New approaches for semolina characterization

Semolina from durum wheat is considered the most suitable raw material for pasta-making. Protein quantity and quality are important factors affecting pasta properties, while the role of starch has received less attention. In this study two semolina samples (organic and conventional), different in protein and starch characteristics, were analyzed using both conventional and new approaches. Starch organization was studied by using DSC, MVA test, and X-ray diffraction. Rheological properties of dough during heating and cooling were investigated using Mixolab ® and Farinograph ®. Despite a lower protein and gluten content, the dough from organic semolina was stronger than conventional semolina. The organic semolina was characterized by a higher total starch content, with a higher pasting viscosity, larger gelatinization temperature range, and a higher  H value. Exposure of semolina to iodine vapour exhibited differences in the organization of the starch granules. Both the new approaches used to investigate dough behaviour under heating and cooling showed similar trends. More differences between the semolina samples appeared during the heating and cooling steps: the organic semolina showed a higher consistency than conventional semolina. These preliminary results suggest that there are differences in the starch properties between semolina that require further studies.