Effect of low temperature on the retrogradation behavior of rice gels with different milling degrees

摘要

The retrogradation properties of rice gels with different milling degrees (0, 3, 6, and 9%) stored at 4 degrees C and -20 degrees C were investigated. Results showed that rice gels with the same degrees of milling (DOM) stored at 4 degrees C retrograde faster than those stored at -20 degrees C. Moreover, higher milling degree leads to a faster retrogradation in the same temperature. Texture profile analysis demonstrated that samples showed a lower hardness but higher adhesiveness during storage at -20 degrees C. Differential scanning calorimetry (DSC) revealed that the higher the milling degree, the higher retrogradation index (Delta Hr/Delta Hg) obtained at 4 degrees C or -20 degrees C. X-Ray diffraction (XRD) analysis indicated that samples stored at -20 degrees C had a lower degree of crystallinity compared with those stored at 4 degrees C, which was also confirmed by Fourier Transform infrared spectroscopy (FTIR) analysis. Scanning electron microscopy (SEM) analysis showed that samples stored at -20 degrees C presented a more shrinkable appearance with more pores. The results are expected to provide some theoretical guidance for retarding the retrogradation of rice in processing and preservation industry.