Porous waxy maize starch: Thermal, structural and viscographic properties of modified granules obtained by enzyme treatment

Starch is the most important storage reserve carbohydrate in plants, and it has wide uses in the industry. It is also the main energy-providing source in human nutrition. Waxy starch, in turn, is virtually composed by amylopectin, with very low levels of amylose. This corn starch variety was partially hydrolyzed in order to verify the granules behavior and to study thermal phase transitions by thermal analysis, such as differential scanning calorimetry and simultaneous thermogravimetry–differential thermal analysis. Morphological and structural studies were performed, such as scanning electron microscopy and X-ray diffractometry. It was verified that treated samples showed low variation of enthalpy levels and also a slight increase in gelatinization temperature, possibly due to higher granule resistance to degradation. X-ray diffractometry analysis is within that expected, showing pattern A-type. Treated samples showed low viscosity peak and tendency to retrogradation when compared to its native counterpart.