Valorisation of chestnut burr (Castanea sativa) waste by a novel sustainable matrix solid-phase dispersion: Polyphenol profiling and bioactive activities assessment.

Chestnut burrs (Castanea sativa) are abundant agri-food residues with potential as a source of fibre and polyphenols. This work proposes a matrix solid-phase dispersion-ultrasound-assisted extraction (MSPD-UAE) method for the recovery of phenolic compounds from chestnut burr residues. A multi-level factorial design was applied for process optimisation. Chemical characterization by cLC-DAD-ESI-MS revealed ellagic acid (200 ± 20 μg·g-1) and catechin (195 ± 8 μg·g-1) as the major phenolic compounds. Mineral analysis showed high concentrations of calcium and phosphorus, whereas low levels of Cu, Fe and Zn were detected. The phenolic extracts exhibited antioxidant activity (DPPH IC₅₀ = 121 ± 6 mg·L-1; TBARS IC₅₀ = 5.8 ± 0.5 mg·L-1), ACE inhibitory activity (IC₅₀ = 51.9 ± 0.9 mg·L-1), and modulation of Aβ42 aggregation. In addition, the AGREEprep assessment suggested moderate green performance for the proposed extraction methodology.