Spider web-reinforced chitosan/starch biopolymer for active biodegradable food packaging

In this study, starch (ST), chitosan (CH), spider silk (SW), and their hybrid composite bioplastics were fabricated and examined for physicochemical and mechanical properties. The essential oils (EOs) of Rosmarinus officinalis were encapsulated to enhance their biological application. The prepared composite films were characterized using various spectroscopic techniques such as XRD, SEM, GCMS–, UV–VIS, TGA, and FTIR spectroscopy. The antimicrobial activity of the prepared film was tested against S. aureus bacterial and C. albican fungal strains which showed a greater zone of inhibition for the composite film encapsulated with EOs. The biodegradability of the synthesized film was evaluated for 60 days in soil under laboratory conditions. The composite film containing spider web and essential oil significantly improved mechanical properties. The physicochemical results, such as moisture, solubility, swelling, transmittance, opacity, and water vapor permeability, of the prepared bioplastic were comparable with those of the control plastic. The EO-based film had greater antioxidant activity against DPPH, hydrogen peroxide, and phosphomolybdenum assays, with an inhibition range of 60–70 %. The addition of spider web and essential oil to the chitosan/ starch film significantly increased the shelf life of injera and tomatoes for 7 and 10 days, respectively for the EO-based film. The biodegradability of the synthesized film has shown a great reduction in the weight and growth of microorganisms. In general, the CH/ST/SW and CH/ST/SW/EOs composite films have greater mechanical, biological, physicochemical, and potential improvement of food shelf life applied as either coating or packaging material.