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Polímeros

versão impressa ISSN 0104-1428

Resumo

SILVA, André G. da; RODRIGUES, Judith F.  e  PAULA, Regina Célia M. de. Composition and rheological properties of exudate gum from anadenanthera macrocarpa. Polímeros [online]. 1998, vol.8, n.2, pp.34-40. ISSN 0104-1428.  https://doi.org/10.1590/S0104-14281998000200006.

A pure salt gum was obtained by using a method of purification based on dissolutions in water and precipitation with ethanol, first in presence of NaCl, and later in absence of salt. Characterization was performed by determination of moisture, ash, protein and cations. The composition of the polysaccharide was determined as 67.8% arabinose, 24.1% galactose, 2.0% rhamnose by HPLC and 5.9 % of uronic acid by condutometric analysis. Cations presents in the crude gum (Na+, K+, Ca2+, Mg2+ and Fe3+) were investigated by atomic absorption spectrophotometry and gradually substituted by Na+. Protein was tightly bounded to the polysaccharide. GPC suggested the presence of polysaccharide-protein complex of molar mass ca 7.9 x 105 g/mol, and polysaccharides of molar masses of 8.3 x 104 g/mol and 2.2 x 104 g/mol. The whole gum has low viscosity and an activation energy of flow of 16,8 kJ/mol, 17,2 kJ/mol and 17,7 kJ/mol for solution at 2, 3 and 5%, respectively. Comparison with other polysaccharides indicated that angico gum is a branched macromolecule, but in small amount than arabic gum and cashew nut tree gum.

Palavras-chave : Gum exudate; polysaccharide; Anadenanthera Macrocarpa; rheology.

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