by Mathieu Calmont, Borregaaard LignoTech, Norway
Starch is one of the primary ingredients used in feed, together with protein. But starches from different sources offer a range of functional properties that need to be considered, not only from a nutritional perspective but also for technological aspects.
Starch is one of the primary ingredients used in feed, together with protein. But starches from different sources offer a range of functional properties that need to be considered, not only from a nutritional perspective but also for technological aspects.
Chemically, starches are polysaccharides that consist of repeating glucose units. Starch molecules have one of two molecular structures: a linear structure, known as amylose; and a branched structure, known as amylopectin.
Amylose and amylopectin associate through hydrogen bonding and arrange themselves radially in layers to form granules. Starches from different sources vary from one another in the following ways - each of which may affect performance:
Granule size and shape
Starch granules come in a wide variety of sizes ranging from three microns to over 100 microns. Wheat starch, for example, has a distribution of both large and small granules while corn-starch has a narrow distribution of rather large granules.
Amylose: amylopectin ratio
All starches are composed of varying proportions of amylose and amylopectin. The ratio varies not only among the different types of starch, but also among the many plant varieties within a type. Waxy starches are those that have no more than 10 percent amylopectin.
Standard wheat and corn starches contain 25-to-28 percent of
amylose and 72-to-75 percent of amylopectin, not a big difference for this
specific parameter. Other variations also exist in starches. In general, most
such variations consist of the presence of non-starch components in the granule
(or close to), such as lipids or protein. Those elements can highly influence
gelatinisation, even at low concentration.
Corn
Four classes of corn-starch exist. Common corn-starch has 25 percent amylose, while waxy maize is almost totally composed of amylopectin. The two remaining corn starches are high-amylose cornstarches; one has 50-to-55 percent amylose, while the second has 70-to-75 percent. Granule size ranges between 15 microns and 20 microns, quite a narrow distribution.
Corn
Four classes of corn-starch exist. Common corn-starch has 25 percent amylose, while waxy maize is almost totally composed of amylopectin. The two remaining corn starches are high-amylose cornstarches; one has 50-to-55 percent amylose, while the second has 70-to-75 percent. Granule size ranges between 15 microns and 20 microns, quite a narrow distribution.
Read more HERE.
The Global Miller
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