Polissacarídeos do epicarpo e do mesocarpo de café cereja, 2: Fracionamento e hidrólise ácida parcial da pectina solúvel em agua
The pectin isolated from the epicarp and the mesocarp of coffee cherries by extraction with ot 0.5 ammonium oxalate solution had about 73 of galacturonic acid, and neutral sugars galactose, arabinose, rhamnose, xylose, fucose and glucose. It was not possible to isolate a polygalacturonan free of neutral sugars by successive ethanolic precipitations and by chromatography on DEAE-cellulose (carbonate form). On partial acid hydrolysis, pectin yielded a mixture of neutral and acid oligosaccharydes. The acid oligosaccharydes identified by paper chromatography included the disaccharyde 4-0-(ÓGalactopyranosyluronic acid)-D-galacturonic acid and the aldobiuronic acids 2-0-(Ó-D-galactopyranosyluronic acid)-L-rhamnose, Ó-D-galactopyranosyluronic acid-arabinose, Ó-D-galactopyranosyluronic acid-arabinosa, Ó-D-galactopyranosyluronic acid-galactose, Ó-D-galactopyranosyluronic acid-xylose, Ó-D-galactopyraosyluronic acid-fucose and Ó-D-galactopyranosyluronic acid-glucose. These results suggest that neutral sugars are combined in the galacturonan chain molecule through glycosidic linkages, thus forming an acidic heteropolysaccharyde
| Main Authors: | , , |
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| Format: | biblioteca |
| Published: |
Jun
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| Subjects: | BIOQUIMICA, PECTINAS, POLISACARIDOS, ANALISIS DEL FRUTO, |
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| Summary: | The pectin isolated from the epicarp and the mesocarp of coffee cherries by extraction with ot 0.5 ammonium oxalate solution had about 73 of galacturonic acid, and neutral sugars galactose, arabinose, rhamnose, xylose, fucose and glucose. It was not possible to isolate a polygalacturonan free of neutral sugars by successive ethanolic precipitations and by chromatography on DEAE-cellulose (carbonate form). On partial acid hydrolysis, pectin yielded a mixture of neutral and acid oligosaccharydes. The acid oligosaccharydes identified by paper chromatography included the disaccharyde 4-0-(ÓGalactopyranosyluronic acid)-D-galacturonic acid and the aldobiuronic acids 2-0-(Ó-D-galactopyranosyluronic acid)-L-rhamnose, Ó-D-galactopyranosyluronic acid-arabinose, Ó-D-galactopyranosyluronic acid-arabinosa, Ó-D-galactopyranosyluronic acid-galactose, Ó-D-galactopyranosyluronic acid-xylose, Ó-D-galactopyraosyluronic acid-fucose and Ó-D-galactopyranosyluronic acid-glucose. These results suggest that neutral sugars are combined in the galacturonan chain molecule through glycosidic linkages, thus forming an acidic heteropolysaccharyde |
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