Characterization, Fractionation and Functional applications of the Gum from Acacia oerfota

Abstract

Thirty samples of the gum from Acacia oerfota were collected from two locations (15 sample from each location) from around Senga - Sinnar state and Wadel hadad - Aljazeera state - Sudan, during season 2015. Four composite sample was made for the fifteen samples for each location by mixing. Chemical, physicochemical, rheological behavior, molecular weight and molecular weight distribution, and emulsification properties of Acacia oerfota gum were conducted. The results show the ranges for moisture content (11.8 - 13.1%), Ash content (1.12 - 1.40%), pH (4.55 - 5.28), specific optical rotation (+65 to +80), color Gardena (0.1 - 0.3), nitrogen content (0.35 - 0.77), hence protein% (2.19 - 3.93%), tannin (268 - 292 ppm), acid equivalent weight (2941 - 5357), total uronic acid% (3.62 - 6.60%), intrinsic viscosity (3.94 - 10 cm3g-1), and calorific value (~ 4 kJ/mole). Cationic composition % of Senga location are Calcium 0.287, Potassium 0.131, Strontium 0.004, Iron 0.010. While the caionic composition % of Wadel hadad location are Calcium 0.242, Potassium 0.145, Strontium 0.005, Sulphur 0.002, and Iron 0.001. The rheological behavior of A. oerfota gum show a Newtonian behavior (the molecular shape is reestablished when applied stress is removed). The values of number average molecular weight (Mn) of A. oerfota gum ranges between 1.68x105 and 1.80x105 g/mol for the two composite of Senga and Wadel hadad locations respectively. The molecular weight determined by gel permeation chromatography (GPC-MALLS) for the two location was found to be 6.23x105 and 9.59x105 g/mole. Acacia oerfota gum samples collected from Senga location show three fractions; Arabinogalactan protein (AGP) with molecular weight of 4.77x105 mass% 1.11, and Rg 50 . The second and third fractions are (Arabinogalactan AG + Glycoprotein GP) have molecular weight of 5.76x105 g/mole , mass% 98.89. GPC-MALLS for A. oerfota gum samples collected from Wadel hadad shows an AGP with a molecular weight of 4.19x105, mass% 0.84, and Rg 187. The second and third fractions are (AG +GP) have a molecular weight of 8.24x105 g/mole , mass% 99.16 . All emulsions show large droplets size, exhibit a typical bimodal droplet size distribution with a pronounced shoulder reflecting bad uniformity and unstable emulsions