Impact of durum wheat protein content on spaghetti in vitro starch digestion and technological properties

Grain protein content >12–13% is known to be an important factor in ensuring a good pasta quality. However, the impacts of a wide protein variation on starch digestion in the pasta are not well elucidated. In this study semolina blends were prepared to achieve a protein range of 8.9–18.8%. Dough strength was not effected but water requirements for pasta making increased as protein increased. Increasing protein content caused spaghetti cooked firmness to increase and water absorption and cooking loss to decrease linearly, these being beneficial to quality. However, spaghetti became duller with more red tones at higher protein content. As protein content increased, the extent of starch digestion decreased. Microscopy analysis suggests a more extensive and cohesive network forms at higher protein that could limit access by α-amylase and reduce starch granule gelatinization which could account for reduced digestion.