Spectroscopic and molecular comparisons of three fractions from Acacia senegal gum

Gum Arabic: More Than an Edible Emulsifier

“…Although the total content of carbohydrate fractions of the three components is similar, as reported by Williams et al, 1990, it was found that protein-rich fractions have a significantly lower glucuronic acid content. Circular dichroism studies conducted on different GA fractions showed that only the AGP and GP components have a secondary structure (Renard et al, 2006).…”

“…A secondary fraction constituting 10% of the total, with a protein content of 11% and a molecular weight of 1400 kDa, corresponding to a complex Arabinogalactan-Protein (AGP) (Goodrum et al, 2000), and finally, iii. A smaller fraction (1% of total) composed by a glycoprotein (GP) consisting of the highest protein content (50 wt%) with an amino acid composition different from the complex AGP (Williams et al, 1990).…”

“…The highly branched structure of the GA molecules leads to compact relatively small hydrodynamic volume and, consequently GA will only become a viscous solution at high concentrations. Solutions containing less than 10% of GA have a low viscosity and respond to Newtonian behavior (Williams et al, 1990). However, steric interactions of the hydrated molecules increase viscosity in those solutions containing more than 30% of GA resulting in an increasingly pseudoplastic behavior.…”

“…In very acidic solutions, acid groups neutralize so inducing a more compact conformation of the polymer which leads to a decreased viscosity; while a higher pH (less compact molecule) results in maximum viscosity around pH 5.0-5.5. In very basic solutions, the ionic strength increment reduces the electrostatic repulsion between GA molecules producing a more compact conformation of the biopolymer and thus reducing the viscosity of the solution (Anderson et al, 1990;Williams et al, 1990).…”

Functions of Food Polysaccharides to Control the Gelatinization and Retrogradation Behaviors of Starch in an Aqueous System in Relation to the Macromolecular Characteristics of Food Polysaccharides

“…3.2.1 Molecular characterizations Molecular structures have been investigated in detail for SSPS (Nakamura et al, 2001(Nakamura et al, , 2002 and for GA (Al-Assaf et al, 2003;Islam et al, 1997;Randall et al, 1988Randall et al, , 1989Williams et al, 1990). As an experimental material, SSPS consisted primarily of galactose, galacturonic acid, and arabinose, in this order; whereas GA was abundant in galactose, arabinose, and glucuronic acid, in this order.…”