Cooking Separates Starch Molecules and Softens Granules

When a seed is cooked in water, the starch granules absorb water molecules, and swell and soften as the water molecules intrude and separate the starch molecules from each other. This granule softening, or gelation, takes place in a temperature range that depends on the seed and starch, but is in the region of 140–160°F/60–70°C. (The conversion of solid starch into a starch-water gel is often referred to as “gelatinization,” but this is unnecessarily confusing; starch has nothing to do with gelatin.) The tightly ordered clusters of amylose molecules require higher temperatures, more water, and more cooking time to be pulled and kept apart than do the looser clusters of amylopectin molecules. This is why long-grain Chinese rices are made with more water than short-grain Japanese rices.