Characterization and Thermodynamic Properties of Acacia Oerfota Gum

Abstract

The physiochemical properties of Acacia Oerfota (old name A. Nubica) gum were studied. They include: moisture, ash, nitrogen hence the protein, pH value, specific optical rotation, acid equivalent and accordingly uronic acid, intrinsic viscosity and sugar composition. The results show that: moisture content is 9.25%, ash content is 1.6%, and nitrogen is 0.28%, protein is 1.8%, specific optical rotation is +74, pH is 4.9, acid equivalent is 2731 and intrinsic viscosity is 5.62 ml/g. The molecular weight of the sample was estimated using osmotic pressure measurements and found to be 4.85×106 g/mole. The cationic composition of Acacia Oerfota was determined and the result shows that Calcium was the most abundant cation in the sample (18.59 ppm) followed by Potassium (9.92 ppm), Magnesium (7 ppm), Sodium (5 ppm), Manganese (99 ppb), Lead (80ppb), Iron (66ppb), and Zinc (23 ppb). Sugar composition was estimated using HPLC technique where Arabinose, Galactose, and Rhamnose content were found to be 52.905%, 32.295% and 1.8% respectively. Thermodynamic parameters of A .Oerfota including the density, the partial specific volume of the gum solution and solvent (water) and the volume fraction were estimated and found to be 1.345gcm-3, 0.6420 cm3g-1 and 1.004 cm3g-1, 0.39004 and 0.60996 respectively. Chemical potential ranges of A. Oerfota have been calculated from osmotic pressure measurement for different concentration of gum solutions and were found to be -0.888×10-2to -1.1337×10-2 jg-1. Second virial coefficient (0.44×10-5) and free energy of mixing (-2.00×10-3 to -4.33×10-3 j g-1) were also determined.