Ar. Menzies et al., A COMPARISON OF THE PHYSICOCHEMICAL AND IMMUNOLOGICAL PROPERTIES OF THE PLANT GUM EXUDATES OF ACACIA-SENEGAL (GUM-ARABIC) AND ACACIA SEYAL (GUM TAHLA), Food additives and contaminants, 13(8), 1996, pp. 991-999
The physicochemical and immunological properties of three Sudanese gum
arabic samples and four gum tahla samples (two Sudanese, one West Afr
ican and one Tanzanian-Acacia seyal var. seyal) were compared. The opt
ical rotation (ca -30 degrees) and rhamnose (12-14%), arabinose (24-29
%), galactose (36-42%), glucuronic acid (16-17%), nitrogen (0 . 327-0
. 365%) and protein (2 . 16-2 . 41%) contents of the gum arabic sample
s were consistent with the FAO (1990) specification for Acacia gum. In
contrast the gum tahla samples had positive [alpha](D) values (+45 de
grees to +54 degrees), lower rhamnose (3-4%) and higher arabinose (41-
45%) contents and lower nitrogen (0 . 147-0 . 175%), and hence protein
(0 . 97-1 . 15%), contents. All of the gum arabic samples precipitate
d with beta-glucosyl Yariv reagent and hence were shown to contain ara
binogalactan-protein(s) (AGPs), whereas in all but one of the gum tahl
a samples AGPs were not detected. The strong interaction of gum tahla
with a monoclonal antibody known to recognize arabinose residues prese
nt in AGPs and arabinogalactans (AGs) was consistent with the observed
higher levels of arabinose present in the gum tahla samples relative
to the gum arabic samples. The data presented confirm that there are a
number of physicochemical and structural differences between gum arab
ic (A. senegal gum) and gum tahla (A. seyal gum), and that a quick and
simple immunological technique (immunodot blots) using an antiAGP/AG
monoclonal antibody (MAC 207) could be used to screen for the presence
of gum tahla in gum arabic consignments.