From plant cell walls

Milieu conditions in gastrointestinal tract can influence the pectin structure and properties. Under the acid conditions of the stomach (pH 2-4) extraction of pectin from plant cell walls and hydrolysis of side chains can occur. In small intestine (pH 5-6) -elimination of main chains or de-esterification seems to be possible. In caecum and colon (pH 6-8) a strong fermentation of pectin takes place causing depolymerization to oligomers and leading to formation of short chain fatty acids and gases. The presence of OligoGalA is not yet clarified. 

The starches, the most important vegetable reserve carbohydrate and polysaccharides from plant cell walls, are discussed in greater detail on the following page. Inulin, a fructose polymer, is used as a starch substitute in diabetics dietary products (see p.l60). In addition, it serves as a test substance for measuring renal clearance (see p.322). 

Plant foods are an important component of the diet of humans. Since the cell wall makes up a large component of the dry weight of plant tissues, and because in a normal diet most of the dietary fiber comes from plant cell walls, it follows that there is a need to know the composition of the cell walls. Moreover, the cell wall contributes (along with turgor pressure and the cell contents) to the texture of plant foods, and since humans consider the texture of foods an important sensory attribute, again, understanding wall composition is important. 

As Stopes seems to have anticipated, a large number of macerals have been identified and named. All macerals, however, can be conveniently grouped into three major subdivisions -vitrinite, liptinite, and inertinite. The vitrinite group of macerals are derived from plant cell wall material (woody tissue) and usually make up 50-90% of most North American coals. Although there are a large number of named varieties of... 

Atalla RH, Agarwal UP (1986) Recording Raman spectra from plant cell walls. J Raman Spectrosc 17 229- 231... 

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