SACCHARIDES STRUCTURE BASE: Monosaccharides ( 1 sugar unit); oligosaccharides ( 2 - 10 sugar units); polysaccharides ( more than 10 sugar unit) Monosaccharides 3 – 6 carbon atoms threose – hexose e.g. glucose Oligosaccharides In foods mainly di- and trisaccharides e.g. maltose, sucrose, lactose Polysaccharides e.g. starch, cellulose, glycogen etc. SACCHARIDES IN NUTRITION Non-essential nutrients For human mainly energy source; lower part is used also for structure of tissues In organism: free saccharides – glucose, lactose, glycogen etc. bounded saccharides: - structure compounds – glycoproteins, glycolipids – mainly in cell membranes - other – e.g. ribose in nucleic acids UTILIZABLE SACCHARIDES starch – cereals, potatoes; amylose and amylopectin units; dextrines (maltodextrines) – arising by enzyme (amylases) hydrolysis of starch glycogen – animal polysaccharide – similar structure as amylopectin – in animal localised in muscles and liver – energy reserve sucrose – sugar-beet, sugar-cane maltose - arising by enzyme (amylases) hydrolysis of starch – in malt lactose – milk sugar glucose, fructose – fruits, honey ribose – content in foods is very low – for organisms very important sugar (synthesis of nucleic acids) – ribose is synthesized from glucose Poorly utilizable saccharides Inuline Polyfructosane; sweet taste; utilization in human body to 10 %; digestion mainly in large intestine; inulin can be caused the flatulence Sources: topinambours („sweet potatoes“), yacon (similar plant) Flatulence factors Unusual di- and trisaccharides (raffinose, galacto inositol, etc.) Digestion by micro-flora of large intestine (about 10 %); formation of gases (carbon dioxide, methan, sulphan etc.) → flatulence Sources: mainly legumes Non-utilizable sacharides Dietary fibre Cellulose – cereals, vegetables, partially fruits Pectin – fruits, partially vegetables CH CH CH 2 OH O OH aldose CH 2 C CH 2 OH OH O ketose
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- Fall '16
- Jeff Miller