To evaluate the fermentation properties of oligosaccharides derived from pectins and their parent polysaccharides, a 5-ml-working-volume, pH-and temperature-controlled fermentor was tested. Six pectic oligosaccharides representing specific substructures found within pectins were prepared. These consisted of oligogalacturonides (average degrees of polymerization [DP] of 5 and 9), methylated oligogalacturonides (average DP of 5), oligorhamnogalacturonides (average DP of 10 as a disaccharide unit of galacturonic acid and rhamnose), oligogalactosides (average DP of 5), and oligoarabinosides (average DP of 6). The influence of these carbohydrates on the human fecal microbiota was evaluated. Use of neutral sugar fractions resulted in an increase in Bifidobacterium populations and gave higher organic acid yields. The Bacteroides-Prevotella group significantly increased on all oligosaccharides except oligogalacturonides with an average DP of 5. The most selective substrates for bifidobacteria were arabinan, galactan, oligoarabinosides, and oligogalactosides.Pectins are complex plant heteropolysaccharides consisting in the main of four types of carbohydrate structure. These are partially methyl and/or acetyl esterified polygalacturonic acid (PGalA), rhamnogalacturonan type I (RG I), xylogalacturonan, and rhamnogalacturonan type II (RG II). PGalA is a linear homopolymer of ␣-(1,4)-galacturonic acid. Xylogalacturonan consists of a PGalA backbone with xylose bound to galactopyranosyluronic acid (GalpA) at C-3. RG I and RG II comprise the so-called "hairy regions" due to their branched structures. The -4-␣-D-GalAp-1,2-␣-L-Rhap-1-disaccharide sequence constitutes the main chain of RG I, with substitutions at position 4 of the rhamnose residues as well as acetylation on C-2 or C-3 of the galacturonic acid. Side chains are ␣-(1,5)-arabinan, ␤-(1,4)-galactan, and arabinogalactan type I. RG II is very complex, but it is believed to be the most conserved part of pectin. This molecule has PGalA as a backbone and is branched with rhamnose and other rare sugars such as apiose, 2-O-methylxylose, and 2-O-methylfucose (31).The biological effects of pectins have been studied extensively, and they are reported to be highly fermentable dietary fibers (5). Apart from their complexity and heterogeneity, both pectins and their derivatives have been investigated for many other potential health benefits. Pectins are found in oriental medicinal herbs and are thought to be responsible for their therapeutic effects (18,27). Studies to date indicate that different regions of pectins may mediate the different health effects. For example, modified citrus pectin may control the progress of malignancy (12) or induce apoptosis in cancer cell lines (20,29). In terms of the selectivity of fermentation by fecal bacteria, pectic oligosaccharides had greater selectivity toward bifidobacteria in batch cultures than the parent pectin (24,25,30).Many plant by-products are rich in pectins, which could possibly be sources of active pectic compounds and may prove ...

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Pectins are complex branched polysaccharides present in primary cell walls. As a distinctive feature, they contain high amount of partly methyl-esterified galacturonic acid and low amount of rhamnose and carry arabinose and galactose as major neutral sugars. Due to their structural complexity, they are modifiable by many different enzymes, including hydrolases, lyases, and esterases. Their peculiar structure is the origin of their physicochemical properties. Among others, their remarkable gelling properties make them a key additive for food industries. Pectin-degrading enzymes and -modifying enzymes may be used in a wide variety of applications to modulate pectin properties or produce pectin derivatives and oligosaccharides with functional as well as nutritional interests. This paper reviews the scientific information available on pectin structure, pectin-modifying enzymes, and the use of enzymes to produce pectin with controlled structure or pectin-derived oligosaccharides, with functional or nutritional interesting properties.

A monoclonal antibody (LM8) was generated with specificity for xyloglacturonan (XGA) isolated from pea (Pisum sativum L.) testae. Characterization of the LM8 epitope indicates that it is a region of XGA that is highly substituted with xylose. Immunocytochemical analysis indicates that this epitope is restricted to loosely attached inner parenchyma cells at the inner face of the pea testa and does not occur in other cells of the testa. Elsewhere in the pea seedling, the LM8 epitope was found only in association with root cap cell development at the root apex. Furthermore, the LM8 epitope is specifically associated with root cap cells in a range of angiosperm species. In embryogenic carrot suspension cell cultures the epitope is abundant at the surface of cell walls of loosely attached cells in both induced and non-induced cultures. The LM8 epitope is the first cell wall epitope to be identified that is specifically associated with a plant cell separation process that results in complete cell detachment.

Cellulose microfibrils, lignins and annulus-restricted pectins have different physicochemical properties (rigidity, hydrophobicity, porosity) that have different effects on the hydraulic functions of the PM, and these influence both the hydraulic efficiency and vulnerability to cavitation of the pits, including ion-mediated control of hydraulic conductance. Impregnation of the cellulose microfibrils of the PM with lignins, which have low wettability, may result in lower cavitation pressure for a given pore size and thus help to explain the vulnerability of this species to cavitation.