Sugar beet pectins (SBPs) are known for their emulsifying properties, but it is yet unknown which structural elements are most important for functionality. Recent results indicated that the arabinose content has a decisive influence, but the approach applied did not allow causality to be established. In this study, a mostly intact SBP was selectively modified and the obtained pectins were analyzed for their molecular structure and their emulsifying properties. De-esterification only resulted in a moderate increase in droplet size. The length of the pectin backbone only influenced the emulsifying properties when the homogalacturonan backbone was cleaved to a higher extent. By using different arabinan-modifying enzymes, it was demonstrated that both higher portions and chain lengths of arabinans positively influence the emulsifying properties of SBPs. Therefore, we were able to refine the structure-function relationships for acid-extracted SBPs, which can be used to optimize extraction conditions.
Keywords: acetylation; emulsion stabilization; enzymatic modification; methylation; structure−function.