PHYSICOCHEMICAL CHARACTERIZATIONS OF ACACIA SIEBERANA VAR. SIEBERANA OF SUDANESE ORIGIN.

Twenty four authentic samples of Acacia sieberana var. sieberana were collected from South Kordofan (SK) and White Nile (WN) states. The samples were analyzed to determine average values, of moisture, ash, pH, specific rotation, refractive index, number average molecular weight, intrinsic viscosity, nitrogen content, protein content, total uronic acid and acid equivalent weight of the gum. For (SK)samples average values, for the above parameters, were found to be: 8.56 %, 1.61%, 4.34, +104°, 1.337, 2.13× 106 Da, 8.56 ml /g, 0.37%, 2.45%, 9.2% and 1933 respectively, while those of WN samples were found to be: 9.12 %, 1.65%, 4.38, 103, 1.337, 2.29× 106 Da, 9.39 ml /g, 0.37 %, 2.43%, 9.4 % and 1884 respectively. The cationic composition showed the following sequence: calcium > potassium> magnesium > sodium. Traces of: Fe, Ni, Co, Mn, Cu and Pb were detected. Percent average values of sugar composition show that galactose, arabinose, rhamanoe, glucuronic acid and 4-O-methylglcuronic acid for the gum samples from both locations are similar. For SK samples the values were found to be: 9.8, 57, 4.0, 2.7 and 6.5 respectively, while those of WN samples were found to be: 9.9, 56, 3.1, 2.4 and 6.6 respectively. The molecular weight distributions, of two composite samples, of the gum from the two locations indicate the presence of three main fractions. The weight average molecular weight of SK and WN, composite samples, is 1.8 ×106 Da and 1.6 × 106 Da respectively. The emulsifying capacity study of the gum shows that the gum is a grade one emulsifying agent.