Preparation and characterization of active cellulose-based papers modified with TiO2, Ag and zeolite nanocomposites for bread packaging application

Abstract

This study addresses the preparation and characterization of three active cellulose-based papers containing TiO2, Ag–TiO2 and Ag–TiO2–zeolite nanocomposites (P–TiO2, P–Ag–TiO2, P–Ag–TiO2–Z) and is aimed at use in bread packaging. It is organized in two parts: (1) the first part covers the morpho-structural characterization of nanocomposites and paper sheets (X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray) and explores some properties of the papers sheets (photocatalytic activity, wettability, barrier properties); (2) in the second part, the comparative efficiency of papers in the bread storage is discussed in terms of acidity, nutritional parameters (total fat, proteins and carbohydrates) and yeasts and molds charge. Morpho-structural investigations revealed a heterogeneous distribution of nanocomposites in the cellulose network as single particles or agglomerates. The higher content of active agents in the P–Ag–TiO2–Z positively affects the hydrophobicity, roughness, photocatalytic activity, opacity and water vapor permeability the most as compared to P–P (plain paper), P–TiO2 and P–Ag–TiO2. The free channels inside the zeolite structure result in the poorest barrier properties against air and grease of P–Ag–TiO2–Z and the highest food simulants–paper contact angles. Packaging tests indicate P–Ag–TiO2 as the most effective in the preservation of nutritional compounds in the bread. In return, P–Ag–TiO2–Z prolongs the microbiological safety of bread in terms of yeasts and molds content for 10 days at 20 °C and 12 days at 4 °C, 2 days longer than the second-ranked P–Ag–TiO2.