Abstract
The gelatinization properties of 20 kinds of Indica and Japonica rice were measured by differential scanning calorimetry (DSC), the β-amylase-pullulanase method (BAP) and Fourier-transform infrared spectroscopy (FT-IR/ATR). There was a high correlation between the peak temperature for gelatinization and the apparent amylose content. The FT-IR peak at around 1000cm-1 increased in height with increased cooking time. The absorbance at this wavenumber reflects an increase in the amount of OH groups, which are hydrated due to gelatinization of starch. There was a high correlation in the degrees of gelatinization found by the FT-IR method and the BAP method. The calibration curve obtained in this study indicates that the measurement of the degree of gelatinization of cooked rice by FT-IR at around 1000cm-1 is an alternative to the conventional BAP method. It was also found that the hardness and stickiness of cooked rice as determined by sensory evaluation could be predicted based on the height of the FT-IR absorption peak.
