Thermal Transition Properties of Spaghetti Measured by Differential Scanning Calorimetry (DSC) and Thermal Mechanical Compression Test (TMCT)

Glass transition temperature (T _g) of spaghetti sample was measured by thermal and rheological methods as a function of water content from 0 to 70 kg/100 kg spaghetti. In the cases of sample containing un-freezable water (i.e., amount of water which did not form ice even at very low temperature), calorimetric measurements performed by differential scanning calorimetry showed that the T _g values decreased from 142.8 to 42.7 °C when water content increased from 0 to 13.95 kg/100 kg spaghetti, respectively. Glass transition temperature increased with the increase of heating rate (2-50 °C/min) and reached to a nearly constant value above 30 °C/min. Thermal mechanical compression test showed relatively lower T _g values compared to the DSC values at low moisture contents, whereas at high moisture content T _g showed higher values. In the cases of samples containing freezable water (27-70 kg/100 kg spaghetti), glass transition shifts were merged with the ice melting endotherm. The freezing point, measured from the endothermic peak, decreased with the decrease of water content. In the state diagram, maximal freeze-concentration condition was determined as X′ _s = 0.81 kg/kg spaghetti from the intersection of the extended freezing curve and a horizontal line passing thru T′ _m = -10.3 °C.