Cellulose pentosans

Dried, ripe coriander fruit contain steam-volatile oil, fixed (fatty) oil, proteins, cellulose, pentosans, tannins, calcium oxalate and minerals. The major constituents are fibre (23-36%), carbohydrates (about 20%), fatty oil (16-28%) and proteins (11-17%). The residues remaining after distillation of the essential oil contain high fat and protein, which is useful as animal feed. 

Pulp NaOU added Ter., YieU, % Alpha cellulose, % Pentosan, %... 

O) B n p>. Country Holocellulose Alpha Cellulose Other Cellulose Pentosans Klason Lignin Ash ... 

Clark and Wolff carried out the first studies on the changes in the chemical composition of kenaf as a function of the growing season [22]. They also studied the chemical differences along the stem and between leaves and stem. This data showed that the pentosans, lignin, and a-cellulose content increases with age, while the protein and hot water extractives content decreases with age. Data taken from the top part of the plant shows similar trends however, the top part has less cellulose, pentosans, and lignin, but higher hot water extractives and protein than the bottom part of the plant (Table 7.4). 

Ash Cmde protein (N X 6.25) Lipids Cmde fibei Cellulose Pentosans Starch... 

The pentosan polysaccharides, xylan and arabinan, commonly known as hemiceUulose, are the principal precursors of furfural and are always found together with lignin and cellulose in plant materials. 

The support for a chemical linkage between cellulose and lignin in wood, presented by Hibbert and co-workers (90), is based on their treatment of oak wood with acetic anhydride, glacial acetic acid and catalytic amounts of sulfuric acid. A fraction soluble in dioxane was found to have, after several precipitations, the same composition of lignin, cellulose and pentosan as that of the wood itself. 

A great deal of work is reported in the literature concerning the formation of lignin directly from cellulose or pentosans. Phillips (92), (93), on the basis of his work on annual plants, opposed this theory. According to him, lignin is produced in the plant directly from glucose or sucrose. 

Xylan occurs in practically all land plants and is said to be present in some marine algae.6 In both wide botanical distribution and abundance in nature it closely follows cellulose and starch. It is most abundant in annual crops, particularly in agricultural residues such as corn cobs, corn stalks, grain hulls and stems. Here it occurs in amounts ranging from 15 to 30%. Hard woods contain 20 to 25% xylan while soft woods contain 7 to 12 %. Spring wood has more pentosan than summer wood. 7 Low strength vegetable fibers of commerce such as jute, sisal, Manila... 

Usually it is considered that xylan has been effectively removed if the extracted residue compares in composition to a-cellulose. Yet, even a-cellulose contains small amounts of xylan as well as other hemicelluloses such as mannan.67 69 Beta and 7-cellulose are mixtures which contain pentosans along with other alkali-soluble extractives.1M0... 

The two most important natural pentoses, 1 -arabinose and 1 -xylose, occur in nature as polymeric anhydrides, the so-called pentosans, viz. araban, the chief constituent of many vegetable gums (cherry gum, gum arabic, bran gum), and xylan, in wood. From these pentapolyoses there are produced by hydrolysis first the simple pentoses which are then converted by sufficiently strong acids into furfural. This aldehyde is thus also produced as a by-product in the saccharification of wood (cellulose) by dilute acids. Furfural, being a tertiary aldehyde, is very similar to benzaldehyde, and like the latter undergoes the acyloin reaction (furoin) and takes part in the Perkin synthesis. It also resembles benzaldehyde in its reaction with ammonia (p. 215). 

Acid hydrolysis of cellulosic materials that include some hemicellulose, produces D-xylose, D-glucose, and cellobiose, as well as 11, 2-furalde-hyde (5), levulinic acid, formic acid, and acetic acid. In order to lessen the contamination due to hemicellulose, acid hydrolysis is generally performed in two steps dilute sulfuric acid (1%) at 80-120° followed by 5-20% sulfuric acid at 180°. The initial stage removes most of the pentogly-cans (pentosans). 

China Quercus acutissima Carr. Q. dentata Thunb. Q. liaotungensis Koidz. Q. mongolica Fisch. ex Turcz. Q. variabilis Blume Lignin, cellulose, protein, pentosan, galactan.56 Promote absorption of tuberculous nodules, remedy for diarrhea, hypertrophy of the gastrointestinal tract, root makes a cleansing dressing for foul sores. 

