Botanical and commercial characterisation of gum arabic and its detection in wine using non-targeted high resolution mass spectrometry

Gum arabic (GA) is the oldest and best known of all natural gums. Thanks to the particular characteristics resulting from its complex mixture of polysaccharides and glycoproteins, its field of application is extensive. In the oenological sector, it is used to prevent colour depigmentation and protein precipitation and although there is no declared limit, the International Code of Oenological Practices suggests not exceeding a dosage of 300 mg L−1. In this study, the botanical origin (Acacia senegal vs A. seyal) and commercial description (Kordofan region vs other Sub-Saharan areas, based on the traditional geographic provenance) were defined studying 44 GA samples with a non-targeted screening approach using high resolution mass spectrometry. From an initial group of 88 identified masses, 15 were selected to create a bi-factor PLS-DA statistical model able to correctly reclassify samples with 94.4% accuracy. Moreover, the study addressed the question of identifying gum addition in wines, analysing 98 untreated wines and comparing them with 40 wines to which gum arabic had been added (200 mg L−1). Considering the database of 88 masses, 4 of them were established to be markers of gum arabic addition (m/z 152.1067, 166.1225, 585.1428 and 643.1403). Principal component analysis performed with the signal (area) of the 4 masses highlighted three groupings differentiating untreated wines, wines treated with A. senegal gum and wines treated with A. seyal gum. m/z 152.1067 was tentatively identified as N-methyltyramine, while m/z 166.1225 as N,O-dimethyltyramine.