Physical and functional properties of pulsed-ultraviolet treated starch based films with papaya leaf extract

Abstract

This study developed corn starch (CS) films incorporating aqueous papaya leaf extract (PLE) and examined the effects of pulsed ultraviolet (PUV) treatment at 4, 12, and 15 J cm⁻² on their physical, mechanical, and antioxidant properties. PLE incorporation increased opacity, water contact angle, surface roughness, and antioxidant activity, but reduced solubility, water vapour permeability (WVP), and tensile strength. PUV treatment further decreased thickness, solubility, and WVP, while significantly (p < 0.05) increasing tensile strength and reducing elongation at break, consistent with starch retrogradation and increased crystallinity. Colour, opacity, hydrophilicity, and antioxidant capacity, measured by total phenolic content (TPC) and DPPH scavenging, remained unaffected (p ≥ 0.05) by PUV. CS films containing PLE exhibited 90.45% higher TPC than pure CS films (control). Phenolic migration was greater in water than ethanol, reflecting the films' hydrophilic nature and faster release in aqueous environments. Overall, PUV treatment improved the mechanical durability of CS + PLE films without compromising antioxidant activity, supporting their potential as sustainable active packaging with tailored release for specific food systems.