Cells wall material

Historically, dietary fiber referred to iasoluble plant cell wall material, primarily polysaccharides, not digested by the endogenous enzymes of the human digestive tract. This definition has been extended to iaclude other nondigestible polysaccharides, from plants and other sources, that are iacorporated iato processed foods. Cellulose [9004-34-6] (qv) is fibrous however, lignin [9005-53-2] (qv) and many other polysaccharides ia food do not have fiberlike stmctures (see also Carbohydrates). 

Detergent Methods. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) methods (2), later modified for human foods (13), measure total insoluble plant cell wall material (NDF) and the cellulose—lignin complex (ADF). The easily solubilized pectins and some associated polysaccharides, galactomaimans of legume seeds, various plant gums, and seaweed polysaccharides are extracted away from the NDF. They caimot be recovered easily from the extract, and therefore the soluble fiber fraction is lost. 

Protoplast ciAture.s. Cellular tissues devoid of cell wall material in culture... 

Cellular materials can collapse by another mechanism. If the cell-wall material is plastic (as many polymers are) then the foam as a whole shows plastic behaviour. The stress-strain curve still looks like Fig. 25.9, but now the plateau is caused by plastic collapse. Plastic collapse occurs when the moment exerted on the cell walls exceeds its fully plastic moment, creating plastic hinges as shown in Fig. 25.12. Then the collapse stress (7 1 of the foam is related to the yield strength Gy of the wall by... 

This apparent time dependent cell disruption is caused because of the statistically random distribution of the orientation of the cells within a flow field and the random changes in that distribution as a function of time, the latter is caused as the cells spin in the flow field in response to the forces that act on them. In the present discussion this is referred to as apparent time dependency in order to distinguish it from true time-dependent disruption arising from anelastic behaviour of the cell walls. Anelastic behaviour, or time-dependent elasticity, is thought to arise from a restructuring of the fabric of the cell wall material at a molecular level. Anelasticity is stress induced and requires energy which is dissipated as heat, and if it is excessive it can weaken the structure and cause its breakage. 

A red wine was obtained from Carignan noir grapes Vitis vinifera) harvested in 1991 at the INRA-Pech Rouge Experimental Station. Mature grapes were stemmed and crushed before fermentation (7 days at 28 °C) in presence of total grape berry cell wall material. The insoluble material was finally eliminated by pressing, 5 g/hL SO2 was added and the obtained red wine stored at 12°C. 

Diisterhoft E-M, Bonte AW, Venekamp JC, Voragen AGJ (1993) The role of fungal polysaccharidases in the hydrolysis of cell wall materials from sunflower and palm-kemel meals. World J Microbiol Biotechnol 9 544-554... 

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. 

The same methods (chemicals, enzymes, physical treatments) can be also applied on the cell wall materials not with the aim of extracting polysaccharides but with the aim of obtaining modified fibres. New properties concerning for exemple fermentability, ratio soluble/insoluble dietary fibre, hydration., can be obtained (1). 

Soy cell wall material (Soy CWM) was isolated by Alcalase treatment and jet cooking (115°C, 4 minutes) of soy meal followed by centrifugation and recovery of insolubles. Aliqots of 1% suspensions of soy CWM in O.IM acetate buffer pH 5.0 were incubated with enzymes (40pg of each to 1.5 ml of substrate) at 30°C for 24 hours and the solubilized material was analyzed by HPSEC and HPAEC. 

The solubilisation of soy cell wall material (CWM) by the two rhamnogalacturonases (RGase A and RGase B) in combination with other pectinolytic enzymes were compared in order to identify enzymes for new soy processes or products. The experiments were carried out at pH 5.0, where both rhamnogalacturonases have about 25% of their maximum activity, and with high enzyme dosages to ensure that the maximum effects are obtained. 

