Fractionation; Physicochemical and Functional Properties of Acacia Polyacantha Gum.

Abstract

Fourty samples of A. polyacantha gum were collected as natural exudate the inform nodules from A. polyacantha trees from Kadogli forests (South Kordofan State) and Eldamazine (Blue Nile State) during the season 2005/2006. Twenty samples were collected from each site. The gum samples were subjected for physicochemical and functional tests. The mean specific rotation of Kadogli samples was -19.6°, while that of Eldmazine was -14°, intrinsic viscosities were 9.9 and 10.2 ml/g for Kadogli and Eldamazine samples, respectively. Refractive indices of all samples from the two different locations showed the same value of 1.3354. The mean value of the emulsifying stability of samples from Kadogli was 0.99200 while that from Eldamazine was higher (1.06540). The water holding capacities of all tested samples were in the range 63.0 - 63.9%. The two sources of samples gave approximately the same average moisture (10.5%) and ash (3.4%) contents. Nitrogen content of Kadogli samples was 0.30 to 0.42% (1.88 to 2.63 % protein), while that of Eldamazine samples was 0.36 to 0.48% (2.30 to 2.90% protein). The mean concentration of reducing sugars was 0.23 and 0.16% for Kadogli and Eldamazine samples, respectively. Uronic acid contents of Kadogli samples ranged from 12.02% to 17.30 % and that of Eldamazine samples ranged from 12.10% to 19.48%. Location significantly affected uronic acid content. The mean pH value for Kadogli samples (4.96) was lower than that for Eldamazine samples (5.23). The mean value of the equivalent weight for gum from Kadogli (1397.90) was found to be higher than the value of 1280.20 for Eldamazine samples. On the other hand, Eldamazine samples gave lower average molecular weight of 3.20×103 compared to value of 3.29×103 for Kadogli samples. With respect to the mineral contents, gum samples from the two sources showed the same range of 35 to 70 _6;g/g sodium. Whereas gum samples from Kadogli recorded higher potassium in the range of 0.075 to 0.135 _6;g/g, compared to the range of 0.025 to 0.095_6;g/g related to gum samples from Eldamazine. Calcium content was 0.330 - 0.666 _6;g/g without significant differences between the two locations. Gum samples from Kadogli and Eldamazine were found to contain 0.165 - 0.291 and 0.176 - 0.263 _6;g/g Mg, 20.3 to 28.1 and 20.1 - 56.2 _6;g/g Fe, respectively. Solutions of fractions 1 and 2 showed -22o and -16o specific rotation, 1345.11 and 1530.20 equivalent weight, 3.37×103 and 2.77×103 molecular weight, 10.5 and 9.43 ml/g Intrinsic viscosity, respectively. Interestingly the two fractions gave the same refractive index of 1.3354. Fraction 1 showed significantly (p X04; 0.05) lower moisture, ash and nitrogen (6.6%, 2.67 and 0.35%, respectively) compared to Fraction 2 (15.45%, 3.75 and 0.38%, respectively). On the other hand Fraction 2 showed significantly (PX04; 0.05) lower uronic acid, pH, Emulsifying stability and conductivity (12.11%, 2.9, 0.83432 and 0.728µ/s, respectively) compared to Fraction 1 (14.2%, 4.7, 1.11211 and 151.21 µ/s, respectively). The sugar components of the whole gum and its fractions were determined in acid hydrolysated by chromatography. L+arabinose, L+rhaminose and D-galacturonic acid were detectable. These observations were confirmed by high performance liquid chromatography (HPLC) and showed that A. polyacantha gum contained 1.5 and 0.49 mg/100g L+Rhaminose and L+Arabinose, respectively. On the other hand, L+Rhaminose was found to be 7.98 and 8.1 mg/100g for Fraction1 and Fraction2, respectively. The two fractions showed negative result for L+Arabinose, D-Glucose and D-Mannose. The spectral measurements of ultra violet (UV) and infra red (IR) were scanned for gum samples and their fractions.