Lignocelluloses in nature

Peroxidase has been implicated in the formation of the grit cells or stone cells of pears (Ranadive and Haard 1972). Bound peroxidase but not total peroxidase activity was higher in the fruit that contained excessive stone cells. The stone cells or sclereids are lignocellulosic in nature. The presence... 

The use of cellulosic fibers in polymer composites has increased in the last decade. The reinforcing ability of natural fibers is governed by the nature of cellulose and its crystallinity. Natural fibers are generally lignocellulosic in nature [1], The main constituents of cellulosic (natural fibers) fibers are shown in Figure 12.1. 

Up to about 70 C, plant tissues are thermally stable, as they must be in nature to avoid damage from prolonged direct exposure to the sun. Pyrolysis, the chemical decomposition by heat, starts in dry lignocellulosics around 100 C, in moist ones below 80 C. It accelerates as temperature rises, peaking in many organic materials between 275 and 300 C, at which point cellulose disintegrates. 

Dev, S. (1989). Terpenoids. In Natural Products of Woody Plants II Chemicals Extraneous to the Lignocellulosic Cell Wall, ed. Rowe, J.W., Springer-Verlag, Berlin, pp. 691 807. 

Cellulose is found in nature in combination with various other substances, the nature and composition of which depend on the source and previous history of the sample. In most plants, there are three major components cellulose, hemicelluloses, and lignin. Efficient utilization of all three components would greatly help the economics of any scheme to obtain fuel from biomass. Hemicelluloses, lignocellulose and lignin remaining after enzymatic degradation of the cellulose in wood would require chemical or thermal treatment - as distinct from biochemical - to produce a liquid fuel. 

Carbohydrates would be the predominant raw materials for future biorefineries. The major polysaccharides found in nature are cellulose, hemicellulose and starch (see Chapter 1). These molecules would be mainly utilised after they are broken down to their respective monomers via enzymatic hydrolysis, thermochemical degradation or a combination of these two. Cellulose and hemicellulose, together with lignin, constitute the main structural components of biomass. Starch is the major constituent of cereal crops. This section would focus on the potential utilisation of carbohydrates and lignocellulosic biomass for chemical production. 

Hemingway, R. W. In Natural Products Extraneous to the Lignocellulosic Cell Wall of Woody Plants Rowe, J. W., Ed. Springer New York, Chapter 6.6 (in press). 

Lignocellulosics are the most abundant renewable resource in the world, and bioconversion of lignocellulosics into fiiel ethanol could contribute to renewable energy supplies. Hemicelluloses, the second most abundant polysaccharides in nature, represents about 20-30% of agricultural residues [1], The utilization of hemicellulose is essential for whole components utilization of lignocellulosic materials, as well as for the economy of the bioconversion process in industrial applications. 

Kolattukudy P.E., EspeUe K.E., Chemistry, biochemistry, rmd function of suberin and associated wrixes, in Natural products of woody plants, chemical extraneous to the lignocellulosic cell wall, Ed. Rowe J., Springer, Berlin, Heidelbeig, 1989. 

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