STUDY OF THE ANTIOXIDANT ACTIVITIES AND THE PHENOLIC COMPOUNDS IN THE GROUNDS OF ARABICA AND ROBUSTA COFFEES

Despite the socio-economic impact of the COVID-19 pandemic, coffee consumption and popularity continue to increase. This progression in coffee consumption is correlated with an increase in the production of by-products such as coffee grounds, which have been increasingly reused in other industries, such as agriculture, and other food and health-related applications, in order to follow better green chemistry practices. The objective of this study is to evaluate the chemical composition of the macerate of two varieties of spent coffee grounds , namely Robusta and Arabica, using two solvents (water and 80% methanol), as well as the evaluation of their antioxidant power. The investigation of the chemical composition of the different extracts was carried out by quantifying the levels of total polyphenols (TPC), total flavonoids (TFC) and condensed tannins (TTC). Furthermore, the evaluation of their antioxidant potential was carried out by referring to several methods such as: total antioxidant capacity (TAC), ferric reducing antioxidant power (FRAP) and DPPH free radical scavenging. The results of the comparative analysis between Robusta and Arabica coffee grounds revealed significant differences in their phenolic profiles. In general, extracts from Robusta coffee grounds show higher values than those from Arabica coffee grounds. Regarding the antioxidant activity, the results show that Robusta coffee grounds have a higher antioxidant activity than Arabica coffee grounds, whether it is the total antioxidant activity (TAC), the FRAP test or the DPPH test. These results suggest the opportunity for increased valorization of coffee grounds as a potentially beneficial resource for health and pave the way for multiple uses, thus providing environmental benefits.