Optimization of pullulan-based formulations to obtain films that mimic polyethylene properties. Evaluation of the addition of ascorbic acid and candelilla wax

Pullulan is a plant-derived polysaccharide with excellent film-forming ability but limited by brittleness and hydrophilicity. This study developed biodegradable pullulan films with mechanical and optical properties comparable to polyethylene (PE). Using response surface methodology, formulations were optimized to achieve tensile strength (TS) values up to ~30 MPa and elongation at break (EAB) approaching ~27 %, which are similar of low-density PE films (~35 MPa; EAB ~ 30 %). The optimized films remained highly transparent (opacity 0.18–0.91 mm −1 ; ΔE < 1). However, neat pullulan films became tacky under humid conditions. Incorporation of candelilla wax nanodispersions (0.024–0.64 mg CW/cm 2 film) increased the water contact angle from ~52° to 65° and reduced water uptake and adhesiveness, although higher wax levels caused slight yellowing and reduced TS. Addition of ascorbic acid (10 % w /w) endowed the films with strong antioxidant activity (>80 % DPPH inhibition within 24 h) and significantly delayed browning in fresh-cut apple slices, albeit at the expense of higher hydrophilicity. Overall, the results demonstrate that pullulan films can be engineered to reproduce the mechanical behavior of PE while offering added functionalities such as antioxidant activity and moisture resistance through natural additives. Moisture sensitivity, however, remains the main limitation for industrial application, although it can be mitigated with the use of waxes. • Pullulan film formulations were optimized to mimic PE strength and flexibility. • Candelilla wax reduced tackiness and water uptake in films. • Ascorbic acid enhanced antioxidant function and fruit preservation.