Physicochemical Characterization of Gum Exuded From Prosopis Cineraria and Prosopis Glandulosa Species of Thar Desert Pakistan

Prosopis cineraria and prosopis glandulosa torryana wildly growing trees in Thar Desert Pakistan exude gum in appreciable quantities. The climatic conditions of desert catalyze gum exudation from trees and may affect their quality characteristics. No research work has been carried out to characterize these valuable gums and evaluate their potential for commercial exploitation. In the present study 135 samples (16kg) of P.glandulosa gum and 87 samples (9kg) of P.cineraria gum were collected and studied for their physicochemical properties. P. cineraria gum was sorted in three classes as amber, light yellow having dull luster and transparent golden yellow shades. P.glandulosa gum samples were sorted as dark brown and light brown samples. Among the physicochemical characteristics studied, moisture content of all classes of gums varied between 8-14%, ash 3-9%, protein 10 -21%, insoluble matter 0.8 - 1.9%, and the tannin content of transparent golden yellow samples of p.cineraria gum as 0.3-0.6%. The tannin content p. glandulosa was found to be fairly high making it unsuitable substitute of gum for food applications. All the samples were found to be dextrorotary and showed lower pH values. The intrinsic viscosity of gum samples ranged between 10.6- 13.6 ml/g and the values were used to calculate viscosity average molecular weight of gum samples. All the samples were found to be rich in amino acid content having Hydroxyproline between 300-380, tyrosine 270- 326, aspartic acid 170-210, and serine 170-195 residues per 10000 residues. Cationic composition of ash of gum samples revealed calcium magnesium sodium and potassium as major cations whereas no presence of toxic metals lead cadmium and mercury was detected. Comparative assessment of data indicated that P.cineraria gum was of better quality as compared to that of P. glandulosa and that the application of classification procedure has marked effect on gum quality and potential to make p. cineraria gum as suitable substitute of gum arabic.