Sea buckthorn pomace - enhanced SPI bio-composite films: Microstructure, thermal stability, barrier properties, and their applications in meat preservation

In response to the growing environmental concerns over conventional plastic packaging, this study developed soy protein isolate (SPI) films incorporated with sea buckthorn pomace (SBP), a bioactive-rich agro-industrial byproduct, for use in active meat packaging. Biocomposite films were fabricated via solution casting with SBP concentrations of 0-5% (w/w). Incorporation of 3% SBP led to a significant enhancement in material properties: tensile strength (TS) increased by 45% (to 5.5 ± 0.4 MPa), Young’s modulus (YM) doubled (to 85.7 ± 6.2 MPa), water vapor permeability (WVP) decreased by 30% (to 1.50 ± 0.08 × 10⁻ 1 ⁰ g·m/m 2 ·s·Pa), and oxygen permeability dropped by ∼33% (to 3.9 ± 0.2 × 10⁻ 1 ⁴ cm 3 ·m/m 2 ·s·Pa) compared to control films. DPPH and ABTS assays revealed that antioxidant activity reached 65.8% and 75.2%, respectively, for 5% SBP films. Application to pork loin preservation at 4°C over 15 days demonstrated that SPI-SBP 3% films suppressed lipid oxidation by over 50% (Thiobarbituric acid reactive substances (TBARS) reduced from 1.85 to 0.85 mg MDA/kg) and curtailed microbial growth (Total viable count (TVC) reduced by ∼2 log CFU/g), while also minimizing weight loss. These outcomes confirm the dual role of SBP as a structural and functional enhancer, reinforcing the utility of SPI-SBP films as biodegradable, bioactive alternatives to petroleum-based meat packaging, with added value from agro-industrial waste valorization.