“Rice” is not one interchangeable ingredient. Grain shape, starch composition, processing and age all affect how much water it takes up and whether the cooked grains remain separate, cling together or release starch into a sauce.
Long, medium and short grain
Long-grain rice usually cooks into more separate grains. Medium- and short-grain types tend to be plumper and more cohesive. These are useful families, not exact cooking instructions: basmati, jasmine, bomba, arborio and sushi rice each have a specific behaviour and culinary use.
Amylose and amylopectin
Rice starch is largely made of amylose and amylopectin. Higher-amylose rice tends to cook firmer and more separate; waxy or glutinous rice is rich in amylopectin and becomes sticky. “Glutinous” describes texture and does not mean that the rice contains gluten.
Why rinsing changes the surface
Rinsing removes loose surface starch and handling dust. That helps separate grains in many pilafs, but a risotto method deliberately develops a creamy starch-rich liquid. Washing is not a universal virtue: follow the intended texture and the producer's directions.
Brown, white and parboiled
Brown rice retains bran and germ and normally needs more time. White rice has those layers removed. Parboiled rice is treated before milling so its texture and cooking behaviour differ from ordinary white rice. Do not transfer one water ratio blindly between them.
