This study determined the feasibility of using zinc oxide nanoparticles of various origins as an active compound for biopolymer packaging films. The study focused on the effects of green synthesis using passion fruit or tomato extracts and commercial zinc oxide nanoparticles on the physicochemical properties of pectin films, including thickness, microstructure, water content, optical properties, water vapour permeability, water contact angle, sorption properties, and thermal stability. Zinc oxide nanoparticles resulted in lower lightness, higher absorbance, especially in the UV light range, and increased transparency, from 1.55 to 2.18 a.u./mm. Films containing zinc oxide nanoparticles showed reduced water vapour adsorption but increased water vapour permeability, from 6.35 to 12.07 × 10−10 g/m·s·Pa. The initial water contact angles were in a similar range, from 57.3° to 59.2°, but a decrease in contact angle values was observed over 60 s. All films containing nanoparticles exhibited better thermal stability, particularly during the third stage of degradation above 200 °C. Developed composite active films, prepared from apple pectin and zinc oxide nanoparticles of different origins, showed their potential for practical use as UV-VIS light barrier packaging films or protective coatings for food applications.
Galus et al. (Tue,) studied this question.