Apples cell wall materials

Le Bourvellec, C., Guyot, S., Renard, C. M. G. C. (2004). Non-covalent interaction between procyanidins and apple cell wall material. Part I - Effect of some environmental parameters. Biochim. Biophys. Acta, 1672, 192-202. 

C. Le Bourvelleca, B. Bouchetb, and C.M.G.C. Renard, "Non-covalent interaction between procyanidins and apple cell wall material. Part III Study on model polysaccharides", Biochimica et Biophysica Acta, Vol. 1725, pp. 10-18,2005. 

Renard, C. M. G. C., Schols, H. A., Voragen, A. G. J., Thibault, J.-F. and Pilnik, W. (1991b). Studies on apple protopectin. III. Characterization of the material extracted by pure polysaccharidases from apple cell walls. Carbohydr Polymers 15, 13-32. 

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. 

In apple processing, enzymatic treatment of the crushed fruit leads to a lower degree of degradation of the peel and the core than the rest of the fruit. Figure 1 shows the separate tissue zones in diagrammatic form. Their anatomic origins are different the epidermis and outer parenchyma zones are tissues derived from the fusion of the calyx, corolla and stamens of the flower the inner zones correspond to tissue derived from ovaries and carpels. The characterisation of the cell-wall material, especially pectins, from the different zones of the fruit may provide additional information on the possibility of finding uses for the discarded fractions. 

When the apple tissues were treated with enzyme preparation for liquefaction (Fig. 3), the cell-wall materials were solubilised with different yields, 95, 86, 66 and 59 % for zones B, C, D and A, respectively. The sequence was the same with the maceration treatment (use of polygalacturonase [PG] only) but the yields were lower. 

Apple cultivars have different textures due to their internal variability of structure and composition. Some apples resist boiling and do not readily sauce. Others may undergo ready cell separation. This wide range of textural behavior illustrates the complexity due to pectins and other cell-wall materials. Select apple cultivars according to the desired processing qualities. 

Ascorbate oxidase is mostly found in the peripheral part of the plant, as shown in Figure 1 for cauliflower and apple that had been cut through the middle and pressed on a piece of paper coated with a solution of L-ascorbate and the redox dye dichloroindophenol (14). The close association with the cell-wall material gives some support to the theory that the enzyme might be important for plant growth and ripening of... 

In our studies on the polysaccharide constituents of carrots and apples the following considerations have been borne in mind (i) that account must be taken of the readily soluble as well as of the more obviously fibrous non-starchy polysaccharides (11) that cell wall materials must be prepared with minimum loss of these more readily soluble polysaccharides (ill) Chat broad spectrum analyses of pectlc substances and hemlcelluloses, even when supported by determinations of Individual sugar components, are rarely sufficient to establish the nature of these substances since the same sugar constituents occur In quite... 

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. 

Extrusion-cooking increased very significantly the water-solubility of plant cell wall rich-materials. High amounts of pectins can be solubilised from sugar-beet pulp, citrus peels or apple pomace. 

Genuit W, Boon JJ (1985) Pyrolysis-gas chromatography-photoionization mass spectrometry a new approach in the analysis of macromolecular materials J Anal Appl Pyrolysis 8 25-40 Genuit W, Boon JJ, Falx O (1987) Characterization of beech milled wood lignin by pyrolysis-gas chromatography photoionization mass spectrometry Anal Chem 59 508-512 Hartley RD Haverkamp J (1984) Pyrolysis mass spectrometry of the phenolic constituents of plant cell walls J Sci Food Agnc 35 14-20... 

Other organic fiber products which are mostly used in foods as dietary ballast additives are made from wheat, oats, tomato, apples, and citrus. Such dietary fibers are non-starch polysaccharides obtained from cell walls only, which can not be broken down by the digestive enzymes of the human organism and, therefore, constitute inert ballast materials. Color, taste, and odor relate to the fiber source. Unlike cereal brans or dietary fibers derived from, for example, sugar beets, which are often rejected by consumers because of their specific taste, wheat, oat, tomato, apple, and citrus fibers offer physiological properties that are much more readily accepted. 

In general, there is some evidence to support a 5—8% reduction (approximately 0.5 mmol/L) in total cholesterol after the intake of three apples per day. Moreover, apple juice consumption is associated with no effects or increased levels of TAG. Clear apple juice lacks water-soluble pectin and has a low polyphenol content due to a clarification process. The production of cloudy apple juice does not include clarification and, thus, may maintain an important polyphenol and pectin content.Apple pomace, a by-product of juice production, consists of approximately 25% of fresh apple weight, and is a high source of fiber and polyphenols and therefore a valuable material for functional food products. Apart from the pol3q>henol and fiber content, food matrix may also play an important role whole apples contain intact cell wall components, which could contribute to the effects on lipid and glucose metabolism as will be described below. 

Pectins are polysaccharides that occur in all plants, primarily in the cell wall, in low amounts of 1-5%. They are, however, particularly prevalent in fruits, where the amounts are much higher. For example, apple pulp contains 10-15% (w/w) pectin, and orange and lemon rinds contain 20-30% (w/w). Pectins act as an intercellular cementing material that gives body to fruits and helps them keep their shape. When fruit becomes overripe, the pectin is broken down into its constituent monosaccharide sugars. As a result, the fruit becomes soft and loses it firmness. 

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