Green Extraction and Optimization of Bioactive Compounds from Elderberry (Sambucus nigra L.) by β-Cyclodextrin Assisted Extraction Short title: Optimized Green Extraction of Elderberry Bioactives with β-Cyclodextrin

Phenolics of elderberry ( Sambucus nigra L.) were recovered via a green, β-cyclodextrin (β-CD)–assisted aqueous extraction. Process effects were mapped using response surface methodology (face-centered central composite design) with β-CD 1–3% (w/v), liquid–solid (L/S) ratio 10–30% (w/v), and time 30–90 min. Responses (TPC, TFC, TMAC, TPAC; DPPH, FRAP, CUPRAC) were modeled to identify operating windows. TPC followed a quadratic relationship; TFC a reduced quadratic with an optimum near ~ 2% β-CD, whereas TMAC and TPAC exhibited approximately linear trends across the studied space. DPPH showed clearer parameter sensitivity than FRAP/CUPRAC, and extraction time exerted a secondary effect within 30–90 min. Contour plots consistently indicated low-to-moderate L/S together with ~ 2% β-CD as a region that balances multiple responses while avoiding dilution or mass-transfer limitations. Overall, β-CD–assisted extraction provides an effective, solvent-lean route for recovering elderberry phenolics and delineates a practical window for greener processing. These results motivate follow-up work on inclusion mechanisms, stability during storage and digestion, and scale-up supported by techno-economic and life-cycle assessments.