P.C. Bell

Composition of gum exudates from Anacardium occidentale

Abstract The composition and solution properties of Indian and Papuan specimens of the gum from Anacardium occidentale have been studied and found to be closely similar. Contrary to earlier reports by Indian workers, this gum does not contain galacturonic acid. It does, however, contain glucose; this appears to be the first report of the presence of this sugar in a plant gum exudate. A freeze-dried sample of the gum was examined at intervals over a period of 2 months; its weight-average MW increased by a factor of three in that time, and molecular-sieve chromatography showed that self-association occurred with the formation of a small proportion of a very high MW component.

Analysis of six Acacia gum exudates of the series phyllodineae

Abstract Gum specimens from Acacia calamifolia, A. difformis, A. falcata, A. mabellae, A. retinodes, and A. rubida have been analysed; the first named belongs to Benthams Series 1, subseries 4C (Calamiformes Uninerves) and the others are in Benthams Series 1, subseries 6F (Uninerves Racemosae). This group of gum exudates, of which A. rubida is the most divergent, is characterized by a low rhamnose content (>2%), low acidity, low intrinsic viscosity, and a high galactose/arabinose ratio, which, for A. calamifolia and A. falcata, is higher than for any other species studied so far. Although these gum species have good solubility, their solutions are of low viscosity and are dark in colour; they are unlikely to be of commercial importance. In the light of the chemical data now available for Acacia gum exudates, A. cyanophylla appears to be a highly anomalous species within the Phyllodineae.

The composition of the gum exudates from some combretum species; the botanical nomenclature and systematics of the combretaceae

Abstract An analytical study has been made of gum specimens from Combretum collinum , C. collinum subsp. hypopilinum , C. erythrophyllum , C. nigricans , C. fragrans , and C. glutinosum . In comparison with the genus Acacia , both the botanical classification and synonymy, and the chemistry, are more complex. Glucuronic acid, galacturonic acid, 4- O -methylglucuronic acid, galactose, arabinose, and rhamnose are present in all the specimens studied. In addition, mannose and xylose are present in the gum from C. collinum , which is therefore similar to C. hartmannianum . The data now available suggest that, as a group, the genus Combretum produces gum exudates that are more viscous, of higher molecular weight, and more acidic than those of the Acacia group.

An analytical study of some Acacia gum exudates of the series Botryocephalae

An analytical study has been made of gum specimens from Acacia deanei, A. filicifolia (three specimens), A. leucoclada, A. parramattensis (two specimens), A. parvipinnula, A. silvestris, A. terminalis, and A. trachyphloia, which are species belonging to Series II ({Botryocephalae}) in Benthams classification of the genus. The three specimens from A. filicifolia are all closely similar, but the specimens from A. parramattensis differ appreciably in parameters other than their sugar ratios. Several of the analytical values reported increase considerably the range of values established so far for Acacia gum exudates. The Botryocephalae species give gum exudates of at least 2 chemically distinct types. Group A species (A. deanei, A. parramattensis, A. parvipinnula, and {A. trachyphloia}) have low galactose-arabinose ratios ( 41) but low negative or positive rotations, low intrinsic viscosities and molecular weights, and relatively low nitrogen, methoxyl, uronic anhydride, and rhamnose contents.

The gum exudates from Chloroxylon swietenia, Sclerocarya caffra, Azadirachta indica and Moringa oleifera☆

Abstract Analytical data are presented for the polysaccharide and proteinaceous components of the gum exudates from Chloroxylon swietenia and Sclerocarya caffra, and for the amino acid compositions of the exudates from Azadirachta indica (two specimens) and Moringa oleifera. The gums from C. swietenia and S. caffra contain 4-O-methylglucuronic acid, glucuronic acid, galactose and arabinose; rhamnose is absent. Amino acid analysis shows that proteinaceous material is present in the gums from C. swietenia, S. caffra and M. oleifera despite their low nitrogen content. Hydroxyproline accounts for 28 % of the amino acid content of S. caffra gum. In contrast, A. indica gum has a high nitrogen content but contains very little hydroxyproline.

The identification of combretum gum exudates which are not permitted food additives

Gum exudates from the genus Combretum may be used commercially for technological applications, but are not included on any of the regulatory lists of permitted food additives. Analytical data permitting their identification are therefore required to allow food law compliance to be monitored. This paper presents data, e.g. polysaccharide and amino acid compositions, nitrogen conversion factors, and some physico‐chemical parameters which characterize the gum exudates from eight Combretum species. Some ways in which the current specification of identity and purity for gum arabic (Acacia Senegal (L.) Willd.) could be amended to preclude its adulteration with Combretum gums are suggested.

The composition and properties of gum exudates from subspecies of Acacia tortilis

Abstract Gum specimens from Acacia tortilis ssp. spirocarpa, ssp. raddiana var. pubescens (two specimens) and ssp. heteracantha (three specimens) have been analysed. The results are of chemotaxonomic interest. Although the gum from ssp. raddiana var. pubescens appears to be intermediate between those from ssp. spirocarpa and ssp. heteracantha in terms of some of the analytical parameters, the overall impression is that ssp. raddiana is more similar chemically to ssp. spirocarpa than to ssp. heterocantha. The latter yields a viscous, proteinaceous polysaccharide that differs from those from both ssp. spirocarpa and ssp. raddiana by having a much higher ratio of arabinose to galactose, higher nitrogen and methoxyl contents, and much higher intrinsic viscosity and molecular weight; preliminary experiments have shown this gum to consist of two components.

The gum exudates from acacia dealbata and acacia sieberana: corrections to previous analytical data

Abstract In the light of the analytical data acquired for the gum exudates from a greatly increased number of Acacia species in recent years, the data published for A . sieberana gum in 1939, and for A . dealbata gum in 1966, differ considerably, in several respects, from the range of values established for some closely related species. Seven specimens of gum from A. dealbata and four specimens from A. sieberana have therefore been studied; from the analytical results, it must be concluded that much of the data published earlier for A. dealbata and A. sieberana cannot be regarded as typical of these species.

The composition and properties of the gum exudates from Terminalia sericea and T. Superba

Abstract The gum polysaccharides from Terminalia sericea and T. superba have been analysed. They have a complex sugar composition, containing galacturonic, glucuronic, and 4-O-methylglucuronic acids as well as galactose, arabinose, rhamnose, mannose and xylose. The exudates from T. sericea and T. superba are remarkably similar in composition, particularly with respect to their proportions of neutral sugars and total uronic acid content, although T. sericea gum contains considerably more 4-O-methylglucuronic acid than T. superba. Both gums are very viscous and dissolve readily to give solutions of good colour.!!

The gum exudates from Brachystegia and Julbernardia species

Abstract Analytical data are presented for the water-soluble gum exudates from Brachystegia glaucescens, B. spiciformis , and Julbernardia globiflora . They are acidic polysaccharides containing glucuronic acid, 4- O -methylglucuronic acid and galacturonic acid, together with galactose, minor amounts of arabinose, and relatively high proportions of rhamnose. The exudate from B. glaucescens is of particular interest in having high molecular weight, high intrinsic viscosity, and a high methoxyl content. The nitrogen content of all three gums is low, but amino acid analysis shows that proteinaceous components are involved, as in the gum exudates from other genera.