2.2. Differential scanning calorimetry
The thermal properties of rice flour ground from aged rice grain
were determined with a differential scanning calorimeter (DSC)
Model 821 (Mettler-Toledo Ltd., Australia). Rice flour (4.0–
4.1 mg) was weighed into an aluminium pan and distilled water
containing sodium azide (0.02% w/w) was added using a microsyringe
to give a water-to-flour (dry solid) ratio of 2.5:1 (w/w). The
sealed sample was equilibrated for 5 h and then heated from 30
to 110 C at a heating rate of 7 C min1 to determine the gelatinization
enthalpy and temperatures. Sodium azide was added to
samples to inhibit growth of microorganisms during the 5 h incubation.
Sodium azide solution (0.02% w/w) was used as a reference.