A Continuous Measurement of Swelling of Rice Starch During Heating
Abstract The changes in size distribution of rice starch granules during heating have been determined continuously using a polarised light microscope in combination with a hot stage and an image analysis system. The size of starch granules increased slightly as the temperature was raised from 35°C to 55°C, with a 3·9% increase in average area; however, a dramatic increase in size of starch granules occurred at 65°C. The swelling of the starch granules reached a maximum 54·7% increase in average area at 75°C which is coincidental with the peak temperature ( T p ) of DSC thermograms. Starch granules proceeded to disrupt/dissolve above 75°C. Loss of birefringence occurred at a lower temperature than granule rupture. T p appeared to be the critical point in the phase change between the stages of swelling and disruption/dissolution of rice starch granules during heating.