Project on polysaccharides
EPNOE
Our active participation in EPNOE (European Polysaccharide Network of Excellence) is to contribute actively to the aims of the network, which is to bundle the potential of fundamental and multidisciplinary expertise available within the EU on polysaccharide R&D. The importance of polysaccharides for developing the bio-economy is evident.
Fibre crops and polysaccharides
Plant fibres are commonly composed of cellulose microfibrils that are embedded in a matrix of other cell wall components including different hemicellulose polysaccharides (xylan, glucomannan, rhamnogalacturonan, xyloglucan), pectin and lignin (polyphenols). These polysaccharides and their structural assembly are determining the functional properties and economic value of the fibre crop.
Polysaccharides or polyglycans form the class of carbohydrates that are the most widespread biopolymers in nature, with many different properties and roles. The most widespread are cellulose and starch, that are both long chain homopolymers of (1-4) linked D-glucose units, but with respectively beta or alpha orientation of the acetal bond. The intrinsic properties of polysaccharides in their affinity to water and susceptibility to biodegradation have given rise to many derivatives that find commercial use. Typical examples are the cellulose and starch derivatives, which may have thermoplastic properties or are used as surfactant, coating or adhesive.
Other more complex polysaccharides and heteroglycans are involved in numerous other vital functions. These may be composed of sugars other than glucose (such as galactose, mannose, xylose) and are often branched, or contain substituents (acetyl) and functional groups (e.g. carboxyl groups in pectins or amine groups in chitin). These types of polysaccharides can be found in cell walls of many bacteria, fungi, plants and some tissues of animals. Only a few are used for commercial purposes outside the food and animal feed industries (gelling agent and gums). Polysaccharides of commercial interest such as hyaluronan (derived from animal tissues) or alginates (from seaweeds) are important in pharmaceutical and health care industries.
Dietary fibres and neutraceuticals
Polysaccharides also play a key role in human health and well being. Within the EPNOE network other non-food polysaccharide applications are elaborated, such as the development of novel uses in pharmaceutical and medical industries. The importance of carbohydrates as major food ingredient supplying energy and essential building elements for construction of healthy tissues is well known. In recent years the role of non-digestible polysaccharides (NDPS) in food has been recognized and NDPS are now finding entrance to the market as functional food ingredients and prebiotics. A wide variety of plant polysaccharides such as soluble beta-glucans, arabinoxylans, fructans (inulin) and pectins have been investigated for their potential as dietary supplements or smart food additives. Nutraceuticals are becoming more and more important in food industries and many new functional roles for polysaccharides and their derivatives in health food will be developed in the near future.
Bio-economy and bio-refinery
Feedstock supply and conversion processes are the key issues for the transition towards the bio-based economy . Contents of sugar and carbohydrates (polysaccharides, starch and cellulose) are the key components for driving bio-processes. Therefore, novel bio-refinery technologies need to be designed, when sustainable use of resources is required.
Bio-refinery is analogous to the petroleum refinery. The biomass is “cracked” into separated components and each is converted to a separately marketed product. A bio-refinery, then, is as a processing unit that refines biomass. This definition includes existing processing plants wherein carbohydrates (sugar, starch, cellulose and other polysaccharides), lipids and protein from crops are converted to products and fuel, sugars, ethanol, organic acids and (bio)polymers.
Further reading:
- Website of EPNOE
- Palm oil production for oil and biomass; The solution for sustainable oil production and certifiably sustainable biomass production? (PDF)
- J.E.G. van Dam, B. de Klerk-Engels, P.C. Struik, R. Rabbinge, -“Securing renewable resources supplies for changing market demands in a biobased economy”- Ind. Crops and Prod 21 (2005), 129-144.
- Jan E.G. van Dam and Seetharam Annadana - Industrial Biotechnology for energy and materials in a Biobased Economy: Opportunities and threats for the developing world, International J. Biotechnology 2006 (submitted)
- Oleg P. Gurjanov, Tatyana A. Gorshkova, Mirjam Kabel, Henk Schols, Jan E.G. van Dam – MALDI-TOF evidence for the linking of flax bast fibre galactan to rhamnogalacturonan backbone. Carbohydrate Polymers (in press) 2006.
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