People divide rice into sticky and non-sticky categories according to its viscosity after cooking. Glutinous rice is called japonica rice, non-sticky rice is called indica rice, and later glutinous rice is called glutinous rice. This difference in viscosity is mainly due to the different starch conditions of the three kinds of rice. Reagent detection: Cut off the rice grains, dip a little "iodine-potassium iodide" solution (rice flour extract can also be used) in the cross section, and see the color reaction: glutinous rice is brownish red, and indica rice or japonica rice is purplish blue. Transparent indica rice and japonica rice are translucent, while glutinous rice is opaque and looks milky white like wax. There is a kind of glutinous rice called Yinnuo, which is also like japonica rice or indica rice. It is translucent, but once it is dried, it becomes milky white and opaque. Therefore, opaque glutinous rice is called "waxy" rice abroad, and translucent indica rice and japonica rice are called "non-waxy" rice. There are differences in shape between indica rice and japonica rice, but there is not much difference between indica rice and japonica rice and glutinous rice. Indica rice is long and narrow, generally flat; Japonica rice is shorter, wider and rounder; The shape of glutinous rice, some like indica rice, some like japonica rice. Bibulous indica rice has the highest water absorption rate, followed by japonica rice and glutinous rice. So when cooking, add more water to indica rice, less water to japonica rice and less water to glutinous rice. Expanded indica rice is the largest, japonica rice is the smallest and glutinous rice is the smallest.