Physicochemical and biological evaluation of 'click' synthesized vinyl epoxide-chitosan film for active food packaging

Abstract

Chitosan (Cs) being a natural biopolymer serves as an excellent template to construct active packaging materials for achieving sustainable development. In this study, Cs was chemically modified via epoxide ring opening click reaction using vinyl epoxide to obtain a novel chitosan vinyl epoxide (Cs-VE) derivative with hydroxyl and olefinic functional groups. The Cs-VE transparent film was fabricated through the eco-friendly solution casting technique. A meticulous investigation into the chemical structure and physicochemical properties of the synthesized films was conducted using FT-IR, ¹H NMR and XRD analyses. The thermal stability and homogeneity of the film were verified by thermogram and FE-SEM images respectively. Improved mechanical properties (tensile strength of 24.64 MPa and 12.08 % elongation at break) and excellent UV-light blocking ability (9.3 % transmittance at 350 nm and 22.15 % transparency at 600 nm) were observed. Also, important parameters such as water vapor permeability (WVP), swelling degree, water solubility and UV-barrier properties were found to be adequate for food packaging application. Similarly, enhanced antioxidant activity with 27.2 % and 73.6 % radical scavenging against DPPH and ABTS radicals respectively was observed for the synthesized Cs-VE film. The film showed antimicrobial activity against both bacteria and fungi. These results along with food packaging studies on Grewia asiatica fruit established the developed Cs-VE film as a suitable candidate for active food packaging application.

Keywords: Antimicrobial activity; Antioxidant property; Chitosan; Click chemistry; Food packaging; Vinyl epoxide.