Effect of germination and parboiling treatment on distribution of water molecular, physicochemical profiles and microstructure of rice

The effect of germination and parboiling treatment on distribution of water molecular, physicochemical profiles and microstructure of rice was investigated. The results showed that the water molecular was evenly distributed in rice kernel after germination, but after subjecting to parboiling treatment, mobile water molecular might be confined to small region, which diffused from the outer regions into the rice kernel core. The reason may be that parboiling treatment produced macromolecular matrix where dispersed amylose chains form double-helical associations between starch granules so that water molecular is restrained and not entrapped within the starch crystallites. Meanwhile, the changes of microstructure and distribution of water molecular may be attributed to softness of germinated rice and hardness of parboiling rice. In addition, parboiling treatment had significant (p < 0.05) effect on the physicochemical properties of germinated rice. The viscosity and pasting temperature significantly (p < 0.05) increased. The storage modulus (G′), loss modulus (G′′), tan δ and shear stress had lower value compared to untreated germinated rice. Colour difference significantly (p < 0.05) increased, the microstructure of surface became smoother and compacter.