Studies on uronic acid materials

Abstract Some of the analytical parameters for Acacia senegal gum have been determined for ( a ) twelve “bulk” samples of tapped gum from three different districts of the Sudan, and ( b ) thirteen, different, single-nodule specimens of “natural exudate” gum. These samples show the same range of analytical variation that has been noted previously for samples of gum from other Acacia species. In addition, the following atypical variants of Acacia senegal gum have been studied: ( a ) three specimens of “non-nodular” gum, ( b ) a sample from a tree infested with wood-boring beetles, and ( c ) a sample of “Hennawi” gum, a dark-colored, sweet-tasting gum from the main stem of trees. The viscosity data obtained indicate that values of M w for the samples fall in the range 0.26 × 10 6 to 1.16 × 10 6 ; this explains the lack of agreement for M w of A. senegal gum samples studied by earlier investigators. The atypical, non-nodular and beetle-borer specimens of gum do not show any striking analytical differences from the mean values obtained for the typical samples. The “Hennawi” variant differs from typical, tapped samples in two important respects: the uronic acid residues present in the free acid form are fewer in number, and the rhamnose content is considerably less.