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

Xia, Wen, Liu, Chengmei, Luo, Shunjing, Xu, Xingfeng, Fu, Guiming
Die Stärke = 2015 v.67 no.11-12 pp. 1044-1052
Fourier transform infrared spectroscopy, X-ray diffraction, adhesion, crystal structure, differential scanning calorimetry, gels, hardness, industry, milling, retrogradation, rice, scanning electron microscopy, temperature, texture
The retrogradation properties of rice gels with different milling degrees (0, 3, 6, and 9%) stored at 4°C and −20°C were investigated. Results showed that rice gels with the same degrees of milling (DOM) stored at 4°C retrograde faster than those stored at −20°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°C. Differential scanning calorimetry (DSC) revealed that the higher the milling degree, the higher retrogradation index (ΔHr/ΔHg) obtained at 4°C or −20°C. X‐Ray diffraction (XRD) analysis indicated that samples stored at −20°C had a lower degree of crystallinity compared with those stored at 4°C, which was also confirmed by Fourier Transform infrared spectroscopy (FTIR) analysis. Scanning electron microscopy (SEM) analysis showed that samples stored at −20°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.