Chicory root pulp pectin as an emulsifier as compared to sugar beet pectin. Part 1: Influence of structure, concentration, counterion concentration

Abstract

The emulsifying properties of a pectin product vary with its origin. In this work, the structural and emulsifying characteristics of a low-methylated and partially acetylated pectin from chicory root pulp (referred to as CRP) were investigated and used in comparison with sugar beet pectin (SBP). The structural characterizations suggested a few aspects of dissimilarity between CRP and SBP: (a) GalA content, (b) composition of neutral sugars (NS), (c) weight average molecular mass, (d) protein content and amino acid composition, and (e) ferulic acid. CRP was interface-active and thus comparable to SBP in the stabilization of the oil/water emulsion formulated with 15% middle chain triglyceride (MCT). Upon increasing the concentration from 0.25 to 2% w/w, similar downward trends of d32 were observed for CRP and SBP, however, CRP showed relatively better performances at 0.25 and 0.5%. The minimum d32 values for CRP (0.58 ± 0.02 μm) and SBP (0.54 ± 0.02 μm) were achieved at critical concentrations of 1.5% and 2%, respectively. At these critical concentrations, the distribution of droplet sizes of the corresponding emulsions was significantly different. The emulsifying ability of CRP depended largely on the covalently bound proteinaceous moiety, whose contribution was demonstrated by proteinase induced demulsification. The effect of Na+ and Ca2+ on emulsification was also examined; both CRP and SBP were almost unaffected by the addition of Na+ (25–100 mM), whereas CRP was more sensitive to the addition of Ca2+ (25–100 mM). For CRP, the stronger responsiveness to Ca2+ may be due to the weaker hindrance of the acetyl groups. Altogether, we conclude that CRP can be used as a polysaccharide-based emulsifier, particularly for use in stabilizing low-calcium emulsion systems.