Properties of pectin-based films from white-fleshed pitaya (Hylocereus undatus) peel waste as affected by montmorillonite

Abstract

In this study, pectin was prepared from white-fleshed pitaya (Hylocereus undatus) peel waste to develop a novel biodegradable film, and the reinforcement effect of montmorillonite (MMT) on the films was investigated. The presence of MMT could lower the moisture sensitivity, which was reflected in the lowered moisture uptake capacity and water vapor permeability. The incorporation of MMT into the white-fleshed pitaya (Hylocereus undatus) peel pectin (WPPP) film improved the light-barrier property of WPPP films with the transmittance of ultraviolet and visible light reduced. The WPPP/MMT composite film might have a more compact structure and lower chain mobility, resulting in the improved tensile strength and decreased elongation at break when the content of MMT was 1–5 wt%. In addition, WPPP/MMT composite films demonstrated a higher thermal stability compared with the plain WPPP films. It was found that approximately 90% of the WPPP and WPPP/MMT films were degraded on the 15th days, suggesting their great biodegradability. The present study might demonstrate that pitaya peel waste pectin could become a novel film-forming polymer for edible or packaging films, and the incorporation of MMT was effective in improving the overall performance of films, as reflected by the enhanced tensile strength, thermal stability, and barrier properties to water vapor and ultraviolet as well as visible light, which might assist in the sustainable valorization of pitaya by-products.