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University of Edinburgh (1987)

Studies on gum exudates with particular reference to gum arabic (Acacia senegal) and other Acacia species

McDougal, F.J.

Titre : Studies on gum exudates with particular reference to gum arabic (Acacia senegal) and other Acacia species.

Auteur : Mcdougal, Fiona Janet

Université de soutenance : University of Edinburgh

Grade : Doctor of Philosophy (Ph.D.) : 1987

Résumé partiel
Two commercial samples of gum arabic were characterised. The first, "gum arabic (old)", corresponded to analytical parameters for Acacia Senegal gum. The other, "gum arabic (new)", was suspected to contain 10% of Acacia seyal gum. A series of studies on laboratory rats were carried out involving gum arabic (new) . At a level of 15% of the diet, gum arabic was found to cause caecal enlargement within 72 hours, mainly due to an increase in the % moisture content of the caecum. Caecal enlargement was reversible, again within 72 hours. Heat-treated gum arabic caused a similar response. Treatment of rats, receiving 15% gum arabic, with Metronidazole had no discernible effect. An antibiotic cocktail of Eacitracin, Neomycin Sulphate and Streptomycin greatly affected the digestion of gum arabic. Caecal enlargement was greatly increased. This increase appeared due to remnants of gum arabic in the caecal contents. Some bacterial populations in the caecum were eliminated, volatile fatty acid (V.F.A.) concentrations also diminished, indicating that fermentation of gum arabic to V.F.A.’s in the caecum had been prevented. Solutions of gum arabic (new) were subjected to autohydrolysis, mild acidic hydrolysis and ultraviolet irradiation. In each case, three products were isolated :- an insoluble, highly proteinaceous precipitate ; a degraded proteinaceous gum polysaccharide ; and a diffusate. 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.

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