THE CLASSIFICATION OF NATURAL GUMS .2. CHARACTERIZATION OF THE GUM-ARABIC OF COMMERCE BASED ON A CHEMOMETRIC STUDY OF AMINO-ACID COMPOSITIONS

Commercial samples of gum arabic from Ethiopia, Senegal, Nigeria, Chad and Sudan have been compared with authenticated A.senegal (L.) Willd. specimens from Mauritania, Mali, Senegal, Ethiopia and Oman using a c hemometric analysis based on their amino acid compositions. The majori ty of these form a cluster which encompassed both normal geographic an d commercial variability. The three samples outside the cluster posses s chemical or taxonomic features which account for their exceptional b ehaviour. For comparison, Acacia gums from non-African sources (Phyllo dineae Benth.) and the Leucaena gums from Hawaii and Mexico, which are closely related chemically and physically to gum arabic were analysed also by principal component analysis. These gums can be identified in dividually and distinguished from commercial gum arabic. It is propose d that chemometric methods could provide a basis for setting commercia l specifications for gum arabic, which would take account of the antic ipated variability of this complex natural product and eliminate the p ossibility of serious adulteration by unacceptable related gums of ara binogalactan protein origin.