Rheological properties of water insoluble date fiber incorporated wheat flour dough

The influence of water insoluble date fiber addition, to standard flour was studied through theological tests at small and large deformations and at different levels of fiber incorporation (1-10 g/100 g). The added DF increased the water absorption of the dough. An increase in mixing time and stability were recorded upon addition of DF (<= 5 g/100 g), and the extensibility decreased at similar condition. The elastic modulus, G' of the blended doughs increased with fiber concentration in the frequency range of 0.1-10 Hz, and the dough exhibited predominating solid-like behavior. The difference in microstructure between control and fiber incorporated dough samples were characterized by a plot of G' vs. G ''. During non-isothermal heating of doughs from 30 to 95 degrees C at a heating rate of 2.5 degrees C/min, the G' achieved its peak value (T-G'max) at a temperature representing the peak gelatinization temperature (T-p). Addition of DF did not significantly affect the T-p of the dough. The dough gelatinization kinetics was described by two rate equations corresponding to upward and downward of gelatinization curve. The upward and downward curves fitted the first-order and the second-order reaction kinetics, respectively. The gelatinization process activation energies ranged between 129 and 194 kJ mol(-1). (C) 2012 Elsevier Ltd. All rights reserved.