Amylose

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Structural formula
Structure of amylose

Structure of amylose: the number of monomer units n is between 100 and 1400, depending on the source
General
Surname Amylose
CAS number 9005-82-7
Monomer D - glucose
Molecular formula of the repeating unit C 6 H 10 O 5
Molar mass of the repeating unit 162.14 g mol −1
Type of polymer

Polysaccharide

properties
Physical state

firmly

safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Amylose (Greek amylon , 'cornstarch'), with a mass fraction of around 20–30 percent, is, along with amylopectin, a component of natural, plant-based starch , for example from potatoes , wheat or corn .

Table : amylose content of various starches, the remainder ad 100 is amylopectin.

isolated strength
of
Amylose content
(g / 100g)
tapioca 20th
potato 21st
wheat 23
Corn 27
Waxy maize 0
Amylomais 50-80
Smooth pea 36
Shrink pea 69
Amflora potato 0

The polysaccharide amylose has a molar mass of 100000-1000000 g · mol -1  , equivalent to about 1000 (in cereal starches) to 4500 (for potato starches) D - glucose - monomers , the α -1,4 glycosidic are interconnected. With a high molar mass , isolated α- 1,6- glycosidic branches also occur.

Due to the bond angle between the building blocks, the chain is wound in a helical shape with about 6 building blocks per turn. Hydrogen bonds between neighboring hydroxyl groups stabilize the structure. In the cavity of the helix other molecules, e.g. B. iodine , are included. This results in a deep blue-violet colored iodine-starch complex, which serves as qualitative evidence.

Amylose is somewhat soluble in water; colloidal , it dissolves well in hot water. Amylose pastes form a gel and tend to retrogradation . The addition of Lugol's solution turns amylose blue (“Lugol's strength test”). In the case of very short-chain amylose the coloration can be faintly red-violet, in the case of long-chain amylose it can be intense blue.

Individual evidence

  1. Data sheet Amylose from potato, used as amylase substrate from Sigma-Aldrich , accessed on December 27, 2012 ( PDF ).
  2. Walther Burchard , Polysaccharide: Properties and Use - An Introduction , p. 31, Springer Verlag 1985.
  3. C. Bächtle, P. Winkler and B. Stellbrink (BASF): A question of the right strength . In: Chemistry in our time 45 , 250–255 (2011), doi : 10.1002 / ciuz.201100543 .
  4. FA Schüll (dissertation): Influence of specific properties of starch on the brewing process , Technical University of Munich 2012, pp. 11–12.
  5. Habermehl, Hammann, Krebs: Naturstoffchemie. An introduction . 2nd Edition. Springer, Berlin 2002, ISBN 978-3-540-43952-3 .
  6. B. Pfannemüller and G. Ziegast: Resonance Raman spectroscopy on amylose-iodine complexes . In: Starch 35 , 7-11 (1983), doi : 10.1002 / star.19830350104 .