Characterisation and authentication of A. senegal and A. seyal exudates by infrared spectroscopy and chemometrics.

The authentication of Acacia gums samples requires usually the use of sophisticated and time consuming analytical techniques. There is a need for fast and simple analytical techniques for the objective of a quality control methodology. Commercial Acacia senegal and Acacia seyal gums present characteristic MIR spectra. Principal Component Analysis of the infrared spectra of gum exudates of trees allow to distinguish Acacia gums from another gum exudates (Combretum, Ghatti, Karaya, Tragacanth). Moreover, gums of A. senegal and A. seyal separate them and from other Acacia species (Acacia dealbata, Acacia karoo, Acacia nilotica, Acacia sieberiana). Chemometric treatments of A. senegal and A. seyal MIR spectra were assessed for the quantification of moisture content in Acacia gums, for the classification into the two species and for the adulteration detection and quantification. Results were quite satisfactory, the moisture content was estimated at 3.1%, adulteration was detected at 3.4% and quantified at 5.6%. The discrimination of the two species is done without any ambiguity.