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Classification of Carbohydrates

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Carbohydrates

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Carbohydrates

Can be divided in two groups

1-Sugars and

2-Non Sugars

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Classification of Carbohydrates �( sugars) �

  • Number of carbohydrate units

monosaccharides: one carbohydrate unit

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disaccharides: two mono saccharides units

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trisaccharides: three mono saccharides units

Oligo Saccharides: few Mono Saccharides

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1.Monosaccharides

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Trioses (C3H6O3)� 

Glycerose (glyceraldehyde)

Dihydroxyacetone

Tetroses (C4H8O4)� 

Erythrose

Erythrulose

Pentoses (C5H10O5)� 

Ribose

Ribulose

Hexoses (C6H12O6)� 

Glucose

Fructose

Heptoses (C7H14O7)� 

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Sedoheptulose

ALDOSES KETOSES

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Monosaccharides�(monos)

The Most Important Monosaccharide Is Glucose.

  • A Monosaccharide is made up of 1 sugar unit.
  • Monos are reducing sugars.
  • Fructose and Galactose are all so Monosaccharides, They all have the same chemical formula but different structures.

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Glucose

  • The chemical formula for glucose is C6H12O6.
  • It is a six sided ring.
  • The structure on the left is a simplified structure of glucose

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Glucose

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Fructose

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Galactose

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  • D-galactose

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Mannose

  • Epimer of glucose at C-2
  • After ingestion converted to glucose.
  • Occur as part of some poly saccharides

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Oligosaccharides

  • Most common are the disaccharides
      • Sucrose, lactose, and maltose
      • Maltose ( 2 molecules of D-glucose)
      • Lactose (a molecule of glucose and a molecule of galactose)
      • Sucrose (a molecule of glucose and a molecule of fructose)

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Sucrose

  • also known as table sugar
  • commercially obtained from sugar cane or sugar beet

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Lactose

  • β-D-galactose joined to α−D-glucose via β (1,4) linkage
  • Called Milk sugar
  • β-lactose is sweeter and more soluble than ordinary α- lactose

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Maltose

  • 2-glucose molecules joined via α(1,4) linkage
  • known as malt sugar
  • produced by the partial hydrolysis of starch (either salivary amylase or pancreatic amylase)
  • Found in beer and malt liquors
  • used as a nutrient (malt extract; Hordeum vulgare); as a sweetener and as a fermentative reagent

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Classification of PolySaCCHarides

  • 1- Storage
  • 2- Structural

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Polysaccharides(complex carbohydrates)

  • homoglycans (starch, cellulose, glycogen, inulin)
  • heteroglycans (gums, mucopolysaccharides)
  • characteristics:
      • polymers (MW from 200,000)
      • White and amorphous products (glassy)
      • not sweet
      • not reducing; do not give the typical aldose or ketose reactions)
      • form colloidal solutions or suspensions

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Starch

  • most common storage polysaccharide in plants
  • composed of 10 – 30% α−amylose and 70-90% amylopectin depending on the source
  • Common sources are grains , potatoes, peas, beans, wheat

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Glycogen

  • also known as animal starch
  • stored in muscle and liver
  • present in cells as granules (high MW)
  • contains both α(1,4) links and α(1,6) branches at every 8 to 12 glucose unit
  • complete hydrolysis yields glucose

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DEXTRIN

  • Obtained from hydrolysis of starch & glycogen.
  • Used to produce a characteristic flavor to bread crust, cereal foods and toasts.
  • Other uses------?

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Types of DEXTRINS

Erythro Dextrins

Achro dextrins

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Amylo Dextrins

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CELLULOSE

  • Most abundant plant constituent.
  • Present as chemically linked with hemi cellulose and lignin.
  • Pure form-------
  • Fermentation results in production of VFAs

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Cellulose

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Hetero PolySaccharides

  • Hemicellulose
  • Gums
  • Mucilages

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Hemicellulose