Pectin hairy regions

Figure 6. Gel filtration of apple pectin "hairy" regions after S-elimination on Sephaoryl S-300. (Reproduced with permission from reference 3. Copyright 1983 Carbohydrate Polymers).

Other polysaccharides of primary cell walls.-A complex mixture of enzymes including endopolygalacturonase, pectin methylesterase, and/or pectin lyase solubilizes a mixture of polysaccharides from the primary cell walls of fruits [57-64]. Food scientists have referred for some 15 years to this mixture of polysaccharides as the hairy region to describe the highly branched character of the polysaccharides in the fraction and to emphasize the contrast to unbranched homogalacturonan. The recent discovery of rhamnogalacturonan hydrolase [65,66], which selectively cleaves the backbone of RG-I, led to the realization that the hairy... 

Schols HA, Geraeds CCJM, Searle-van Leeuwen MF, Kormelink FJM, Voragen AGJ (1990a) Rhamnogalacturonase a novel enzyme that degrades the hairy regions of pectins. Carbohydr Res 206 105-115... 

Schols HA, Posthumus MA, Voragen AGJ (1990b) Structural features of hairy regions of pectins isolated from apple juice produced by the liquefaction process. Carbohydr Res 206 117-129... 

One peak is eluted at the void volume of the column and contained the bulk of neutral sugars and few galacturonic acid residues while the peak at the total volume contained almost pure oligogalacturonides. Therefore the same model of "hairy" regions and "smooth" regions also applied to these pectins. 

When comparing this result with that obtained with the acid-extracted pectins, the same two populations were separated but the amount of "hairy" regions is lower for the acid-extracted pectins (less than 10 % of the pectins) than for the pectins (=15 %). This result confirmed that extrusion-cooking is less degradative towards the side-chains that the acid treatment it also shows that both pectins have large "smooth" regions. 

Figure 1. Schematic representation of the structure of the smooth and hairy regions of pectin, including the various pectinases.

KP pectin from sugar beet pulp was from Kobenhavns Pectinfabrik (Lille Skensved, Denmark). G-pectin was extracted from the whole sugar beet by Grindsted Products, Denmark. A preparation of modified hairy regions (MHR) was isolated from apple [5]. The non pectic acetylated substrates are described elsewhere [6,7,8]. 

Colquhoun IJ, Ruiter GA de, Schols HA, Voragen AGJ (1990) IdentiHcation by n.m.r. spectroscopy of oligosaccharides obtained by treatment of the hairy regions of apple pectin with rhamnogalacturonase. Carbohydr Res 206 131-144... 

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