Amylose
Structural formula | |||||||
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Structure of amylose: the number of monomer units n is between 100 and 1400, depending on the source |
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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 |
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properties | |||||||
Physical state |
firmly |
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safety instructions | |||||||
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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) |
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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
- ↑ Data sheet Amylose from potato, used as amylase substrate from Sigma-Aldrich , accessed on December 27, 2012 ( PDF ).
- ↑ Walther Burchard , Polysaccharide: Properties and Use - An Introduction , p. 31, Springer Verlag 1985.
- ↑ 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 .
- ↑ FA Schüll (dissertation): Influence of specific properties of starch on the brewing process , Technical University of Munich 2012, pp. 11–12.
- ↑ Habermehl, Hammann, Krebs: Naturstoffchemie. An introduction . 2nd Edition. Springer, Berlin 2002, ISBN 978-3-540-43952-3 .
- ↑ B. Pfannemüller and G. Ziegast: Resonance Raman spectroscopy on amylose-iodine complexes . In: Starch 35 , 7-11 (1983), doi : 10.1002 / star.19830350104 .