Fundamental rheological properties of spontaneously-fermented ancient wheat sourdoughs

Abstract

The fundamental rheological behaviour of spontaneously-fermented wholegrain emmer, spelt and khorasan sourdoughs was studied from final backslopping over a 12‐hr fermentation period. Spontaneously-fermented sourdough was prepared through backslopping (every 24 h, 5 days) under laboratory conditions (temperature of 25 °C, dough yield of 200). Emmer, spelt and khorasan sourdoughs exhibited similar pH evolution, but they significantly differed in level of leavening (expressed as the increase in height between two backsloppings), gluten index values and dynamic viscoelastic properties. The pH of all sourdoughts decreased from 6.5 to 4.0 after four backslopping steps. Emmer flour which exhibited the lowest gluten quality (gluten index value) was characterized with the fastest and the highest level of leavening during sourdough propagation. Results of the dynamic oscillatory rheological analysis showed that there was a decrease in dough elasticity with fermentation time for all three sourdoughs, which could be ascribed to protein degradation and conformational changes due to proteolytic activity and acidic environment. Over the course of the fermentation period (12 hours) emmer sourdough was significantly less elastic and softer than the spelt and khorasan sourdoughs. It can be concluded that sourdough structure degrading processes was affected with the differences in gluten quality of ancient wheat.