A polysaccharide that yields galacturonic acid on hydrolysis; a constituent of some pectins.
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The aim of German scientists and colleagues was to investigate both water-binding and gelling properties of two orange fiber preparations from pulp and peel with a galacturonan polysaccharide content of greater than 27% and a degree of methoxylation greater than 65%.
Table 2: Effect of drying methods on the galacturonan acid contents of water extractable pectin (WEP), CDTA extractable pectin (CEP), and [Na.sub.2]C[O.sub.3] extractable soluble pectin (NEP) of the apple chips obtained by different drying methods.
Polymer Carbon Chemical Shifts (in ppm) Galacturonan C-6 free 172.8 Galacturonan C-6 ester 171.0 Arabinan C-1 -- Galacturonan C-1 100.5 Arabinan C-4 84.5 Arabinan C-4 83.0 Arabinan C-2 81.0 Galacturonan C-4 79.1 Galactan C-4 77.1 Arabinan C-3 76.8 Galacturonan C-3 71.6 Galacturonan C-5 73.8 Galacturonan C-2 68.3 Arabinan C-5 67.0 Galactan C-6 61.6 Arabinan C-5 61.0 Galacturonan OC (H) 3 53.5 "--": not detected.
Polygalacturonase (PG) acts on the pectin chain by adding a water molecule to break the linkage between two galacturonan molecules; Pectin lyase (PL) acts on the galacturonan chain by removing a water molecule from the linkage to break it and to release its products; whereas, Pectin esterase esterifies the pectin by removing methoxy esters (3).
and Marat, K., 'NMR Characterization of a 4-O-methyl-D-glucuronic Acid Containing rhamno- galacturonan from Yellow Mustard (Sinapis alba L.) Mucilage', Carbohydr.
When the galacturonan moiety of pectic polysaccharides in F-5 was degraded enzymatically by endo-polygalacturonase, the digestion products significantly increased the activity of F-5.
The backbones of these regions fall into two groups: those containing 1,4-linked [alpha]-D-GalpA residues (galacturonans) and those made up of a repeating disaccharide unit [[[right arrow] 2)- [alpha]-L-Rha_p-(1 [right arrow] 4)- [alpha]-D-GalpA- (1 [right arrow]].sub.n] (RG-I).