Novel food preservation strategy using sprayed PVA/chitosan-based coatings activated by macroemulsions of chamomile essential oil adsorbed on activated carbon

Active films based on polyvinyl alcohol (PVA) and chitosan (CS) were developed by encapsulating chamomile essential oil using an emulsification process, followed by adsorption onto activated carbon (AC) to stabilize the oil droplets. Microscopic analysis showed that the average size of the micelles was between 0.1 μm and 1.5 μm. The micelles obtained were incorporated into PVA/CS film formulations with different concentrations of chamomile essential oil (5 %, 10 %, 15 % w/w), and the optical, physical, mechanical, antibacterial, and antioxidant properties as well as the release rate of the encapsulated oil were studied to test their application in food packaging. The SEM images showed a homogeneous dispersion of the EO in the polymer matrix containing AC, due to the formation of hydrogen bonds, which is confirmed by the FTIR results and is accompanied by an increase in the viscosity of the film-forming solutions, a decrease in the crystallinity and an improvement in mechanical properties by an increase in elongation at break (15.95 ± 0.10 to 47.02 ± 0.06 %) of the films produced. In addition, some properties of the PVA/CS films were increased by the addition of EO-AC, notably thickness (0.097 ± 0.12 to 0.144 ± 0.01 mm) and opacity (1.632 ± 0.11 to 8.266 ± 0.12), while the water absorption rate and solubility of the films decreased. PVA/CS-EO-AC films exhibit good antioxidant and antibacterial activity against E. coli and S. aureus, high barrier properties (UV-blocking) and a controlled release of bioactive molecules contained in EO. The PVA/CS/EO-AC coating reduced the weight loss of the tested apples to (3.31 ± 0.29 %) compared to apples packaged in polyethylene film, and maintained their appearance after 3 weeks of storage. These results offer the possibility of reducing food waste through this new coating strategy based on the encapsulation of EO.