Typically, leftover rice is used to make fried rice. Chilled leftover white rice undergoes a process called retrogradation, in which the starch molecules form crystalline structures that make the grains firm enough to withstand the second round of cooking. Whereas freshly cooked rice becomes mushy, chilled leftover rice holds up well to stir-frying. However, the rice-cooker method of making tofu fried rice uses raw rice. No leftover rice is required.