system
Given the following post, respond as if you're commenting on Reddit:
human
Why does fresh prepared rice, nice soft rice, dry out when sealed immediately and refrigerated?
gpt
There are two kind of starch in rice: amylose and amylopectin. Amylose is a long, straight starch that rigidifies when it cools. Amylopectin is stockier and branched in structure, and it gelatinizes under heat.

 Long grain rice—the rice most prone to hardening in the fridge—has a high proportion of amylose. The shorter the grain, the less amylose and the more amylopectin—which is why shorter grains are used for risotto and sushi.

There's a Good Eats episode that does a good job of explaining this.