the highest amount of phenolics was determined for a methanolic extract of coffee roasted using the industrial technique (650.96 mg GAE/g DW) and a water extract of Kenya coffee (461.63 mg GAE/g DW). Caffeine content was on average two times higher in all methanolic extracts than in water extracts. The radical scavenging activity of aqueous extracts was found to be higher than methanolic extracts. The highest antioxidant scavenging activity was determined for C (EC50 = 1.16 mg DW/ml) and E (EC50 = 1.3 mg DW/ml) water extracts. Compared to water extracts methanolic extracts showed significantly higher reducing power, ability to chelate Fe2+, inhibition of linoleic acid peroxidation and inhibition of lipoxygenase.
Conclusions: This study demonstrated that the methanolic extracts obtained from different types of coffee exhibit potential anti-inflammatory and antioxidant properties. The highest antioxidant activity was shown by traditionally roasted coffees from Colombia and Ethiopia.
Keywords: antioxidant activity; coffee; coffee roasting; phenolic compounds.