Impact of durum wheat grain composition on semolina yield and pasta quality

In Italy, France and Greece, traditional dried pasta are manufactured exclusively from durumwheat semolina and water. Thus, spaghetti quality is directly linked with the durum wheatgrain quality. This talk demonstrates how the durum wheat grain composition and physicalattributes affect semolina yield and composition and finally the pasta quality.Five durum wheat grain samples, grown in 2014 under different nitrogen doses, werecharacterized in terms of mass, texture and mechanical properties and biochemicalcomposition and transformed on a milling pilot plant (scale 150kg) delivering 18 differentfractions. Yield in the different flour and semolina fractions, as well as their biochemicalcomposition (content in protein, ash, phytic acid, damaged starch, total starch) and physicalattributes (particle size distribution) were determined and related to the grain characteristics.In particular semolina yield was found related to grain vitreousness and grain protein content.The different milling fractions were combined in order to compose eighteen differentsemolina blends, representing six levels of protein content (9.2 to 13.5%) , four levels of ashcontent (0.65 to 1.16%) and three particle size distributions (D50 from 230 to 600 μm). Eachvariable (protein, ash, D50) was tested at different levels, values of the other two being fixed.In this a way, an experimental design was constituted. The semolina blends were transformedinto pasta on an experimental press (scale 10 kg) and dried using standard low and hightemperature diagrams. Color and defaults (speck, spots and cracks) of the dried spaghettiquality were assessed. Cooking quality of pasta was evaluated by measuring pasta viscoelasticityafter optimal cooking time +6min.The study confirms that a high ash content decreases significantly the yellowness andthe brightness index of pasta. Semolina particle size distribution impacts also the pasta color,coarser semolina leading to brighter pasta. A significant positive effect of semolina proteincontent was shown on the viscoelastic index of pasta. This approach allows a non-distortedestimate of how each variable impacts the pasta quality.Marianne