Characterization of the surface morphology of durum wheat starch granules using atomic force microscopy

Knowledge of the structure and properties of microscopic surfaces of durum wheat starch granules is essential for understanding the functional and physico-chemical properties. The nanoscale surface undulations on the starch granules inside durum wheat macroscopically influence the milling properties. The objective of this study was to visualize the surface morphology and the size of starch grains of vitreous and nonvitreous durum wheat kernels using atomic force microscopy. The distribution of starch granules in the vitreous and nonvitreous durum wheat starch samples were examined and compared. The results of our study confirm the 'blocklet' model of the ultrastructure of the starch granule surface. Image contrast enhancement using UV/ozone treatment of microtomed starch samples improved the imaging of growth rings on the starch samples. The observation of growth rings in the nonvitreous starch granule surfaces indicates that amylopectin is more common than amylose in nonvitreous starch when compared with vitreous starch.