Development of poly(ε-caprolactone)-based composite packaging films incorporated nanofillers for enhanced strawberry quality

The aim of the present study was to develop a packaging material for strawberry fruit by incorporating nanofiller such as graphene oxide (GO), graphene oxide modified with silane coupling agent (fGO), and titanium dioxide (TiO2) into a polycaprolactone (PCL) matrix using the solution casting method. In the first stage, graphene oxide was synthesized from graphite by the modified Hummers' method. Subsequently, the synthesized GO was modified with the silane coupling agent. PCL film, PCL/GO, PCL/fGO, PCL/GO/TiO2, and PCL/fGO/TiO2 nanocomposite films were eventually developed. The prepared films were characterized by structural, chemical, and thermal analysis by AFM, FTIR, XRD, DSC, TGA, water contact angle analysis and food packaging test. Structural and chemical analyses revealed that the synthesis and modification processes of GO were successfully achieved. The roughness values of the PCL/fGO and PCL/fGO/TiO2 films were found as 34.1 +/- 1.2 nm and 43.3 +/- 2.7 nm, respectively, which displayed a relatively smooth surface morphology compared to other films. The contact angle value for the PCL/fGO and PCL/fGO/TiO2 films sightly increased from 79.83 degrees to 80.34 degrees, respectively, with the addition of TiO2 to the matrix. The addition of GO into the polymer matrix increased the water absorption value of the PCL film to the maximum value of 19.64%; however, the addition of TiO2 nanoparticles decreased the water absorption value of the films by 14.62%. The results of the packaging test of strawberry fruit for 21 days demonstrated that the PCL/fGO/TiO2 nanocomposite film had the potential to be used as a food packaging film due to its ability to protect the freshness of strawberries.