Hydrothermal extraction of tannins from pine bark: Optimization, characterization and comparison with commercial antioxidants

Abstract

Hydrothermal treatment of pine bark was optimized using a Box-Behnken design. Quadratic models for all responses showed good fit (R² > 0.95; p < 0.0001). The optimal conditions were 130 °C, 45 min, solid/liquid ratio 1/20 g/mL, yielding: • Extraction yield: 13.54 ± 1.30 g/100 g dry bark • Total phenolics: 30.18 ± 2.11 mg GAE/g dry bark • FRAP: 13.32 ± 2.80 mmol AAE/100 g dry bark • Condensed tannins: 6.79 ± 1.57 mg CE/g dry bark • Stiasny number: 24.03 ± 4.27 % Extracts showed lower antioxidant capacity than BHA and α-tocopherol in FRAP, ABTS, and DPPH assays. Conclusion: Hydrothermal treatment is a sustainable method to obtain phenolic-rich extracts with measurable antioxidant capacity and promising adhesive properties, supporting their potential application in bioadhesive formulations.