Effect of Native Mucilage on the Mechanical Properties of Pectin-Based and Alginate-Based Polymeric Films

Abstract

Although the benefits of polymeric blend films have been well-established, mucilages’ interaction with other commercial bio-based polymers remains greatly unknown. Pectin and alginate were used to develop such polymeric blend films, with the addition of both ‘Algerian’ and ‘Morado’ cultivar freeze-dried, native mucilage precipitate. Mucilage additions at 0.25% and 1% (w/w), together with glycerol at 60% (w/w), influenced the mechanical properties of the 5% (w/w) pectin–mucilage and 5% (w/w) alginate–mucilage blend films differently. ‘Morado’ mucilage positively influenced the pectin film tensile strength (TS) and puncture force (PF) measurements, increasing the overall film strength compared to the homopolymeric pectin films. Calcium chloride (CaCl2) treatment and increasing mucilage concentration further enhanced the composite pectin–mucilage film strength. Contrasting results were obtained for alginate blend films compared to those of pectin. Studying the scanning electron microscope (SEM) images of the microstructures of CaCl2-treated pectin–mucilage and alginate–mucilage films confirmed superior microstructural film networks for pectin–mucilage films, which resulted in enhanced film strength, where the lack of polymer compatibility, as seen with alginate–mucilage, resulted in decreased film strength. These results indicate that native mucilage should be considered when developing such blend polymeric films, as it has the potential to enhance the films’ strength and elasticity.