Parboiled rice: Understanding from a materials science approach

•Parboiling of rice increases its nutritional and milling quality.•Improvement in colour and texture are needed to make parboiled rice more preferred.•The rice kernel undergoes significant material change during parboiling process.•The diffusion is the key parameter that affects the material property change.•Understanding of material change process can be used to tailor the final quality. The material properties like glass transition temperature, diffusion, microstructures of rice kernels and gelatinisation and retrogradation of the rice starch are reviewed to understand the nature and quality of the parboiled rice. Details of the diffusion related material properties of rice kernels such as the rate of diffusion, different models of diffusion, diffusion in glassy and rubbery state and diffusion in the gelatinised starch are discussed. The influences of hydrothermal treatment on the properties of the rice kernel are also highlighted to understand the overall quality of parboiled rice.