Optimized Multifunctional Chitosan/Gelatin Nanocarriers for Sustained Release of Cinnamon Essential Oil and Microbial Control

Nanoparticulate carrier systems composed of chitosan and chitosan/gelatin blends encapsulating Cinnamomum zeylanicum essential oil were developed and optimized using ionic gelation. Process parameters, including crosslinker concentration, surfactant type, polymer/oil ratio, mixing speed, and chitosan/gelatin ratio, were systematically evaluated. Chitosan-only carriers achieved 25.18% +/- 0.01% encapsulation efficiency and 30.19 +/- 0.01 mg/g oil retention, while gelatin incorporation enhanced performance to 80.89% +/- 0.07% efficiency and 78.89 +/- 0.03 mg/g retention. Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed successful oil encapsulation, while scanning electron microscopy revealed spherical nanocapsules (48.48-75.45 nm), with size increasing alongside gelatin and oil content. In vitro release studies demonstrated up to 85% oil release over 4 days, with faster release in gelatin-containing systems. Antimicrobial efficacy was evidenced by 6 days of microbial growth inhibition on strawberries. Cytotoxicity assessment using the MTT assay on L929 fibroblasts confirmed the proliferative effect and the absence of cytotoxicity of the nanocarrier system. Nanoparticles retained over 80% of their oil load after 90 days of storage at -20 degrees C, highlighting their potential for sustained delivery of essential oils.