A COMPARATIVE STUDY OF SOME FUNCTIONAL PROPERTIES OF ACACIA GUMS

Abstract

A number of physicochemical methods were used to characterize different species of gums of Sudanese origin. Physical and chemical properties such as moisture, ash, intrinsic viscosity, specific rotation, nitrogen and protein percent, acid equivalent weight, total glucuronic acid, and total cationic composition were determined. The average values of moisture and ash percent of A. senegal var. senegal samples were found to be 13.49% and 3.27% respectively, while for A. polyacantha var. campylacantha samples they were 13.28% and 2.79% respectively. On the other hand the average moisture and ash values of A. seyal var. seyal samples were 9.30% and 2.61% respectively . The average specific rotation value of A. senegal var. senegal samples was found to be(-32)0, while for A. polyacantha var. campylacantha samples it was found to be(-19.30)0, while for A. seyal var. seyal samples it was (+49.4)0 on average. The determined intrinsic viscosity average value of A. senegal var. senegal samples was found to be 14.61ml/g, while for A . polyacantha var. campylacantha samples the average was 9.15ml/g and for A. seyal var. seyal samples it was found to be 11.40ml/g. Kjeldahl determination of nitrogen content revealed an average of 0.35% and 0.36% for A. senegal var. senegal and A. polyacantha var. campylacantha samples respectively, while for A. seyal var. seyal samples the average was to 0.14%. The calculated average protein values using a conversion factor 6.6 were 2.31%, 2.394% and 0.931% for A. senegal var. senegal, A. polyacantha var. campylacantha and A. seyal var. seyal respectively. The values of acid equivalent weight and percentage of glucuronic acid were found to be 1161 and xiv 15.2% on average respectively, for A. senegal var. senegal samples. For A. polyacantha var. campylacantha samples the values were 1280.6 and 13.8% respectively. On the other hand for A. seyal var. seyal samples acid equivalent weight average value was found to be 1107.9, while percent glucuronic acid value was 15.9% on average. Different dry and wet ashing methods were used to determine the cationic composition of the studied gum samples. It was found that Ca, Mg, Na, K, Fe and Cu were the major elements present in all samples. It was also found that removal of total cations did not alter properties such as specific rotation and intrinsic viscosity significantly . Four fractions of gum samples were obtained by solvent fractionation using absolute ethanol. The fractions were found to have varying amounts of protein and different values of intrinsic viscosity and specific rotation suggesting some variation in the molecular structure after fractionation . The emulsification properties of Gum Arabic with some grains and fruits used in local beverages in Sudan, Barley(Hordeum vulgare), Aradeib fruits (Tamarindus indica) and Tabaldi fruits (Adansonia digitata ) were studied. It was found that Gum Arabic improves the emulsification time of these grains and fruits, however this improvement is affected by addition sugar but does not change by changing the ionic strength of the solution.