Degradative studies of gum arabic (Acacia Senegal (L.) Willd.) with special reference to the fate of the amino acids present

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Abstract
Solutions of gum arabic were subjected to (a) autohydrolysis at 98°C, (b) mild acid hydrolysis at 98°C, and (c) ultraviolet radiation. In each case, three products were isolated: an insoluble, highly proteinaceous precipitate; a degraded proteinaceous gum polysaccharide; and the mixture of mono‐ and disaccharides etc. plus amino acids/peptides recovered from dialysates of the treated solutions. Data are presented for the sugar and amino acid compositions of the nine products obtained. The results confirm the lability of some of the arabinose, rhamnose, and galactose, and establish that some amino acids in gum arabic are more labile than others. The degraded proteinaceous gum polysaccharides therefore become enriched in certain amino acids; there is a good correlation with the amino acids known, from sequential Smith‐degradations, to be enriched in the branched galactan core of the original gum macromolecules. The results of these studies are not only of structural interest; they are also of metabolic, immunological and food manufacturing interest because gum arabic solutions are invariably heated during industrial spray‐drying, sterilization, or food/beverage production operations to the detriment, hitherto poorly understood, of the original functionality of unprocessed gum arabic.