Functionalisation of Pectin by Ultra High Pressure Homogenisation

Abstract

Pectin is well-known plant-based hydrocolloid extensively used in food and beverage industry for formation and/or enhancement of product texture and stability. Versatile functionalities of different pectin types (e.g., gelling, thickening, colloidal stabilization) are predetermined by their structure. The aim of this work was to explore possibility to alter structure of pectin by pilot-scale ultra-high dynamic pressure treatment, as a physical modification approach, and potentially enhance its functionality. High esterified unstandardized apple (AU) and citrus pectin (CU) solution (2.5% (m/m)) were treated by ultra-high pressure homogenizer (UHPH) at three different pressure levels and characterized with respect to their apparent viscosity, gelling behavior (gelation time, temperature and melting point), gel strength, molecular weight (MW) and on-line viscosity using size-exclusions chromatography coupled to refractive index, light scattering and online differential viscometer. The results indicated that UHPH impacted the MW in a source dependent manner. Treated CU and AU pectin exhibited a small decrease in the average MW and a more pronounced decrease in the intrinsic viscosity, likely due to more significant UHPH effect on the larger pectin molecules. In addition, the smaller (in volume) AU pectin presented a more compact conformation in solution. On the macroscopic level, those changes resulted in statistically significant decrease in apparent viscosity. UHPH CU pectin exerted decrease in gelation time and increase in gelation temperature, but not on statistically significant level. Even though treatment caused decrease in apparent viscosity of CU and AU pectin it had no effect on their respective gel strengths. From the obtained results, it can be concluded that UHPH process has a potential to modify the structure and flowing behavior of pectins, but further research is needed in order to elucidate all the changes in pectin functionality and potential benefits of this ubiquitous and multifunctional hydrocolloid treated by UHPH.