Lecture 6 CHO Classification & Function Flashcards
What are the main elements contained in CHO, proteins, lipids and vitamins?
- Hydrogen
- Carbon
- Nitrogen
- Oxygen
- Phosporus
- Sulphur
Why is CHO considered hydrated carbon?
H to O ratio is 2:1 just like water
Macronutrient DRIs of digestible CHO
~130 AI
Macronutrient DRIs for fibre
CHO AMDRs
45-65%
Classification of CHO
Classified as either simple or complex
* simple: monosaccharides and disaccharies
* complex: oligosaccharides and polysaccharides
Common monosaccharides
- glucose
- fructose
- galactose
Common disaccharides
- lactose
- sucrose
- maltose
Common oligosaccharides
- raffinose
- stachyose
- verbascose
Common polysaccharides
- Starch
- glycogen
- dietary fibre
Basic features of monosaccharides
- Aldose (-ose, 1 aldehyde, 1C) or ketose (-ulose, 1 ketone, 2C)
- Triose, tetrose, pentose, hexose, heptose, octose, nonose
- D or L- based on the chirality
Identify
monosaccharide - glucose
Identify
Galactose
Identify
Fructose
What is bond that links monosaccharides?
glycosidic bonds
Formation of glycosidic bonds
Formed by condensation reaction of hydroxyl (-OH) of one molecule with a hydrogen atom (H) of another s and forming a molecule of water
How are glycosidic bonds named?
The numbers in a glycosidic bond refer to the carbon atoms that form the bond.
* glycosidic bond facing down: 𝝰 glycosidic bond
* glycosidic bond facing up: β glycosidic bond
What is the glycosidic bond of maltose?
a-1,4 glycosidic bond
Basic features of disaccharides, oligosaccharides and polysaccharides?
- Consists of 2+ monosaccharides formed via glycosidic linkages
- Require specific enzymes for hydrolysis during digestion
- Reducing or non-reducing
What are the branching structures of polysaccharides?
- Linear polysaccharides
- Alternating single sugar unit branches on linear polysaccharide
- Blocks of consecutive single sugar unit branches on linear polysaccharide
- Ramified structure, branches on branches
What are reducing sugars?
Sugars that contain aldehyde groups & have an open chain form and can therefore react. The free anomeric -OH are free to react
* reduction
* oxidation
* isomerization
Maillard reaction
Reaction between a CHO and an amine group to form glycosides
Louis Camille Maillard
Maillard reaction
Shows how reducing sugars reacted whereby they reacted with glycoproteins to create a browning effect
Louis Camille Maillard
Reactivity of amines with aldoses
Initiation of the Maillard reaction
* aminoketose formed can undergo a cascade of reactions
