Saccharides in nutrition-text.doc - SACCHARIDES STRUCTURE...

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