| Starch is one of most widely distributed material in nature. It is contained
in most plants and formed in the leaves and green parts of plants through
the assimilation with the help of enzymes from energy of the sun, water
and carbon dioxide. Starch is stored in seeds of rice, wheat and corn,
in tubers of potato, sweet potato and tapioca. It is known that these starches
are macromolecular materials in linear and/or branched polymer of a few
hundreds to some ten thousands of glucose units. It consists of amylose
and amylopectin. Starches extracted from seeds and tubers are white and
fine powdery materials and the size and shape of particles vary depending
on the sort of starch and the ratio of amylose and amylopectin is also
varied. Adding water to starch, it is not soluble but precipitates. It swells up
to some tens of times or more by heating and then gelatinized with viscosity. If it is left as is, it starts to cloud and turns to gel. Main ingredients
of modified starch are potato starch, corn starch, tapioca starch and so
forth. These raw starches are processed to modified starches making best
use of each characteristic. |
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