What it is and where it is
Cellulose is an organic compound that is widespread in nature because it is a support fabric for plant tissues. Therefore it also abounds in cereals, in fruit and especially in bran and in some vegetables (radicchio and lettuce); however, the human organism cannot digest it, as it lacks enzymes that can break it down into simpler and assimilable substances. Consequently, the cellulose is free of calories and is expelled with the feces, to which it gives volume and consistency; due to these characteristics, it is considered an insoluble dietary fiber.
Features and Properties
Cellulose has strong hygroscopic properties (it absorbs environmental humidity, increasing up to 10 times its own weight); the ability to incorporate large quantities of water means that after ingestion, which reaches the gastrointestinal tract, swells, increasing the volume and weight of the stools, but also satiety and peristaltic movements.
The mildly laxative effect makes it useful in the presence of constipation, while it is contraindicated in all conditions of increased intestinal motility (diarrhea, irritable bowel).
Arriving almost unchanged up to the colon, cellulose is partially fermented by the local microbial flora, releasing fatty acids with a laxative effect. The same fatty acids promote the health of the intestinal mucosa and, by virtue of their acidity, create favorable environmental conditions for the growth of good, but hostile bacteria for pathogens.
What differentiates it from the Starch
Starch and cellulose, while sharing plant origin and being both made up of glucose, are quite different polysaccharides, both in structural and functional terms: starch is the energy reserve of the plant, while cellulose is the basis of its structure (roots, stems and leaves).
From the chemical point of view, however, this difference is very subtle and simply due to the way in which the various glucose units are joined together. In fact, cellulose is a polysaccharide, just like starch. It is distinguished by being formed by a linear (rather than branched) chain of various monomers of B-glucose (α-glucose in starch), linked together through a B 1, 4 bond. It is these ties that are inseparable from human digestive enzymes (which manage to break up the α-glycosidic enzymes of starch). On the contrary, in the rumen of some animals and in the digestive tract of insects that feed on wood, there are microbes ( Ruminococci and Bacteroides succinogenes ) endowed with particular enzymes (cellulase and cellobiasis), capable of transforming cellulose into sugar.
Excluding the two terminal units, cellulose has a raw formula (C 6 H 10 O 5 ) n . Depending on the source and the botanical species, the glucose units for each macromolecule range from 300 to 10, 000; the greater this degree of polymerization and the higher its commercial value.
hemicellulose
Hemicellulose is an organic polymer very similar to cellulose, from which it differs for its low degree of polymerization (<pm) and for being also constituted by other monosaccharides (xylose, mannose, arabinose).
Purposes
The most valuable cellulose is obtained from cotton (it contains 90-95%), but is also obtained from wood (it contains 40-50%) and straw.
Cellulose is widely used not only in the diet sector (useful in slimming programs and as a laxative), but also in the pharmaceutical sector (production of gauzes and coatings capable of modulating the release of active ingredients from the tablet), cosmetic (for the preparation of gel, stabilizers, film-makers, dentifrices), war (manufacture of explosives), textiles (rayon, lyocel) and in many others (the use of cellulose is famous for the production of paper).
