Physicochemical and Functional Properties of Glucuronic acid and Potassium Glucuronate from Acacia senegal var. senegal Gum

Abstract

Gum arabic (Acacia senegal) from Al Gadaref was used in this study. Physical and chemical properties such as moisture content, Total ash, pH value, intrinsic viscosity, Molecular weight, specific optical rotation, nitrogen and protein, acid equivalent weight, total glucuronic acid, and cationic composition were determined for gum Arabic. The values of moisture and ash were found to be 8.4 % and 3.2 % respectively, while the specific rotation value of the sample was found to be-27.5. The intrinsic viscosity of sample was found to be 15.3ml/g, while the calculated molecular weight value from Mark-Houwink equation was 4.85x105. The pH value was found to be 4.6. while nitrogen content was 0.227%. The calculated protein value from the conversion factor of 6.6 was found to be 1.5 %. The values of acid equivalent weight and percentage of total glucuronic acid were found to be 1700.7 and 11.4 % respectively. Results indicate that potassium is the major element present in Acacia senegal gum (1952.490ppm) when compared with calcium, sodium and magnesium. Glucuronic acid was prepared from Acacia senegal gum by the removal of metal ions using ion exchange chromatography. In addition Potassium glucuronate was prepared using glucuronic acid by titrating with potassium hydroxide solution. Glucuronic acid and potassium glucuronate gave pH values of 2.7 and 6.8 respectively. The values of moisture content were found to be 6.8% and 7.1% respectively, while the intrinsic viscosities were 10.8 and 12.9ml/g. The values of total ash were found to be 0.3% and 7.7% respectively. The specific optical rotation value of glucuronic acid and potassium glucuronate were found to be -20, -25 respectively. In addition the stability of Acacia senegal, glucuronic acid and potassium glucuronate emulsions with regard to type of oil (sunflower and groundnut) were also investigated. Results indicate that emulsion stability is significantly affected by the type of emulsifier and the type of oil used. Acacia senegal gum and potassium glucuronate formed more stable emulsions than glucuronic acid. Sunflower oil gave the most stable emulsions than groundnut oil.