Improving the rheological and thermal properties of wheat dough by the addition of γ-polyglutamic acid

The rheological and thermal properties of wheat dough with the addition of γ-polyglutamic acid (PGA) (0.5, 1.0, 5.0 g kg−1, w/w) was evaluated by the measurements of farinography, rapid visco analysis and differential scanning calorimetry. Adding 5.0 g kg−1 PGA in wheat dough increased the mixing stability and raised the pasting temperature from 75.8 to 84.4 °C, but decreased the peak viscosity and breakdown. The water holding capacity of wheat dough increased with the addition of 5.0 g kg−1 of PGA. At 5.0 g kg−1 level, PGA caused significant declines in the enthalpy, onset and peak temperatures of ice-melting transition of wheat dough. Scanning electron microscopy showed that wheat bread with the addition of 1.0 and 5.0 g kg−1 PGA exhibited microstructures with smoother surfaces. During storage, PGA retarded the staling process of wheat bread.