A COMPARATIVE ANALYSIS OF PHENOLIC CONTENT AND ANTIOXIDANT ACTIVITY IN AMAZONIAN ROBUSTA COFFEE BEANS AND HUSKS PROCESSED BY DRY AND WET METHODS

Coffee stands out as one of the primary agricultural commodities. Coffee industry generates significant solid waste, and coffee husks hold economic and sustainable potential. Coffee processing also impacts the physical-chemical composition of the husk and the bean, which influence its quality and applications in industry. The present study aimed to quantify the total phenolic content (Folin-Ciocalteu) and antioxidant activity (ORAC, FRAP and DPPH) of coffee husk and beans processed by dry (natural cherry) and wet processing (despulping cherry). The samples were obtained from Amazonian Robusta coffee fruits (C. canephora L), provided by EMBRAPA-RO. From the husks and beans, aqueous (10% w/v) and ethanolic extracts (ethanol/water 7:3) were prepared, respectively, natural green bean (NBaq and NBet), despulping green bean (DBaq and DBet), natural husk (NHaq and NHet) and despulping husk (DHaq and DHet). In relation to total phenolics, green beans (NBaq: 93.25±1.06 mg/g GAE; NBet: 166.02±2.92 mg/g GAE; DBaq: 99.56±0.62 mg/g GAE; DBet: 180.27±9.30 mg/g GAE) exhibited higher content compared to husks (NHaq: 69.63±2.22 mg/g GAE; NHet: 42.55±2.20 mg/g GAE; DHaq: 45.20±0.34 mg/g GAE; DHet: 8.87±0.48 mg/g GAE), regardless of the extracting solvent or processing method (p<0.001). Regarding the antioxidant analysis, coffee beans also exhibited superior values compared to husks (p<0.05). Standing out among the beans, DBet (ORAC: 803.61±56.37 µM TE/g; FRAP: 62.55±0.86 µM Fe2SO4/g; DPPH: 1722.22±74.56 µMTE/g) exhibits the highest antioxidant activity. Among the husks, NHaq stands out (ORAC: 168.54±18.56 µM TE/g; FRAP: 0.37±0.01 µM Fe2SO4/g; DPPH: 1163.89±161.66 µMTE/g). In conclusion, the use of ethanol optimized the extraction of phenolic compounds in green beans; however, in the husks, water exhibited greater efficiency. In relation to method, our findings suggest that wet processing of beans tends to mitigate the degradation of phenolics. Conversely, wet processing of husks led to reduced antioxidant potential, suggesting loss of phenolic compounds due to fruit washing.