The cohesiveness and tenderness of cooked rice depends largely on

The cohesiveness and tenderness of cooked rice depend largely on starch while starch is a mixture of two polymers amylose and amylopectin, so it ultimately depends upon the proportion of amylose and amylopectin present in the rice. Rice with high amylose content becomes firm and dry after cooking, whereas rice with medium amylose content makes the rice softer and stickier and low amylose content makes it quite soft and sticky.