Pectins from different tissue zones, namely epidermis, the outer parenchyma, the parenchyma of the Ccirpels zone, the carpels and the core line, were isolated firom alcohol-insoluble solids (AIS. In both zones of parenchyma, the cell-wall material represented about 80% of the total cell-wall material from the whole fruit. The pectins from the outer parenchyma accounted for 70% of the total. However, there was no change in galacturonic acid concentration. The enzymatic solubilisation of tissues or AIS was higher in the parenchyma zones than in the others. Nevertheless, the depolymerisation of the soluble pectins from parenchyma zones with an endopolygacturonase required the action of pectin methylesterase. The depoiymerisation of pectins from the other zones, however, did not. 

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. 

The outer parenchyma (B) is the major tissue zone of the fruit, corresponding to more than 80 % of dry matter and the edible zones (B and C) contained 80 % of the cell-wall material (Fig.2). 

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. 

Sulfur compounds such as furfuryl mercaptans have a rotten odor but in small amounts are coffee-like.15 Furfuryl mercaptan itself has an odor threshold of 0.005 ppb in water but at 10 ppb in water it imparts a distinctly stale odor.19 The particular precursors of furfuryl mercaptan seem to be the coffee cell wall material which contains both arabinogalactan as a pentose sugar source and protein such as glutathione.84 Other sulfur compounds such as kahweofuran and methyldithiofurans impart a meaty odor if their concentrations are high enough.19... 

This polysaccharide is the cell-wall material of siphoneous green algae. The unit cell is hexagonal, with a = c = 15.4 A (1.54 nm),... 

Codium cell-walls contain no crystalline mannan unless they are treated with boiling water. An orthorhombic unit-cell with a = 7.21 A (721 pm), b(fiber axis) = 10.27 A (1.027 nm), and c = 8.82 A (882 pm) was derived. Cell-wall material treated with 12-14% potassium hydroxide gave a different diagram, corresponding to mannan II. In a water-saturated atmosphere, the unit cell for mannan II is monoclinic, with a = 18.8 A (1.88 nm), fo(fiber axis) = 10.2 A (1.02 nm), c = 18.7 A (1.87 nm), and R = 57.5°. 

Fluorescence occurs when radiant energy is absorbed and then, almost instantly, some of the energy is re-emitted, usually at a longer wavelength. Primary fluorescence (autofluorescence) occurs in flavo-proteins (13), plant cell wall materials such as lignin (7), and in flagella (14). Secondary fluorescence is when a material binds a fluorescent dye... 

Protein content of field peas is negatively correlated with lipid, cell wall material (CWM), sugar, and ash content and positively correlated with starch separation efficiency and protein separation efficiency in air classification of pea flour. The lower separation efficiency of low protein peas may be due to their high lipid and CWM content which makes disintegration of seeds and separation into protein and starch particles by pin milling difficult. It is suggested that peas with a specific protein content should be used in order to control the protein and starch fraction contents (18). 

Grain legumes have also been processed into refined starch (10,11) and protein isolates (12,13,14) by procedures derived from the traditional corn starch and soybean protein industries (15). However, comparative data on product yields, composition and losses have not been published. A commercial plant for the wet processing of field pea into refined starch, protein isolate and refined fiber has been established in Western Canada. Little is known about the characteristics of the protein isolate or refined fiber product. Water-washed starch prepared from the air-classified starch fractions of field pea (16,17) and fababean (6) have been investigated for certain physico-chemical and pasting properties. Reichert (18) isolated the cell wall material from soaked field pea cotyledons and determined its fiber composition and water absorption capacity. In addition, the effects of drying techniques on the characteristics of pea protein Isolates have been determined (14). 

Ubiquitous in seeds is phytic acid, the hexaphosphate ester of inositol, which has been isolated from cucurbit seeds (57). Small amounts of free sugars and terpenoid glycosides (cucurbitacins) are also present (58-60), but starch is absent (1, 1). Cellulosic cell wall materials comprise the remaining carbohydrate content. 

Figure 2.11 The change in volumetric swelling behaviour due to (a) loss of cell wall material but not cell wall bulking agent, and (b) loss of cell wall cross-linking agent.

Selvendran and coworkers hydrolyzed plant cell-wall materials by using 2 M CF3CO2H for 2 h at 120°, and M sulfuric acid for 1, 2, 5, and 8 h at 100° with (Saeman hydrolysis), or without, a prior 72% H2SO4 step for... 

---