Air fractionation and physicochemical properties of the fractions from Acacia polyacantha gum

Abstract

In this study, Acacia polycantha gum solution (12.7%) was fractionated by a foaming method using aerating pump into two fractions .The first is the hydrophobic fraction(HO) which is high protein fraction and the second is the solution remaining after the fractionation operation which has been freeze drying (hydrophilic fraction) .then an analytical study on fractions was done to explain physical and chemical properties such as nitrogen content , protein content, ash content, moisture content, intrinsic viscosity, PH value, number average molecular weight , specific optical rotation, and refractive index. Also spectroscopic study was done to determine cationic composition such as sodium, calcium, magnesium, potassium and iron. At last comparative the results of the fractions with previous study for crude polyacantha gum and the results as following: A proximate analysis of two fractions(HO , HI) and crude gum respectively revealed that, moisture content(10.29, 8.4 and ,7.5%),whereas the ash content (2.85 ,3.4and 3%) , specific rotation(24-, -18 and- 17.3),refractive index(1.685, 1.685, 1.337) and nitrogen content ( 0.56, 0.35,and0.35%)were significantly different. Protein content(3.6, 2.31 and, 2.28%), PH value(4.65, 3.1 and 4.9) and the intrinsic viscosity (0.7807, 0.422 and 10.3ml/g)were, highly, significantly different. Also number average molecular weight for tow fractions obtain from osmometer results (HI fraction =148,274 g/mole) and (HO fraction =76,310g/mole) ,while the average molecular weight for crude gum = 136,900 g/mole ,the high molecular weight and high solubility were indicate that Acacia polyacantha gum is high branched . Also UV absorption spectra of two fractions were determined and maximum were found to be a proximately the same, that indicates similar chemical structure. Cationic composition of two fractions was studied. Na, K and Ca by flame photometer, Fe and Mg by atomic absorption spectroscopy , the results obtained( K) is the highest value(HI =130.125 , HO = 109.05μg/g)Followed by Ca ( HI = 100.92 , HO=90.99μg/g) , Na (HI= 39.75, HO= 7.107μg/g ), Mg ( HI =14.915 , HO =15.392μg/g) and Fe ( HI = 2.4031, HO = 1.583μg/g) , while the crude gum contains high of Na and Fe than value in fractions and low value in K ,Mg and Ca .