The differential influence of dry heat treatment on pasting, thermal, morphological, and crystalline structural properties of glutinous rice starch (GRS) and glutinous rice flour (GRF) in a dry state for 0, 2, or 4 h at 130°C were studied. The results revealed that the viscosity and thermal stability of GRS and GRF increased after dry heat treatment. Peak viscosity of GRF rose nearly threefold from 1156 to 3145 cP. The number of disulphide bonds in GRF increased from 1.93 to 3.19 mmol/g, indicating the covalent SS linkages after dry heat treatment may result in the changes of protein structure, which may greatly influence properties of dry heated flour. Morphology of gelatinized GRS was denser, and a strong laminar structure was observed for gelatinized GRF after dry heat treatment. Fourier transformation infrared spectroscopy indicated that both GRS and GRF had relatively higher transmittance intensities in the region of 1068 and 1022 cm À1 . X-ray diffraction showed that the crystallinity of GRS increased from 32.82 to 35.02% and GRF increased from 29.32 to 34.14% after dry heat treatment. Dry heat treatment had greater effects on viscosity and structural properties of GRF than those of GRS.

Glutinous rice flour (GRF) and glutinous rice starch (GRS) were modified by dry-heat treatment and their rheological, thermal properties and freeze-thaw stability were evaluated. Compared with the native GRF and GRS, the water-holding ability of modified GRF and GRS were enhanced. Both the onset and peak temperatures of the modified samples increased while the endothermic enthalpy change decreased significantly (p < 0.05). Meanwhile, dry heating remarkably increased the apparent viscosities of both GRF and GRS. Importantly, compared with GRS samples, the storage modulus (G') and loss modulus (G") values of modified GRF increased more greatly and the tanδ values decreased more remarkably, indicating that the dry-heat treatment showed more impact on the GRF and a higher viscoelasticity compared with GRS. Our results suggest the dry-heat treatment of GRF is a more effective method than that of GRS, which omits the complex and tedious process for purifying GRS, and thereby has more practical applications in the food industry.