Dextrinisation

Dextrinisation is a chemical process that involves the breakdown of starch into smaller carbohydrate units called dextrins. This process is typically initiated by heating. When starch granules are heated, especially in the presence of dry heat or with limited moisture, they absorb water and swell. As the temperature increases, the long chains of glucose molecules within the starch begin to break apart, forming shorter chains and individual glucose units. This breakdown is often accompanied by changes in texture, color, and flavor.

In cooking, dextrinisation plays a significant role in browning and flavor development. For instance, toasting bread or the crust of baked goods involves dextrinisation of the starches on the surface. The heat causes the starch to break down, leading to the formation of dextrins, which can then undergo Maillard reactions with amino acids, contributing to the characteristic brown color and complex flavors. Similarly, when thickening sauces or gravies, heating the flour-based roux initiates dextrinisation, altering the starch's ability to absorb water and create a smoother, more stable consistency. The extent of dextrinisation can influence the final properties; higher temperatures and longer heating times result in more extensive breakdown and a greater proportion of smaller dextrins. Enzymes can also catalyze dextrinisation, a process utilized in industries like brewing and baking to modify starch properties.