An uncooked rice grain (dry) absorbs less water than a parboiled rice grain at the room temperature. At temperatures near
to the gelatinisation temperature of the rice, the uncooked rice
grain absorbs more water than the parboiled rice (Pillaiyar and
Mohandoss, 1981a). This unusual property of the hydration of
the rice kernel has been explained from the viewpoint that water
diffusion property of the starch is governed by the extent of starch
gelatinisation and retrogradation, as well as the level of pores and
fissures present in the grain. However, a study on the rehydration
of freeze dried parboiled rice showed that a higher extent of gelatinisation increased the rate of rehydration (Puspitowati and Driscoll, 2007). This suggests that not only the extent of starch
gelatinisation but the microstructure that underlines the gelatinised nature of the kernel affects the rehydration phenomena of parboiled rice