Apples polysaccharides

The results of sugar analyses of the CWM and AIR (Table VI) from parallel batches of apples likewise indicate similar overall carbohydrate compositions with only small losses of pectlc substances from the CWM, a conclusion again supported by the isolation of smaller quantities of these materials on subsequent extraction. Structural studies on apple polysaccharides will be reported elsewhere. 

Pectin. Pectin [9000-69-5] is a generic term for a group of polysaccharides, mainly partially methoxylated polygalacturonic acids, which are located in the cell walls of all plant tissues. The main commercial sources of pectin are citms peel and apple pomace, where it represents 20—40% and 10—20% of the dry weight respectively. The pectin is extracted, the extract purified, and the pectin precipitated (50) increased extraction times lead to the production of low methoxyl pectins. 

Pectin is a long chain of pectic acid and pectinic acid molecules. Because these acids are sugars, pectin is categorized as a polysaccharide. It is prepared from citrus peels and the remains of apples after they are squeezed for juice. In the plant, pectin is the material that joins the plant cells together. When fungus enzymes break down the pectin in fruit, the fruit gets soft and mushy. 

IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Symbols for specifying the conformation of polysaccharide chains (Recommendations 1981), Eur. J. Biochem, 131, 5-7, (1983) Pure Appl. Chem., 55,1269-1272 (1983) ref. 2, pp. 177-179. 

The rheological behavior of storage XGs was characterized by steady and dynamic shear rheometry [104,266]. Tamarind seed XG [266] showed a marked dependence of zero-shear viscosity on concentration in the semi-dilute region, which was similar to that of other stiff neutral polysaccharides, and ascribed to hyper-entanglements. In a later paper [292], the flow properties of XGs from different plant species, namely, suspension-cultured tobacco cells, apple pomace, and tamarind seed, were compared. The three XGs differed in composition and structural features (as mentioned in the former section) and... 

Arabinogalactans (AGs) are widely spread throughout the plant kingdom. Many edible and inedible plants are rich sources of these polysaccharides. AGs occur in two structurally different forms described as type I and type II, associated with the pectin cell-wall component by physical bonds and some of them are covalently linked to the complex pectin molecule as neutral side chains. Commercial pectins always contain AG 10-15%). AG of type I has a linear (1 4)-y0-o-Galp backbone, bearing 20-40% of of-L-Ara/ residues (1 5)-linked in short chains, in general at position 3. It is commonly found in pectins from citrus, apple and potato [6]. Recently, this AG type has been isolated from the skin of Opuntia ficus indica pear fruits [372]. 

Total polysaccharides were recovered in the ultrafiltration retentates on a Carbosep M5 membrane (Tech-Sep, MWCO 20 kDa) in the case of the red wine, or on a Centricon 30 membrane (Amicon, MWCO 30 kDa) in the ease of the apple and tomato juices. RG-II purification from the total polysaccharide coneentrates included, if necessary, several chromatography steps ... 

The total polysaccharide preparations from wine, apple and tomato juices were analysed in our HPSEC system. The obtained profiles (Figure 2) were all characterized by the presence of a main sharp peak eluted at the same elution volume (18.2 to 18.6 min) as a previously purified wine RG-II [20]. 

Extrusion-cooking of cell-wall rich products (e.g. wheat bran, apple pomace, citrus peels, sugar-beet pulp, pea hulls.) led to an important solubilisation of polysaccharides of various types without extensive degradation of the polymeric structure. The possibility of obtaining gelled systems directly with the extruded pectin-rich materials was demonstrated. 

Many plant products are very rich in cell wall materials. Cereal brans, seed hulls, various pulps (including beet pulp), citrus peels, apple pomace... are typical exemples of such by-products (1,2). They can be used after simple treatments as dietary fibres, functional fibres or bulking agents, depending on the nutritional claims (2). They can be used also eis sources of some polysaccharides. 

Monosaccharides composition of pectic polysaccharides in different tissue zones of apple... 

To date, the structural features of pectic polysaccharides and plant cell walls have been studied extensively using chemical analysis and enzymatic degradation. In addition, research on isolation and physicochemical characterisation of pectin from citrus peels, apple peels, sunflower head residues and sugar beet pulp has been reported (2). However, the pectic polysaccharides extracted from wheat straw have only previously been reported by Przeszlakowska (3). The author extracted 0.44% pectic substances from Author to whom correspondence should be addressed. 

Yu, L.P. and Rollings, J. E., Quantitative branching of linear and branched polysaccharide mixtures by size exclusion chromatography and on-line low-angle laser light-scattering detection, /. Appl. Polym. Sci., 35, 1085, 1988. 

Rees, D. A., Polysaccharide shapes and their interactions — some recent advances, Pure Appl. Chem., 53, 1, 1981. 

Pectin is used in foods in two forms, high methoxyl pectin and low methoxyl pectin. High methoxyl pectin is the form normally found in fruit while low methoxyl pectin is a chemically modified pectin. Pectins are acidic polysaccharides that occur in the cell walls of fruit. The commercial source of pectin is either citrus peel or apple pomace. The citrus peel is the residue from the production of citrus juices while apple pomace is the residue of cider production. Thus pectin is a by-product of either cider or fruit juice production. 

Lenart, A. and Dabrowska, R. 1997. Osmotic dehydration of apples with polysaccharide coatings. 

Polysaccharide-protein interaction has also been reported in apple juice, between arabinogalactan and protein (Brillouet et al., 1996). 

Nitric acid is less commonly used for hydrolysis, but, in combination with urea, has been recommended for polysaccharides containing uronic acid residues28 and it has been used in a study of apple pectin.29... 

Kenis PR (1971) Turbulent flow friction reduction effectiveness and hydrodynamic degradation of polysaccharides and synthetic polymers J Appl Polym Sci 15 607... 

Atkinson, R.G., Schroder, R., Hallett, I.C., Cohen, D., and MacRae, E.A. 2002. Overexpression of polygalacturonase in transgenic apple trees leads to a range of novel phenotypes involving changes in cell adhesion. Plant Physiol. 129 122-133. Bach, E. and Schollmeyer, E. 1992. An ultraviolet-spectrophotometric method with 2-cyano-acetamide for the determination of the enzymatic degradation of reducing polysaccharides. Anal. Biochem. 203 335-339. 

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