Assessment of Physical, Chemical, and Bioactive Properties of Some Neglected Varieties of Yemeni Coffea arabica L. Green Beans

Coffea arabica L. is an economically important crop grown in diverse geographical regions of Yemen. This study aimed to characterize the physical, chemical, and biological properties of Yemeni green coffee bean varieties collected from eight major coffee-producing areas in Hajjah Governorate. Bean physical traits, including length, diameter, bulk density, and weight, were recorded, and methanolic (MeOH) extracts were prepared to determine total phenolic (TPC) and flavonoid (TFC) contents, caffeine level, mineral composition, antiradical capacity (using DPPH and ABTS tests), and enzyme inhibitory effects (against α-amylase and α-glucosidase). The tested varieties displayed notable characteristics. Physical analysis showed that the beans had the following ranges of length (8.2–10.07 mm), diameter (5.4–7.1 mm), density (0.6–0.72 g per cm3), and weight (14.2–16.6 g per 100 beans). Phytochemical analysis revealed varied content of phytochemicals, with different ranges of TPC (50.09–98.07 mg GAE g−1), TFC (1.77–4.55 mg QE g−1), and caffeine (8.4–13.19 mg g−1). Among the macro-elements, potassium was the most abundant, which ranged from 8.0 to 10.7 mg g−1. Biological tests showed strong antiradical effects, with IC50 values ranging from 0.315 to 1.003 mg mL−1 for anti-DPPH activity and from 0.7419 to 1.6366 mg mL−1 for anti-ABTS effect. A stronger anti-enzyme effect was observed against α-glucosidase (0.89–1.93 mmol ACAE g−1) compared to the α-amylase (0.34–0.67 mmol ACAE g−1) inhibition. Overall, the evaluated samples had physical and biochemical profiles that were comparable to and, in some cases superior to, those of well-known local and international coffee varieties.