Gelatin-Based Nanobiocomposite Films as Sensitive Layers for Monitoring Relative Humidity in Food Packaging

Gelatin-based nanocomposite films were prepared by casting and characterized as a sensitive hybrid material to relative humidity changes in the development of electrical sensors. Zinc oxide nanoparticles (ZnO-NPs) and glycerol (Gly) were incorporated as reinforcing and plasticizing agents, respectively, and their effects on the sensibility property of films were investigated. The proposed sensors were investigated at 25 °C. The behavior of gelatin-based films as a function of water presence was analyzed in terms of moisture content (MC), water vapor permeability (WVP), and water contact angle (WCA). The incorporation of ZnO-NPs and Gly induced morphological and structural changes in the composite films. Increased WCA (7.51%) and reduced WVP (18%) were observed for the nanocomposite films. In addition, ZnO-NPs and Gly significantly contributed to a further improvement of relative humidity sensibility of films compared to the control film. Electrical characterizations, carried out at different environments for gelatin-based films, revealed a positive responsive relative humidity behavior of materials and a sensibility of 99.47% for hybrid materials, suggesting the development of a new promising nanocomposite material for monitoring relative humidity conditions at 25 °C.