Plain, Parboiled and Instant

• Plain rice consists largely of starch, surrounded by a darker, fibrous layer of bran. Brown rice and other colored rices leave this bran on, making the rice more nutritious, but they take longer to cook as a result. White rice has the bran milled away, reducing its usual cooking time to 20 or 25 minutes but removing nutrients. Parboiled or "converted" rice par-cooks the grain in its bran, preserving many of the nutrients, then mills away the bran. Instant rice, the most processed of them all, is fully cooked and then dried.

The Gel Point

• Most starches can absorb a limited amount of moisture when they're uncooked, but it takes heat to make them easily digestible. At a certain temperature -- usually between 125 and 150 degrees Fahrenheit -- starch molecules expand vigorously and trap moisture into a gel. That's how starches dissolved in liquid thicken sauces, and how hard grains, such as rice, arrive at their cooked texture. Like quick-mixing gravy flour, instant rice is heated to this point so it only need to be moistened and heated before eating. To make this even faster and more convenient, the rice is subjected to stresses that open up tiny fissures in the grain. When it comes in contact with moisture, it acts almost like a sponge.

Soup In an Instant

• Regular rice is problematic as a soup ingredient. You can either precook it and add it at the last moment, with no opportunity to soak up the soup's flavors, or add it an hour or more before serving so it has time to cook. With instant rice, there's no need to precook the grain. Add it to the soup at least five minutes before serving, and it will absorb as much moisture as necessary from the broth. This gives it an advantage over precooked regular rice, because the instant rice will be fully infused with flavor of the soup.

Precooking Anyway

• Even though it isn't really necessary, from time to time you might precook your instant rice before adding it to soup. Sometimes that's a pragmatic choice; if you have leftover cooked rice you might as well use it. Some recipes might also recommend cooking the rice separately in water or broth, so it doesn't mute the taste of your broth. Rice's starch is a component in some soups, giving the broth a body it would otherwise lack. To simulate that effect with instant rice, puree some precooked rice with a portion of the broth and stir it back in. After 10 to 15 minutes, when it's had a chance to thicken slightly, add the rest of your rice.