Rheological characterization of dough and bread by using a dynamic mechanical analyzer

Research was conducted to characterize rheological properties of wheat flour dough and bread crumb using a dynamic mechanical analyzer (DMA) to establish their relationships with breadmaking performance and bread staling, respectively.; The DMA thermal expansion pattern of a flour-water dough during heating showed four stages with changes in the thermal expansion coefficient: gas thermal expansion (GTE) (25–60°C), starch gelatinization-gluten matrix formation (GMF) (60–100°C), vapor pressure expansion (VPE) (100–120°C), and structure fixation-crust formation (SCF) (>120°C). The thermal expansion coefficient (C_e2) of flour-water dough during GMF was highly correlated (r = 0.941) to bread loaf volume. The ratio (C_e2/C_e1) of thermal expansion coefficient during the GMF stage to the coefficient during the GTE stage also was significantly correlated (r = 0.939) to baking volume.; The recovery strain of flour-water dough with a fixed water absorption of 54% was highly correlated (r = 0.939) to bread loaf volume. Flours with a large bread volume exhibited greater dough recovery strain. The recovery strain of flour-water doughs was also correlated to some of the parameters provided by the mixograph, farinograph, and TA-XT2 extensigraph.; Typical viscoelastic behavior of bread crumb involved a transition from rubberlike to glasslike consistency with increasing dynamic frequency. At a low frequency region, the dynamic storage (E′) and loss (E″) moduli were relatively small and nearly constant, showing characteristics of the rubbery plateau. Then, they increased rapidly with increasing frequencies and approached a glasslike state. Tanδ was low and almost constant at low frequencies before the transition, then went through a prominent peak with increasing frequency. The frequency at which the tanδ of bread crumb started to rapidly increase was defined as the onset frequency (f_o) of the transition. The f_o increased with the aging of bread, which correlated highly to bread staling (r = 0.942). Both dynamic moduli E′ and E″ at f_o increased with bread aging, which correlated highly to firmness obtained using a TA-XT2 texture analyzer in a static compression mode (r = 0.941 and 0.943, respectively).