Maize Starch for Industrial Applications - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 172

Fig. 9.2 Viscosity profile of dent, waxy, and high-amylose starch in response to heat
ratio. Additionally there is also a limited commercial market for high-amylose
starch that has 55 % amylose and 45 % amylopectin.
Regular starch, made from yellow dent corn, is most readily abundant and can be
most economically produced. However, because of limited functionality, it often
must be chemically or physically modified to provide improved utility in food and
nonfood uses.
Starch functionality can refer to the properties of the granule, or may refer to the
starch matrix that associates the following disruption of granule structure. In
response to heat, pressure, or chemical input, the amylopectin and amylose mole-
cules are released from the granule structure and reassociate to form a gel or film.
The granule will maintain itself to a variable degree dependent on amylose-to-
amylopectin content, degree of amylopectin branching, branch length, and
intermolecular bonding that occurs. The swelling and collapse of the granule
structure is described as gelatinization, and regular, waxy, and amylose starches
display characteristic profiles in response to heat and moisture (Fig. 9.2 ).
Chemical or physical modification is often performed after the initiation of
gelatinization but prior to granule breakdown. Typical industrial applications of
native and modified regular, waxy, and amylose starches are listed in Table 9.1 .
Industry wide approximately 40 % of wet-milled starch is used for nonfood
applications. The most predominant industrial uses are papermaking, corrugating,
laundry, gypsum wallboard construction, and adhesives.
High-amylose starches, valued for their use in corrugating, are of growing
importance in the bioplastic industry. The long straight chains of the amylose