Intra-species variation of the properties of gum exudates from some Acacia plants

This thesis reports on the inter- and intra-species variation of the physicochemical properties of gum exudates from six Acacia species and six commercial Acacia gum samples from Tanzania. A comparison of the results with regulatory bodies’ specifications for gum Arabic for food and pharmaceutical use as well as Sudanese Acacia gums is also presented. The physicochemical properties of the authenticated gum samples have shown both inter and intra-species variations. Whereas eleven parameters namely, ash content, viscosity, absorbance, specific optical rotation, methoxyl content, tannin content, solubility, PH, % salt form. Acid Equivalent Weight and nitrogen content, have shown to vary significantly from species to species, only eight parameters (absorbance, viscosity, Acid Equivalent Weight, specific optical rotation, tannin, solubility and PH) Have shown significant intra- species variations of the properties of the authenticated gum samples means that the variation of the properties of Tanzanian commercial Acacia gum is due to both admixture of gums from different Acacia species as well as variations of properties among gums from the Acacia species (intra-species variation). The properties of the gum exudate from A. senagal var. leiorhachis differ from that obtained from A. Senegal var.senegal (widely accepted as the source of commercial gum Arabic) by being far less soluble, much more viscous and having higher methoxyl and nitrogen contents. Most of the physicochemical properties of the gum exudates from A. seyal var. seyal and A. seyal var. fistula are similar and it is justifiable to retain them as variants of the same species. Tanzanian commercial Acacia gum samples analyzed in this study have shown that the gum is comparable to Sudanese commercial Acacia gum except that it is less viscous dextrorotatory and contains a small amount of tannin. This work has also proposed quality control boundaries for some parameters for Tanzanian commercial Acacia gum.