Abstract
Differential thermal analysis was carried out on starches from several
different botanical sources, and of their component amylose and amylopectin,
and the thermograms compared. It was found that the presence of "inert"
materials such as alumina profoundly affected the thermograms or starch.
All analyses had therefore to be carried out without the addition of any
"inert" material. Factors affecting the starch thermograms, such as the
physical structure of the granule and percentage amylose content, were
investigated. It was noted that thermograms similar to those of starch were
obtained from the oligomer series G₁ to G₇, where thermal stability of these
oligomers was found to increase with increase in their chainlength.
The pyrolysis over a temperature range of 220 to 300°C of the oligomer
series,G₁ to G₇, ß-Schardinger dextrin, potato starch and its components
amylose and amylopectin, retrograded amylose, and dextran was studied. The
amounts of the various products from each substance at the different temperatures
were compared.
Rates of production of the major volatiles, i.e. carbon monoxide, carbon
dioxide and water, from each of the compounds were measured at the various
temperatures, and activation energies for the degradation calculated. The
natures of the residues and 'syrup' fractions were investigated. The
influence on the thermal breakdown of temperature, molecular size and type
of glycosidic linkage were studied. The significance of these results is
discussed and possible modes of degradation are suggested.
