Why do cereal grains expand upon cooking?

1. Starch Gelatinization:

* Structure: Cereal grains primarily consist of starch granules, which are composed of long chains of glucose molecules. These molecules are tightly packed in a crystalline structure, making the grain hard and dense.

* Water Absorption: When exposed to heat and water, the starch granules absorb water. This absorption breaks down the crystalline structure and allows the starch molecules to move freely.

* Gelatinization: The heat further disrupts the starch structure, causing it to swell and gelatinize. This process creates a gel-like substance, increasing the volume of the grain.

2. Protein Denaturation:

* Structure: Cereal grains also contain proteins, which are folded into specific shapes.

* Heat and Water: When exposed to heat and water, the protein structure unravels, a process known as denaturation. This process changes the protein's properties, making it more pliable and contributing to the overall expansion of the grain.

3. Water Absorption by other Components:

* Cell Walls: Cereal grains contain cell walls, primarily composed of cellulose. These walls also absorb water, adding to the overall expansion.

* Other Components: Other components within the grain, such as fiber and minerals, can also absorb water, contributing to the overall volume increase.

4. Gas Expansion:

* Yeast: Some cereal grains, like wheat, contain gluten proteins that can trap air bubbles during cooking, contributing to the expansion.

* Other Leavening Agents: Some recipes may include additional leavening agents like baking powder or baking soda, which also create gas bubbles and increase volume.

In summary, the expansion of cereal grains upon cooking is primarily due to the gelatinization of starch, denaturation of proteins, and water absorption by various components. This process results in a softer, more digestible, and often larger volume of cooked grain.