Physical and Chemical Properties
How does the bonding influence the chemical and physical properties ie. How does the bonding, and over all "structure" affect the properties and uses of the material? Eg. Solubility (if at all), temperature range, chemical and physical sensitivities etc.
Solubility: Glucose (a monosaccharide) is soluble, however because starch is a polyssarcharide, the bonds between the thousands of glucose molecules prevent it from dissolving in water. The hydrogen bonds in starch also prevent its solubility at room temperature. However it will become soluble when heated as hydrogen bonds are broken and water penetrates, causing the granules swell and burst, allowing structure to be lost. On the contrary, the smaller amylose molecules begin to leach out of the granules, forming a network which allows it to become semifluid in consistency. This process is called starch gelatinization. Once this paste is cooled, its semi-crystalline structure partially recovers and increases further in viscosity, also realising water.
Starch molecules are broken down by enzymes known as amylases. The digestibility of a specific starch is influenced by its physical form. In plants starch is present in microscopic granules, which impair the enzymatic digestion of starch molecules obtained from plants. Cooking starch-containing items results in the hydration of starch molecules and the swelling of starch granules, increasing the rate and enhancing the enzymatic breakdown of starch. Amylases also convert starch to glucose.