CHARACTERIZING IN-SITU STARCH GELATINIZATION - THERMAL AND DYNAMIC-MECHANICAL ANALYSIS OF DURUM-WHEAT DOUGH

Data obtained by dynamic mechanical analysis and DSC analysis of durum wheat dough are presented and discussed. Doughs with water contents r anging from 45 to 55% (w/w) were subjected to sinusoidal shearing by m eans of a dynamic mechanical spectrometer (Rheometrics, RFS2) equipped with parallel plate geometry, 0.1 strain amplitude and 1 rad/min freq uency. The tests were carried on in temperature sweep mode at a heatin g rate of 2 degrees C min(-1). Wheat samples with water contents in th e range between 7.5 and 37.5% and doughs with 37.5% moisture content w ere mixed for different times and subjected to DSC analysis (Perkin-El mer, DSC-7) at a heating rate of 20 degrees C min(-1). Dynamic mechani cal analysis revealed that the relationship between the dynamic proper ties of the dough and the temperature was modified as the water conten t of the dough increased and was quite different from that for gluten. A similar response was observed in the course of temperature scans ma de by means of DSC. These experimental findings suggest that the water -starch interaction in the presence of a protein matrix is affected by the availability of water and that the protein system is a competitor with respect to starch.