ECO-FRIENDLY PROCESSES TO OBTAIN GREEN COFFEE PROTEIN EXTRACTS: IMPACT ON THE BIOLOGICAL PROPERTIES

Coffee beans are a rich source of nutrients that contribute to the prevention of oxidative stress–related diseases. In this manner, we aimed to investigate the influence of aqueous (AEP) and enzyme-assisted aqueous extraction processes (EAEP) on different biological properties of coffee extracts (protein and antioxidant-rich fractions). Briefly, the aqueous extraction was performed at 1:10 (w/v) solids-to-liquids ratio (SLR), constant stirring of 120 rpm, at 50 °C, for 60 min, either at pH 7.0 or 9.0. For EAEP, different enzymes namely alkaline protease (AP), neutral protease (NP), cellulase (C), and hemicellulase (H) were used alone or in combination and thus, the slurry pH was determined by the optimal pH of the enzymatic activity. After undergoing centrifugation, the extracts obtained were evaluated regarding total polyphenol content, antioxidant capacity, protein in vitro digestibility, and the inhibitory effects against α-glucosidase, pancreatic lipase, and angiotensin-converting enzyme (ACE). High digestibility was found for all extracts (>97%), regardless the use of enzymes during the extraction process. Moreover, coffee extracts prepared with neutral protease (NP) and at pH 7.0 presented higher phenolic content and antioxidant capacity when compared to samples extracted with alkaline protease (AP) and at pH 9.0. However, only the addition of AP increased polyphenols extraction when compared to the respective control, which was related to protein–phenolic interaction breakdown at alkaline medium. Both the addition of AP and NP increased the ACE inhibitory activity when compared with the respective controls (AEP-pH 7.0 and AEP-pH 9.0), showing the effectiveness of protein hydrolysates at inhibiting ACE. Additionally, the highest ACE inhibition value obtained (85%) was comparable to captopril (92%), a synthetic drug used for the treatment of hypertension. On the other hand, enzymatic treatments decreased lipase inhibitory activity and the coffee extract obtained by aqueous extraction at pH 7.0 (AEP-pH 7.0) presented the highest inhibition value (66%). Finally, low effectiveness was found for α-glucosidase inhibition (≤14%), regardless of the extraction process. The green coffee extracts obtained through AEP and EAEP are an excellent source of natural bioactive compounds that can be explored as potential replacements for synthetic drugs in the treatment of obesity and cardiovascular diseases.