Hearth bread baking quality of durum wheat varying in protein composition and physical dough properties

Thirty durum wheat genotypes from ten countries of origin were grown in field plots for two consecutive years. Three of the genotypes were γ-gliadin 42 types and the remainder were γ-gliadin 45 types. Among the γ-gliadin 45 types, six high-molecular-weight glutenin subunit (HMW-GS) patterns were identified: 6 + 8, 7 + 8, 7 + 16, 14 + 15, 20 and 2*, 20. All the γ-gliadin 42 genotypes contained low amounts of unextractable polymeric protein (UPP) and exhibited low gluten index values and weak gluten properties. The γ-gliadin 45 genotypes exhibited a wide range of UPP, gluten index and dough strength. HMW-GS 20 genotypes were generally weak, whereas HMW-GS 6 + 8 and 7 + 8 genotypes were generally strong. When baked by a lean formulation, long-fermentation straight-dough hearth bread process, the durum wheat genotypes exhibited a wide range of baking quality. Loaf volume and bread attributes were strongly correlated with UPP and gluten index. Some of the genotypes exhibited bread attributes and loaf volume equal or slightly superior to those of a high-quality bread wheat flour. However, even the strongest durum wheat genotypes exhibited inferior fermentation tolerance to the bread wheat flour, as seen by a requirement for lower baking absorption during dough handling and more fragile dough properties when entering the oven. Among the HMW-GS groups, HMW-GS 7 + 8 and 6 + 8 exhibited the best and HMW-GS 20 the poorest baking quality. Farinograph, alveograph and small-scale extensigraph properties demonstrated that a combination of dough elasticity and extensibility was needed for superior durum wheat baking performance. © 2007 Society of Chemical Industry.