Rice is the staple diet of more than 50% of population of world. In India, most of the people depend on rice as food. India is one of the most important countries in production of varieties of paddy. It is a good source of carbohydrate and contains about 8-9% of good quality protein. It also contain some B vitamins.
Rice is extracted from paddy after milling. Too much milling or polishing removes most of nutritional value. Washing with a lot of water; cooking in more than required amount of water and draining the water removes much of vitamins from it. Thiamine is a important B vitamin, it contains. In it’s deficiency, people suffer from beriberi. Beriberi is marked by soreness in tongue, anemia, swelling of body due to involvement of circulatory system; and blunting of sensory and motor nervous system etc. Rice consists of three parts namely; germ,endosperm and the outer layer called pericap. The endosperm contains most of carbohydrate where as germ and pericap contain most of vitamins.
Parboiling is an age old established process of preserving the nutritional value of rice in India. This is done in tree steps; 1) soaking paddy in water heated upto about 65 degrees Celsius temperature for 4-5 hours and draining the water; 2) steaming as such; and 3) drying under sun. This process hardens the outer layer of rice making it resistant to insects; the vitamins and nutrients percolate into the deeper layer making those relatively non removable to milling and making it easily digestible by gelatining the starch. Thus, parboiling helps it in many ways in preserving the nutritional value. Rice should not be washed in copious amount of water for many times making the water soluble vitamins vulnerable to be washed away. It also should not be cooked in a large amount of water, and water be drained;which will take away nutrients with it.
So, parboiling and cooking in just the amount of water will protect the nutritional value.