New International Dictionary, Merriam Co, Springfield, Mass(195I), 73 Alperox C. Trade name for tech lauroyl peroxide manufd by the Lucidol Division of Wallace Tieraan, Inc, Buffalo, NY Alpha-Cellulose is that portion of cellulosic materialfpulp, paper, etc) which,after treatment with 17,5% NaOH(mercerized strength) at 20° and diln to 7.3% NaOH,can be separated by filtration. The residue of alpha-cellulose is a good index of the undegraded cellulose content of the material. The alkali treatment removes degraded(oxidized or hydrolyzed) cellulose and short chain material. Some pentosans and hexosans may... 

Finishing wood cellulose. The finishing process is made to obtain a higher a-cellulose content and to endow the wood pulp with a shape conducive to easy nitration. This is the last operation prior to nitration. It consists in removing hemicelluloses, pentosans, and hexosans, which are undesirable ingredients of wood pulp. An insufficiently purified wood pulp may contain 5-6% of pentosans, straw cellulose even as much as 20%, whereas cotton does not contain more than 0.5-0.6%. 

According to the present theory (e.g. Zherebov [1]) most of the hemicelluloses, pentosans and hexosans are removed during sulphitation, because calcium sulphite is capable of forming addition compounds with pentosans. Complete removal of hemicelluloses is only possible however after lignins have been removed, as lignin seems likely to be chemically combined with hemicellulose and thus with pentosans or hexosans. Only rupture of these bonds and the separation of lignins makes it possible to attack the non-cellulosic polysaccharides (Heuser and Haug [2]). 

Another cheap and readily available source of cellulose is the straw of annual plants. This raw material usually contains exceptionally large quantities of mineral matter. In order to separate cellulose the chlorine process is often used. It consists in treating the cellulosic raw material (previously boiled in a 10% sodium hydroxide solution and then in water) with chlorine. The decomposition of lignin, pentosans and other substances takes place and at the same time the cellulose is bleached. Crude cellulose prepared in this way contained 80-92% of a-cellulose and about 1% of mineral matter. 

Naiman and Troitskii [9] have carried out extensive investigations to compare the nitration of cotton with that of cellulose differing in origin and purity from wood pulp, with hydrocellulose and oxycellulose, and with pentosans. The results are collected in Tables 90 and 91. 

No. Material for nitrating Cellulose content % Copper number Pentosans content % Lignin content % Fats, waxes content 0/ /o Ash content %... 

The ratio acid cellulose was 60. The nitration was carried out for 1 hr at 15-18°C. From the values obtained the deleterious effect of pentosans is noticeable since the presence of these compounds reduces the yield and the solubility of the product. The adverse effect of a high percentage of pentosans is less evident when only lower... 

Cellulosic raw materials. Linters or wood pulp cellulose are in use as raw material for manufacturing lacquer nitrocellulose. It is essential to use very well purified and bleached raw material. Wood cellulose should contain mainly a-cellulose. The admissible pentosan content is limited to traces only, because these compounds are a source of products insoluble in organic solvents. Cellophane can also be utilized for nitration. 

Dietary Fiber. Dietary fiber is a broad term that encompasses the indigestible carbohydrate and carbohydrate-like components of foods that are found predominantly in plant cell walls (see Carbohydrates). It includes cellulose lignin, hemicelluloses. pentosans, gums, and pectins. 

PENTOSAN. A complex carbohydrate (hemicellulose) present with the cellulose in many woody plant tissues, particularly cereal straws and brans, characterized by hydrolysis to give five-carbon-atom sugars (pentoses). Thus the pentosan xylan yields the sugar xylose (HOH,C CHOH CHOH CHOH CHO) that is dehydrated with sulfuric acid to yield furfural (C5H4O2). 

Most of the cells of wood are long, narrow hollow fibers and tubular-shaped cells arranged with their long axes parallel to the axis of the tree trunk. Certain food storage cells lie in radial bands, termed wood rays, which are perpendicular to the tree axis. The walls of this complex system of plant cells form the basic framework and material of all wood substance, All wood substance is composed of two basic chemical materials, lignin, and a polysaccharidic system, which is termed holoceliulose. The latter embraces cellulose and the hemicelluloses, a mixture of pentosans, hexosans and polyuronides, and in some instances small amounts of pectic materials. Wood cell wall tissue also always retains small amounts of mineral matter (ash). 

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