Retrogradation properties of rice starch gelatinized by heat and high hydrostatic pressure (HHP)

Retrogradation process of pressure-gelatinized rice starches was investigated and compared with the heat-gelatinized ones in this study. Our results showed that the retrogradation rate of normal rice starch gelatinized by high hydrostatic pressure (HHP) was slower than that by heat. Nevertheless, there was no difference in retrogradation rate for waxy rice starch gelatinized by the two treatments (P > 0.05). The DSC data were further analyzed using the Avrami equation. The result indicated that the pressure-gelatinized normal rice starch had a lower recrystallization rate (k) and a higher Avrami exponent (n) than the heat-gelatinized one, but the two treatments did not affect the k and n for waxy rice starch. Furthermore, the intact starch granules and lower amylose leaching were observed only in the pressure-gelatinized normal rice starch. These findings suggest that the retardation mechanism of HHP on starch retrogradation is probably attributed to less broken granules and lower leached amylose.

► Retrogradation process of rice starch gels obtained by high hydrostatic pressure.
► Comparison of retrogradation process of pressurized and heated rice starches.
► Retardation mechanism of high hydrostatic pressure on rice starch retrogradation.