Chemical structures, including amylose contents, amylopectin molecular sizes, branch chain lengths and distributions, and starch phosphate monoester and phospholipid contents, of a wide varieties of starches were analyzed. Thermal properties of starch gelatinization and retrogradation and starch pasting properties were also investigated. Results of the studies have shown that amylopectin branch chain lengths and their distributions govern the starch gelatinization temperature. Short average branch chain lengths and large proportions of short branch chains (DPI 1-16) relative to chains of DP 18-20 (a shoulder found in many starches) are likely to result in low gelatinization temperatures. Phosphate monoester derivatives also lower gelatinization temperature. With the same amylopectin structure, increasing amylose contents lower the starch gelatinization temperature. Methods of starch isolation also affect starch gelatinization temperature. Amylose contents significantly affect the pasting properties of starch. Normal cereal starches contain lipids and phospholipids, which display higher pasting temperatures, lower peak viscosity, and lower shear thinning than their waxy starch counterparts. Without lipids, normal potato starch displays a higher peak viscosity than waxy potato starch. Branch chain length of amylopectin also affects the pasting properties of starch. The presence of very long branch chains restrict starch swelling and increase the pasting temperature of starch and decrease the shear thinning. Phosphate monoester derivatives decrease the pasting temperature and enhance the viscosity by charge repelling. In contrast, phospholipids, by complexing with amylose and long branch chains of amylopectin, restrict the starch swelling and reduce the viscosity.