EFFECT OF GERMINATION TIME ON THE CHANGES OF BIOACTIVE COMPOUNDS AND ANTIOXIDANT ACTIVITIES OF ROBUSTA COFFEE BEANS

Abstract

Fresh coffee beans are known as a rich source of bioactive compounds. However, these valuable substances decrease after roasting. Numerous studies show that the germination process improves the composition of the health-beneficial components. In the current study, Robusta coffee beans were used to investigate the change in polyphenols, flavonoids and their antioxidant activities during germination. The results showed that these two components significantly changed over a germination period, reaching their highest values of 40 ± 1.19 mg GAE/g and 19.38 ± 0.16 mg CE/g after 11 days of germination, followed by a gradual decrease (p < 0.05). The antioxidant activity of the germinated coffee bean extract was evaluated using two antioxidant assays, namely the ABTS radical scavenging capacity and the ferric reducing antioxidant power (FRAP). Both parameters varied in parallel with the changes in total polyphenol and flavonoid contents. The ABTS radical scavenging capacity increased by 1.22 folds, reaching 29.13 ± 0.26 mg VCE/g, and the FRAP assay values increased by 2.22 folds, reaching 18.03 ± 0.44 mg VCE/g compared to the control. These research findings indicated positive changes in bioactive compounds occurred in Robusta coffee beans during germination under optimal germination conditions. This study serves as an initial foundation for further research and the development of health-promoting functional foods derived from germinated Robusta coffee beans.