New quaternary ammonium derivatives (quats) based on apple pectin (PA) were synthesized by the chemical modification of native polysaccharides with various quaternization mixtures containing epichlorohydrin (ECH) and a tertiary amine. Pectin derivatives (QPAs) were studied by elemental analysis, conductometric titration, Fourier-transform infrared spectroscopy (FTIR), and 13C nuclear magnetic resonance (13C NMR). Viscosity measurements enabled the evaluation of the viscosity average molar mass (Mv) for the unmodified polysaccharide, as well as its intrinsic viscosity ([η]) value. Dynamic light scattering (DLS) analysis revealed that the PA and its quats formed aggregates in an aqueous solution with either a unimodal (PA) or bimodal (QPAs) distribution. Scanning transmission electron microscopy analysis (STEM) of the PA and its derivatives demonstrated the presence of individual polymeric chains and aggregates in aqueous solution, with the smallest sizes being specific to amphiphilic polymers. Thermal stability, as well as wide-angle X-ray diffraction (WAXD) studies, generally indicated a lower thermal stability and crystallinity of the QPAs compared with those of the PA. Antipathogenic activity demonstrated that the PA and its derivatives exhibited effectiveness against S. aureus ATCC 25923 bacterium and C. albicans ATCC 10231 pathogenic yeast.
Keywords: antipathogenic activity; apple pectin; quats.