163
8
Regardless of the chemical structure of starch
and the respective superstructures, several starch
molecules form so-called starch grains in the
respective storage organs of the plants. These
grains differ significantly in size and shape, and
their appearance depends specifically on the type
of plant (. Fig. 8.3).
5 The ratio of amylose to amylopectin strongly
depends on the plant from which the corresponding starch is obtained. To put it simply,
plants contain about two to four times more
amylopectin than amylose. A detailed list
of the respective proportions is given in
. Table 8.1.
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
OH
HO
HO
OH
OH
HO
OH
OH
HO
HO
HO
OH
HO
HO
OH
OH
OH
OH
HO
OH
HO
OH
OH
HO
OH
OH
HO
HO
HO
OH
HO
HO
OH
OH
OH
OH
HO
OH
OH
OH
OH
OH
OH
OH
HO
HO
HO
OH
HO
HO
OH
HO
OH
HO
. Fig. 8.2 Schematic illustration of the helical structure of amylose
. Table 8.1 Starch content of various plants, share of amylose and share of total annual starch production
(World 2017)
a Percentage of 85 Mio. tons of starch produced in 2017
Crop
Starch content (%)
Amylose content of starch (%)
Share of production (%) a
Potato
15
24
Manioc (= Cassava)
13
20
15
Wheat
74
25
6
Corn
64
26
74
Waxy corn
1
Amyl corn
60–85%
Pea
~65
35
< 1%
Rice
89
18
8.1 · Structure and Occurrence