Physical and mechanical properties of bread loaves produced by incorporation of two types of toasted durum wheat flour

The aim was to study the effects of toasting of durum wheat kernels on the physical ana mechanical properties of bread containing increasing amounts of toasted wholemeal. Two toasting procedures were considered: heating of the kernels arranged on tin cans (TDW1) and the stubble burning (TDW2). The addition of toasted flour determined a decrease in volume (greater when TDW2 was used) and detrimental effects on mechanical properties caused by the thermal denaturation of the gluten-forming proteins and the interference of bran. Volume was negatively correlated with compressibility, gumminess, masticability and positively correlated with elasticity (0.824 < R < 0.971). The bread structural parameters were quantified by digital image analysis and correlated to the variations of the mechanical properties. The addition of increasing percentages of toasted wheat flour (especially, TDW1) determined significant increases of the cell density, and decreases of cell mean area, and cell equivalent diameter. Statistically significant correlations were obtained between cell density or equivalent diameter and the mechanical properties of all the bread types according to a second order polynomial regression but only the former allowed to predict approximately 60% of the variation of crumb compressibility and 87% of the variation of elasticity and gumminess both in bread produced with TDW1 and in bread produced with TDW2. (C) 2009 Elsevier Ltd. All rights reserved.