Effect of Roasting Degree on the Antioxidant Properties of Espresso and Drip Coffee Extracted from Coffea arabica cv. Java

Abstract

Coffee roasting is the process of applying heat to green coffee beans to bring out flavors through chemical changes. This study aimed to investigate the effect of roasting degree on the antioxidant capacities of espresso and drip coffee extracted from Coffea arabica cv. Java in Laos. Green coffee beans were roasted under four conditions (Light-medium, Medium, Moderately dark, and Very dark), and espresso and drip coffee were extracted. The contents of total phenolics (TP), total flavonoids (TF), and chlorogenic acids (CGA) decreased as the roasting degree increased, whereas the caffeine content increased. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was lower in the Medium, Moderately dark, and Very dark compared to the Light-medium. The ferric reducing antioxidant power (FRAP) was lower in the Very dark than the Light-medium, Medium, and Moderately dark. Principal component analysis showed that TP, TF, CGA, caffeine, DPPH radical scavenging activity, and FRAP distinguish coffee extracts with various roasting degrees. Therefore, it is concluded that roasting degree is a modifiable factor for the use of coffee as an antioxidant material in the food industry, and TF, TP, CGA, and caffeine contents, DPPH radical scavenging activity and FRAP are good indicators for determining the antioxidant capacity of coffee.