Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
However, modified enzyme patterns in starch-containing crops modify starch
glucan composition on a molecular level and result in new or adjusted quality profiles
of starch raw materials. This leads to many and mutual influences (Figure 22.1) on
the formation process of starch, any efficient technological utilization of these
materials requires comprehensive analysis, and initial selection of raw materials and
quality control during processing become important factors.
Physicochemical characteristics such as disintegration temperature and swelling
behavior of starch granules in aqueous media provide basic information for classification
of technological starch properties. Depending on source and harvesting
period, dimension of starch granules range between 2 and 140 µm. They swell
continuously if suspended in water and even more at elevated temperatures. However,
at a certain temperature, the gelatinization temperature, the swelling process becomes
irreversible and further increase of temperature disintegrates the granules on a
molecular level. The process can readily be monitored with increasing optical transparency
and decreasing viscosity of heated starch suspensions.
Temperature–time profile of Brabender viscosity of a wheat glucan–water suspension,
for instance, initially shows a broad disintegration window and relatively
low increase of viscosity; however, at a final period of decreasing temperatures, a
pronounced reorganization capacity is indicated by a significant increase of viscosity.
At identical conditions, waxy maize runs through a narrow disintegration phase
between 65 and 75°C correlated with initially pronounced increase of viscosity.
After disintegration, viscosity decreases, and even in the cooling period, waxy maize
glucans keep their status and show no significant reaggregation (Figure 22.2). The
consequences of these differences become obvious in technological properties such
as freeze–thaw stability: comparably high stability of paste, high viscous waxy
Breeding
Environmental/biological
Biochemistry conditions
Molecular Biology
Technological
Processing
Enzymatic Granular properties
activities
Polysaccharide Characteristics
Molecular conformation
Branching pattern
Status of oxidation
Molecular dimensions
Interactive potential
Molecular/Supermolecular
Analysis/Characterization
Lipids, proteins,
salts, water, ...
FIGURE 22.1 Controlling influences on starch polysaccharide characteristics.