Raffinose

  • Melitose
  • Melitriose
  • Gossypose
  • α -D - Galactosylsucrose

Colorless prisms

Fixed

80-82 ° C ( pentahydrate )

  • Moderately in water (50 g · l-1 at 20 ° C ) and methanol
  • Poorly in ethanol, insoluble in diethyl ether

Template: Infobox chemical / molecular formula search available

Raffinose is an in plants occurring carbohydrate, specifically a triple sugar ( trisaccharide ). It is composed of three monosaccharides galactose, glucose and fructose.

Biosynthesis

The biosynthesis occurs in plants by a galactosyl residue is transferred to sucrose of galactinol, myo-inositol which is free.

Sucrose galactinol → raffinose myo- inositol.

This reaction is catalyzed by myo -inositol - galactosyl transferase. The galactose is in this case attached in α -1, 6 glycosidic bond, and it follows OD galactopyranosyl - ( 1α → 6) -OD -glucopyranosyl- ( 1α → 2β ) OD - fructofuranoside.

Raffinose family

Of the two other oligosaccharides raffinose derive are attached in which in the same manner starting from the raffinose in α -1 ,6- glycosidic linkages other galactose:

  • Raffinose stachyose galactinol → myo- inositol,
  • Stachyose galactinol → verbascose myo- inositol.

Therefore, raffinose, stachyose and verbascose be referred to as raffinose family.

The compounds have the following molar masses:

  • Raffinose: 504.5 g · mol -1
  • Stachyose: 666.6 g · mol -1
  • Verbascose: 828.7 g · mol -1

Occurrence and function

Raffinose and the raffinose family replaces in some plants the starch as a storage carbohydrate. In larger amounts of raffinose contained in legumes.

For peas and beans they can make 5 to 15 % of dry matter. Raffinose is also contained in sugar cane and sugar beet, accumulates in sugar production but in the molasses to. Raffinose is used in some species ( Cucurbitaceae, linden, elm ) also instead of sucrose as a transport substance in the sieve tubes of the phloem.

Man

Raffinose has only 22% of the sweetening power of beet sugar (sucrose), as increasingly with increasing degree of polymerization saccharides tasteless.

In the small intestine it is digested and absorbed only to a limited extent, since the α - Galaktosidbindung by human digestive enzymes can not be cleaved. As a result, larger quantities pass into the large intestine. The elements on the anaerobic microorganisms of the intestinal flora they use and produce inter alia gases that lead to bloating.

CAS registry number PubChem Vicia faba Tilia
274041
de