Application of Geraniol–Chitosan Blend Film with Quorum Sensing Inhibitory Activity as Packaging Materials for Biofilm Control in Fresh Fruit and Vegetable

Geraniol is an acyclic isoprenoid monoterpene phytochemical found in many essential oils. It is a GRAS (Generally Recognized as Safe)-approved food additive. In the present study, pure phytochemical geraniol was screened for quorum sensing inhibitory, antibiofilm and antibacterial activity against Chromobacterium violaceum and Pseudomonas aeruginosa PAO1 bacterial strains. Further, its biofilm inhibitory potential was confirmed against pathogens like Escherichia coli, Salmonella typhi, and Listeria monocytogenes. Geraniol was blended with chitosan biopolymer solution to develop an edible biodegradable film with anti-quorum sensing properties. At a concentration of 6.25% v/v of geraniol, violacein production was reduced by 79% in C. violaceum. A significant dose-dependent inhibitory effect was observed on QS-regulated phenotypes in P. aeruginosa PAO1. Biofilm formation at 2X-Minimal inhibitory concentration (MIC), i.e. 12.5% v/v and pyocyanin production at sub-MIC concentration, i.e. 3.125% v/v reduced by 81% and 69.19%, respectively. Geraniol also exhibited potential antibacterial activity against all the three tested pathogens. Further, the anti-adherence property of the film, after incorporation of geraniol in chitosan biopolymer (0.003 g/ml of chitosan solution), was examined through an in-vitro challenge assay for preventing attachment of E. coli on the carrot surfaces. Successful incorporation of geraniol phytochemical was confirmed with Fourier transform infrared spectroscopy (FT-IR) which reveals physical interactions between the active compound and functional groups of chitosan. X-ray diffraction (XRD) studies showed the characteristic crystallinity of both compounds. A tensile strength of 11.46 MPa indicated its barrier property as a packaging material. UV barrier property of the film was  approximately 69% represents its protective nature for light-sensitive food materials. Thus, from the obtained results, the suitability of using geraniol as active ingredients for the formation of edible films with different functional properties is confirmed.