Physicochemical and functional properties of cross linked and high pressure homogenized sugar beet pectin: A comparative study

Chemical cross-linking and high pressure homogenization are two methods to improve techno-functional properties of pectin. In this study, the effect of high pressure homogenization (HPH) variables including pressure (200, 600 and 1000 bar), numbers of passes through homogenization valve (1, 3 and 5 times) and pH (3.1, 3.6 and 4.1) on viscosity, water holding capacity (WHC), oil holding capacity (OHC) and emulsion properties of sugar beet pectin were studied. The functional properties of pectin improved at higher homogenization pressure, more numbers of passes and lower pHs. Cross-linking, as a traditional chemical modification was also performed with the presence of 1, 2, 3, 5% pectin reacting with ammonium persulfate. The degree of esterification (DE) and Mw of pectin increased for 1–3% reactant pectin followed by a decrease for 5% of pectin due to steric hindrance. The Fourier Transform Infrared (FTIR) and ferulic acid content confirmed the changes in cross-linking efficiency. It was also revealed that HPH could break the cross-bonds between ferulic acids and reduce the ferulic acid dehydrodimer. The maximum emulsion stability of cross-linked pectins was obtained for 3% reactant pectin while it was still lower than that of optimized HPH treated pectin. X-ray diffraction showed amorphous structure of pectin with no considerable change after chemical or mechanical modification. Scanning electron micrographs indicated more profound impact of HPH treatment on surface properties of pectin rather than cross-linkage. However, HPH treatment reduced the thermal stability of pectin in contrast to cross-linking modification. [Display omitted] •High homogenization pressure and cycles and low pH enhanced pectin functionality.•HPH treatment broke crystalline structure and ferulic acid cross-links.•HPH treated pectin showed better functional properties than cross-linking ones.