Supercritical CO₂ Apple Pomace Extract: Chemical Composition, Antioxidant Activity, Cytocompatibility, Antibacterial...

Apple processing generates large amounts of pomace, a by-product rich in bioactive compounds. This study characterized an apple pomace extract (APE) obtained via supercritical CO₂ and evaluated its antioxidant, cytotoxic, pro-inflammatory, antibacterial and antibiofilm properties. Total phenolic (TPC), proanthocyanidin (TPAC) and flavonoid (TFC) contents, together with DPPH, ABTS, FRAP assays, were determined in the starting material, exhausted residue and APE to assess extraction efficiency. Subsequently, the volatile and water-soluble fractions of the extract were analysed using GC-MS and HPLC-MS, respectively. Its safety was evaluated through a cytotoxicity assay on Caco-2/TC-7 cells and TNF-α secretion, while antibacterial and antibiofilm activities were assessed following a modified CLSI protocol and Innovotech guidelines, respectively. APE showed higher TPC, TPAC and TFC than both starting material and residue, together with strong antioxidant activity. Characterization revealed a predominance of pentacyclic triterpenes and glycosylated flavonols, while volatiles were dominated by alcohols and aldehydes. APE was cytocompatible up to 72 mg mL^-1 and did not induce significant TNF-α release. It inhibited planktonic bacterial growth mainly at 90-180 mg mL^-1, whereas biofilm eradication occurred at 45 mg mL^-1. These findings support the use of apple pomace as a sustainable source of bioactive compounds for food applications.