Biopolymer-based active packaging with TiO₂ and nano-encapsulated essential oils improves postharvest stability of fresh-cut kale.

Fresh-cut kale (Brassica oleracea) is highly perishable due to dehydration, enzymatic browning, membrane damage, and microbial spoilage. This study developed an active packaging system using chitosan-based nanocomposite films containing titanium dioxide (TiO₂) nanoparticles and nanoencapsulated essential oils (EO-NCs) from Thymus daenensis Celak and Bunium persicum. The nanomaterials were synthesized, characterized (SEM, DLS, FTIR, XRD, UV-Vis), and incorporated into absorbent pads for kale storage at 4 °C over 40 days. The packaging significantly reduced weight loss (∼45-55 %), improved chlorophyll retention (∼30-35 %), and preserved membrane integrity (>40 % at day 40). It also maintained phenolics (3.2-3.4 mg GAE/g vs. ∼2.0 in controls), ascorbic acid, and protein (∼25-30 % higher). EO-NCs showed strong antioxidant activity, inhibiting PPO and POD to reduce browning. Mineral retention was enhanced (Mn and Fe ∼20-25 % higher), while microbial growth was suppressed. Overall, TiO₂ and EO-NCs synergistically improved postharvest stability, demonstrating a sustainable strategy for extending shelf life of fresh-cut vegetables.