Effect of flour type and dough rheological properties on cookie spread measured dynamically during baking

In order to monitor changes that occurred in cookie diameter during baking, a method of calculating cookie diameter was developed using Image Tools software. Cookie images were taken at 30-s intervals during baking using a digital camera. Six biscuit flour types were used in the trial. After the first minutes of baking, a rapid period of expansion started which was significantly different for flour types and finally, after approximately 6th min to the end of baking, cookies showed a slight shrinkage in diameter. A high and significant correlation was found between cookie spread rate and cookie final diameter (r = +0.73, P < 0.001). The technique of lubricated uniaxial compression showed all doughs made from different biscuit flour indicated pseudo-plastic rheological behaviour. However, the measured extensional properties did not correlate with the cookie final diameter.