A couple of months ago, my husband went into our walk-in pantry and started examining the shelves. 'Why do you have so many types of rice?' he asked. 'Because I need them,' I replied. 'Why do you have two jars of the same rice?' he asked, pointing to two glass jars. I explained that although they looked similar, one type was Japanese rice - which I pack into the bento boxes I take to work - while the other was glutinous rice, used for nor mai fan (Chinese sticky rice with wind-dried sausages and dried shrimp).
I decided not to point out the other types of rice I keep in the pantry. There's jasmine rice for everyday eating; carnaroli for when I make risotto; Spanish rice for paella; and an as-yet unused pack of idli rice that I purchased because I hope one day to make those delicate Indian steamed breads that use fermented rice batter.
Not all rice is created equal, and most are not interchangeable. At a basic level, there's long-grain, medium-grain and short-grain rice. Many people say that the longer the grain, the less sticky the rice, and while that's true in general, there are exceptions. Types of long-grain rice are used in Indian biryani and Middle-Eastern pilafs, where the grains remain light, distinct and separate. But Spanish paella uses varieties of medium- and short-grain rice that also remain distinct, without sticking together. And some types of long-grain rice, such as jasmine, have grains that are slightly sticky and can be scooped up with chopsticks.
Jasmine rice isn't as sticky as the short-grained rice used in Japanese and Korean cuisines, which is starchier (although the rice is washed in several changes of water before being cooked, which removes the excess starch on the outside of the grain). Everyday Japanese and Korean rice is not the same as the even stickier glutinous rice used to make nor mai fan, zhong-zi [rice dumplings], rice cakes and mochi.
The Italian rice varieties used to make risotto are noted for their starchiness. Risotto uses a special cooking technique: the rice is not washed in advance (as it is with Asian cuisines), and it's cooked in the skillet with butter (or oil) and stirred to coat the grains with the fat. Then hot liquid is added to the pan in small increments and the ingredients are stirred constantly, which releases the starch in the grains as they absorb the liquid. When risotto is cooked properly, it has a rich, almost soupy texture, with firm grains of rice in a starchy liquid.