On food and cooking the science and lore of the kitchen ( PDFDrive ) 873

granules are almost pure amylopectin The Proportions of Proteins in Seeds 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– 160ºF/60–70ºC (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 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 the looser clusters of amylopectin molecules This is why long-grain Chinese rices are made with more water than short-grain Japanese rices Cooling Reorganizes Starch Molecules and Firms Granules Once the cooking is finished and the seeds cool down below the gelation temperature, the starch molecules begin to reform some clusters with pockets of water in between, and the soft, gelated starch granules begin to firm up again This process is called retrogradation The simpler amylose molecules start bonding to each other again almost immediately, and finish within a few hours at room or refrigerator temperatures Sprawling, bushy amylopectin molecules take a day or more to reassociate, and form ... Firms Granules Once the cooking is finished and the seeds cool down below the gelation temperature, the starch molecules begin to reform some clusters with pockets of water in between, and the soft, gelated starch granules begin to firm up again... This is why long-grain Chinese rices are made with more water than short-grain Japanese rices Cooling Reorganizes Starch Molecules and Firms Granules Once the cooking is finished and the seeds cool...gelatin.) The tightly ordered clusters of amylose molecules require higher temperatures, more water, and more cooking time to be pulled and kept apart than the looser clusters of amylopectin