Cooking & Baking

Cell Structure and Enzyme Release: Onions are composed of elongated plant cells that run from the root to the stem end. When you cut an onion pole to pole (along the grain), the knife slices parallel to the cell walls, rupturing fewer cells. This results in less release of enzymes like alliinase and LF synthase, which are stored in separate compartments within the cells. When these enzymes mix with sulfur-containing compounds like isoalliin, they trigger a chemical reaction that produces thiosulfinates—the pungent, tear-inducing molecules responsible for onion flavor.

Crosswise Cutting Increases Pungency: Cutting across the grain (perpendicular to the cell alignment) tears through the cell walls more aggressively. This ruptures more cells, releasing significantly more enzymes and sulfur compounds. The increased exposure leads to a greater formation of thiosulfinates, resulting in a stronger, more intense flavor and a sharper aroma. This is why minced or finely chopped onions taste more powerful than sliced ones.

Surface Area and Oxidation: The more you cut an onion, the greater the surface area exposed to oxygen. This accelerates the enzymatic reaction, further intensifying flavor. Finely diced or grated onions release flavor more quickly and completely, while larger, whole slices or rings retain more structure and milder taste.

Cooking and Flavor Transformation: Heat inactivates the enzymes, stopping the pungent reaction. Slow cooking (e.g., caramelizing) breaks down harsh sulfur compounds into sweet, complex flavors. However, the initial cut determines how much flavor is released during cooking—finer cuts yield more intense flavor upfront, while coarser cuts preserve texture and milder taste.

OMG... I love onions...



https://www.americastestkitchen.com/articles/5730-onion-flavor-depends-on-how-it-s-cut