The second one is amylopectin, a non-linear and highly
∗ Corresponding author. Tel.: +58 212 9063976; fax: +58 212 9063971.
E-mail address: asandova@usb.ve (A.J. Sandoval).
branched molecule. The arrangement of these biopolymers in the
grain forms semi-crystalline superstructures, with crystalline and
amorphous layers arranged in an onion like structure. Although,
it depends on the botanic origin of the starch, crystalline regions
are associated with amylopectin small side-chain parallel clusters,
although parts of the amylose molecules are also present in them.
Within such a system, the crystalline structure includes a fixed
number of water molecules, while the amorphous zones adsorbs
an increasing amount of moisture depending on the relative
humidity of the atmosphere where the samples are being equilibrated.