Antioxidative activity of green and roasted coffee beans as influenced by convection and microwave roasting methods and content of certain compounds

Antioxidative activity of green and roasted coffee beans and its correlation with the concentrations of certain substances (polyphenols, caffeine, 5-hydroxymethylfurfural) and the roasting method (convection and microwave) was determined. Antioxidative capacity was estimated based on the capability of synthetic free radical (1,1-diphenyl-2-picryl hydrazyl, DPPH.) scavenging and counteracting an oxidation of the model system composed of beta-carotene and linoleic acid. Green coffee appeared to display the highest effectiveness. In the case of roasted coffee samples, the results of neither test showed distinct correlation; however they indicated that an application of microwave heating for coffee roasting better protected its antioxidative properties. This relationship corresponded to the polyphenol content in roasted beans.