Dextrinisation is the breakdown of starch into shorter fragments called dextrins — and it sits at the heart of the Maillard reaction’s flavour chemistry. When starch is heated dry, as in toasting bread, roasting coffee, or baking a crust, the long amylose and amylopectin chains snap into smaller pieces. These dextrins brown more readily, taste sweeter, and dissolve more easily than the original starch, which is why a toasted crust is sweeter, browner, and crisper than the crumb beneath. The same chemistry drives the production of commercial dextrins: starch roasted with acid becomes the soluble fibre and fat-replacer used in processed foods. Dextrinisation is one of the fundamental heat transformations of cooking — the reason dry heat turns starchy foods golden, sweet, and aromatic.