Morphological and thermal properties of maize starch.

Maize, rice, wheat and potato are the main sources of starches which differ significantly in composition, morphology, thermal, rheological and retrogradation properties. Starch has unique thermal properties and functionality that have permitted its wide use in food products and industrial applications. The structure of the starch granule results from the physical arrangement of amylose and amylopectin. Amylose content of starches from different maize types ranged between 15.3% and 25.1%. Amylopectin is considered responsible for the crystalline structure of starch granules. The morphological and physicochemical characteristics of maize starch are related to the enzymes involved in its biosynthesis. The surface of the starch granule plays a fundamental role as the first barrier to processes such as granule hydration, enzyme attack, and chemical reaction with modifying agents. Major parameters describing the solid surface are: specific surface area, total pore volume, mean pore radius (diameter) and pore volume distribution in relation to pore radius (diameter).