Starch Nanocomposite and Nanoparticles: Biomedical Applications - Modern Trends in Chemistry and Chemical Engineering - page 51

Figure 3.1. Crystalline nature of starch.
The C pattern is a mixture of both A and B types, but also occurs naturally, for ex-
ample smooth-seeded pea starch and various bean starches. The V-type conformation is
a result of amylose being complexed with substances such as aliphatic fatty acids, emul-
sifi ers, butanol, and iodine.The main difference between A and B types is that the former
adopt a close-packed arrangement with water molecules between each double helical
structure, while the B-type is more open, there being more water molecules, essentially
all of which are located in a central cavity surrounded by six double helices (Fig. 3.1).
Amylose molecules consist of single mostly unbranched chains with 500-20,000
α-(1, 4)-D-glucose units dependent on source (Scheme 3.1).
Scheme 3.1. Structure of amylose.
Amylose can form an extended shape (hydrodynamic radius 7-22 nm) but
generally tends to wind up into a rather stiff left-handed single helix or form even
stiffer parallel left-handed double helical junction zones. Single helical amylase has