Carbohydrates are the most abundant and diverse class of organic compounds occurring in nature. They are also one of the most versatile materials available and therefore, it is not surprising that carbohydrate-related technologies have played a critical role in the development of new products ranging from foods, nutraceuticals, pharmaceuticals, textiles, paper, and biodegradable packaging materials.
Carbohydrates played a key role in the establishment and evolution of life on earth by creating a direct link between the sun and chemical energy. Carbohydrates are produced during the process of photosynthesis:
Carbohydrates are widely distributed both in animal and plant tissues,
where they function as:
• Energy reserves (e.g., starch, fructans, glycogen).
• Structural materials (e.g., cellulose, chitin, xylans, mannans).
• Protective substances. Some plant cell wall polysaccharides are elicitors of plant antibiotics (phytoalexins). In soybean, fragments of pectic polysaccharides ( α -4-linked dodecagalacturonide) induce synthesis of a protein (protein inhibitor inducer factor) that inhibits insect and microbial proteinases. Arabinoxylans have been postulated to inhibit intercellular ice formation, thus ensuring winter survival
of cereals.
• Cell recognition moieties. Oligosaccharides conjugated to protein (glycoproteins) or to lipids (glycolipids) are important components of cell membranes and can be active in cell to cell recognition and signalling. It is recognized that oligosaccharide moieties serve as probes through which the cell interacts with its environment. In addition, the environment delivers signals to the interior of the cell through the cell surface oligosaccharides.
• Information transfer agents (nucleic acids).
6CO2 + 6H2Ohγ→C6H12O6 + 6O2
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