Insight into protein-starch ratio on the gelatinization and retrogradation characteristics of reconstituted rice flour.

Protein and starch are the two most abundant components in rice flour and play an important role in its physicochemical properties. Herein, the gelatinization and retrogradation properties of reconstituted rice flour (RCRF) composed of different protein-starch mass ratios were investigated. It was found that increasing the protein content from 0% to 8% will result in the gelatinization peak viscosity of the RCRF being reduced from 2198 ± 96.8 cp to 1754 ± 111.6 cp, the gelatinization temperature increased from 72.4 ± 0.4 °C to 75.6 ± 1.8 °C. In addition, the hardness of RCRF gels was increased after retrogradation, while a reduction in crystallinity was found depending on the increasing of protein content during storage. The increase of protein content could lead to the insufficient gelatinization of the RCRF, inhibiting the long-term retrogradation of flour. On the other hand, the water migration in the RCRF gels could be weakened with the protein addition, as well as the water distribution was more uniform and the gel shape could be moderately maintained. These results indicated that changes in protein-starch mass ratio have an important effect on the properties of the RCRF, especially gelatinization and retrogradation characteristics.