Emulsion stabilizing properties of pectins extracted by high hydrostatic pressure, high-speed shearing homogenization and traditional thermal methods: A comparative study

In the previous studies, two novel methods for pectin extraction, using high hydrostatic pressure (HHP) and high-speed shearing homogenization (HSHE), were developed with higher efficiency, less time and energy consumptions than traditional thermal extraction (THE); however, many functional properties of these pectins are still unknown. To explore the influence of extraction methods (HHP, HSHE and THE) and pH on the emulsion stabilizing properties of these pectins, many parameters, including zeta potential, apparent viscosity, light microscopy, and particle mean diameters of pectins or their emulsions (1% pectin with 42.8% refined soybean oil), were firstly determined compared with those of two commercial pectins (AP and SP). The results revealed that extraction methods have important influence on viscosities of pectins and their emulsions. The emulsions prepared by HHP extracted pectin have the smallest particle mean diameters (8.96–11.02 μm) and best emulsifying stability (100%) after centrifugation assay or 3 weeks of storage at 4 °C with the pH in the range of 3–5. The emulsions prepared by HSHE and THE extracted pectins have a similar particle mean diameters and emulsifying stabilities better than those made with AP and SP. The molecular weight distributions and morphological features, determined by HPSEC-RID and AFM, then indicated their difference at molecular level and their interactions. From the results, it could be concluded that emulsion stabilizing properties of pectin were greatly influenced by their physicochemical properties, including viscosity, molecular size and their interactions.