Parboiled rice is the rice type specifically steam-treated before being ground. Steaming was developed in the USA more than 50 years ago. The US military men were the idea generators of such a rice treatment process as parboiled rice is easy to cook and it retains its properties and taste after heating.
Due to steaming almost all vitamins and mineral elements come from grain capsules into grains themselves! What is crucial that parboiled rice is always crumbly and whole without losing its properties even being reheated.