Valorization of the Bioactive Potential of Juniperus communis L. Berry Extracts Using a Box–Behnken Design and Characterization of Kernel Oil Compounds

This study presents a comprehensive valorization of Juniperus communis L., a plant known for its culinary and therapeutic applications. Juniper berries are rich in antioxidant compounds such as polyphenols and ascorbic acid, while their kernels contain volatile terpenes with notable pharmaceutical properties. We optimized extraction parameters through stirring extraction (1:20 g/mL solid-to-solvent ratio, 55% v/v aqueous ethanol, 80 °C, 30 min) and response surface methodology via a Box–Behnken design. The optimal conditions—55% v/v aqueous ethanol at 80 °C for 30 min—yielded a high polyphenol content of 55.11 ± 1.54 mg GAE/g of defatted dry weight. Antioxidant capacity was confirmed through ferric-reducing and radical-scavenging assays, and 11 individual polyphenols (totaling 5.41 ± 0.27 mg/g) were quantified using a validated HPLC-DAD method. Additionally, this study identified several bioactive compounds in juniper berry raw kernel oil, which exhibited a high oleic acid content (58.75 ± 2.76%)—a nutritionally valuable fatty acid contributing to the oil’s strong radical-scavenging activity (399.83 ± 34.18 µmol Trolox equivalents/kg oil). GC–MS analysis revealed 58 volatile compounds, underscoring the terpene-rich profile of the oil and its influence on antioxidant potential and aroma. These findings underscore the dual valorization of juniper berry fruit and kernel for both medicinal and food industries. The aromatic kernel oil and polyphenol-rich extracts offer natural alternatives to synthetic antioxidants, with added benefits of flavor enhancement and promotion of health.