Influence of enzyme treatment on the rheology of rye doughs

Abstract

The rheological behaviour of rye dough is mainly influenced by enzymatic reactions. An investigation with a rotation rheometer called a rheological baking test was used to study the influence of pentosanase, proteinase, fungal α-amylase, and bacterial α-amylase, respectively. The application of pentosanase increased the plasticity of the dough and decreased the viscosity. Proteinase had only a slight influence on the rheological behaviour of rye dough. It slightly decreased the dough viscosity, but had no influence on the visco-elasticity. The fungal and the bacterial α-amylase showed the same effects. The dough elasticity decreased with the increase in temperature. These effects are obvious even at temperatures below gelatinization, and the bacterial amylase shows a greater influence, because it can work at higher temperatures. It could be concluded that the dough structure is mainly built up by pentosans and proteins at temperatures of 30°C, whereas the starch plays a major role in the temperature range above 45°C. A bread baking test showed that pentosanase had an effect on the shape of the loaf whereas the amylases influenced the volume and the crumb elasticity. Proteinase showed no influence on baking results. This correponds well with the results of the rheological investigations. The rheological baking test is a good tool for predicting the baking performance of rye flour.