Characterization of the properties of amphiphilic, alkaline soluble polysaccharides from sugar beet pulp

Abstract

This work characterized the physicochemical properties of two carbohydrate fractions, ASP1 and ASP2, that were sequentially extracted using NaOH and then NaOH/H2O2 from the pulp remained from the extraction of sugar beet pectin (SBP). It has been shown that ASP1 and ASP2 differed from SBP in terms of chemical and macromolecular features. The ability of the ASPs to stabilize oil-in-water emulsions containing 10% w/w oil was compared using SBP and gum arabic (GA) as reference emulsifiers. The volume weighted droplet size (d4,3 value) decreased as the concentration of SBP, ASP1, ASP2 and GA, increased in series 1.25, 1.5, 1.5, and 9% w/w and after which it remained constant except for ASP2 where the d4,3 increased at concentrations above 2.5%. At concentrations of 1.25, 1.5, 1.5, and 9% of SBP, ASP1, ASP2, and GA, critical d4,3 values of 0.55, 0.52, 2.14 and 0.55 μm were obtained, and droplet size for ASP2 was about 4 times greater compared with the other polysaccharides. The effects of pH (2–5) and ionic strength (Na+ or Ca2+, 0–100 mM) on the emulsifying activity at the critical concentration of the polysaccharide were studied. Emulsions stabilized by either ASP1 or 2 were unstable in the presence of Ca2+ due to the occurrence of bridge flocculation between oil droplets. It is concluded that ASP1 and ASP2 possess relatively inferior emulsification properties and, thus, are potential emulsifiers for use in low-calcium systems.