Edible nanogel coatings based on PVP/gelatin/curcumin system for strawberries preservation in challenging storage environments

This study aimed to develop and evaluate a gamma-radiation synthesized, flower-like nanogel composed of polyvinylpyrrolidone (PVP), gelatin (G), and curcumin (Cur), referred to as (PVP/G)/Cur, as an innovative edible coating system to extend the shelf life of strawberries stored under non-ideal conditions (27–40 °C, non-ventilated environment). Addressing the challenge of rapid spoilage due to microbial contamination and oxidative degradation within 2–3 days in such environments, the study introduces a novel gamma irradiation (5 kGy) synthesis method to fabricate nanogels with a hydrophobic curcumin core and a hydrophilic PVP-gelatin shell, enabling controlled release and enhanced barrier properties. The nanogels were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet–visible (UV–Vis) spectroscopy, and scanning electron microscopy (SEM), as well as antimicrobial disc diffusion and antifungal assays against Botrytis cinerea. The resulting nanogels exhibited a mean hydrodynamic diameter of 235 ± 15 nm and a polydispersity index (PDI) of 0.18 ± 0.02. Antimicrobial testing revealed inhibition zones of 17.0 ± 0.0 mm for Staphylococcus aureus, 15.0 ± 0.0 mm for Pseudomonas aeruginosa, 14.7 ± 1.2 mm for Escherichia coli, and 11.7 ± 0.6 mm for Salmonella enterica, indicating strong antifungal protection. The (PVP/G)/Cur nanogel coating extended strawberry shelf life to 6 days, compared to 4 days with a PVP–Cur coating and only 2 days for uncoated controls, representing a 200 % improvement in preservation time. These findings highlight the potential of this eco-friendly, scalable nanogel system for improving fruit preservation under adverse storage conditions.