Advancing the production of green coffee extracts: Sustainable extraction methods and their role in enhancing bioactive properties

Green coffee beans are a rich source of valuable compounds, including phenolics (e.g., chlorogenic acid), alkaloids (e.g., trigonelline., theobromine, and caffeine), and diterpenes (e.g., cafestol and kahweol), all of which contribute to their nutraceutical properties. Additionally, despite being overlooked, green coffee presents a significant protein content (~12%d.b.), with the potential to release bioactive peptides, thereby enhancing its bioactivity. While the influence of extraction methods and parameters on the yield of coffee bioactive compounds has been studied, a critical gap remains in understanding how these factors affect different biological activities of the resulting extracts. This study investigated the effects of eco-friendly aqueous (AEP) and enzymatic extraction processes (EAEP) to produce phenolic- and peptide-rich extracts from green coffee flour, aiming at understanding how these processes influence coffee bioactivity. The effects of extraction pH in the AEP (pH7 vs. pH9) and various enzymatic strategies in EAEP (using proteases and carbohydrases) were assessed regarding protein digestibility, antioxidant and antimicrobial activities, and the inhibitory effects of the extracts against α-glucosidase, pancreatic lipase, and angiotensin-converting enzyme (ACE). Coffee extracts exhibited high digestibility ( >98%) regardless of the pH and use of enzymes during extraction. Alkaline pH decreased the amounts of total phenolic compounds and, consequently, antioxidant activity of the extracts, due to the degradation of chlorogenic acid, catechin, epicatechin, cinnamic acid, and caffeine (a xanthine). The highest lipase inhibition (66%) was observed in the AEP extracts (AEP-pH7), while EAEP extracts demonstrated up to 85% ACE inhibition. This strong ACE inhibitory activity was likely related to the presence of both phenolics (primarily chlorogenic acid) and smaller peptides. Oppositely, low α-glucosidase (< 14%) and antimicrobial (< 10¹CFU/mL) inhibition were observed. These findings highlight the potential application of green coffee extracts in the treatment of obesity and heart disease, with their bioactive properties being tailored by the extraction strategy.