Effects of temperature and mechanical input on semisweet biscuit (cookie) quality and dough characteristics

The effects of specific mechanical energy (SME) and dough temperature at th e end of mixing (T-f) on semisweet biscuit dough characteristics and biscui t quality were studied using an experimental mixer fitted with monitoring d evices. The fluid circulating in the double jacket of the mixing bowl was r egulated at variable temperatures and mixed dough samples were prepared at T-f of 23, 30, and 37 degrees C for three levels of SME input (20, 60 and 1 20 kJ/kg). Correlation analysis showed that semisweet biscuit length and th ickness were independent quality parameters, influenced respectively by the T-f of dough and SME. Biscuit thickness and volume increased with SME inpu t, but SME had no significant influence on the physicochemical characterist ics of the dough. Biscuit length was related to the density and stickiness of the dough and to rheological behavior as assessed by fundamental and emp irical measurements. A rise in dough temperature >35 degrees C induced a dr amatic increase in viscoelastic properties, leading to biscuit shrinkage. T he increase of dough density with T-f seemed to be related to the melting o f solid fat in the dough recipe. Melting of fat during mixing could also be a source of viscoelastic changes in the dough at T-f.