Biomedical Engineering Reference
In-Depth Information
Chapter 9
Maize Starch for Industrial Applications
Brad M. Ostrander
Abstract Starch is used in many industrial applications as viscosifiers, emulsifiers,
defoaming agents, for encapsulation, and as sizing agents. Starches are valued for
their ability to impart textural characteristics and provide gelling or film formation.
Much of the starch used for industrial purposes must be chemically or physically
modified to improve performance or provide functional persistence. Increasingly,
however, as the genetics behind starch biosynthesis are better understood, native
starches can be selected to allow chemical or physical modification protocols to be
optimized or to be more fully utilized as non-modified starches. This review
discusses the types of starch commonly used in industry, the development and
availability of specialty corn types, breeding methods used, and the challenges and
potentials for new approaches.
Keywords Specialty starches • Amylose • Amylopectin • Waxy • High amylose •
Wet milling • Papermaking • Bioplastics
Introduction
Starch provides the maize plant with the energy resource to fuel seedling emer-
gence. Seedling growth and leaf development rapidly increase the plant's photo-
synthetic capability to fix carbon as glucose. The glucose is polymerized by the
plant to form starch, initially in relatively small quantities in the leaves. As the plant
matures and enters the reproductive stage of the life cycle, an increasingly higher
proportion of glucose is sequestered in the endosperm as starch, in the newly
formed, next-generation kernel.
In the endosperm of the maize kernel, starch granule development occurs by
successive layering of starch in crystalline and amorphous configuration (Fig.
9.1
).
Maize starch is classified as either amylopectin or amylose. Amylopectin and
amylose are distinguished by degree of branching and molecule size. Amylopectin
maize is larger than amylose and is composed of 2,000-20,0000
α
-(1
!
4)-linked
glucose units, with branching
α
-(1-
6) linkages occurring every 24-36 units.
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