Ever wonder how rice become so fluffy after cooking it? It is due to the process involved during rice cooking which is gelatinization. Before going into the details, here’s a brief introduction of starches. Starch consist of two glucose polymer: Amylose and Amylopectin. Amylopectin is a highly branched molecule that makes rice sticky during cooking. Amylose is a long, straight starch molecule that does not gelatinize during cooking.
During cooking, the heat energy causes the bonds between amylose and amylopectin to break and the branches within amylopectin to break. This process makes it easier for water to enter the starch granules. As more water enter, the starch granules expands and it break. As it breaks, the amylose molecules will migrate out of the starch granules into the surrounding water while the amylopectin remains in the starch. At this stage, the starch granules have been gelatinized. The leaching of amylose into the surrounding causes the amylose content to decrease which will increase the glycemic index (GI) of the rice as they are inversely proportion to each other.
It is common to use 1 cup of water to cook 1 cup of white rice, but what about brown rice or unpolished rice? Because of its unrefined outer layer, cooking unpolished rice requires more water to cook than polish rice. How much is too much water? Three different amounts of water are used to cook 1 cup of unpolished rice and red basmati each.