Mincing chilis breaks down cell walls, releasing capsaicin, the compound responsible for the chili's heat, more effectively than larger cuts. This results in a more intense and evenly distributed heat throughout the dish.
Chili peppers contain capsaicin, the chemical compound that gives them their spicy heat. Capsaicin is stored within the cell walls of the chili. When you mince a chili, you are essentially rupturing a large number of these cells. This rupture releases the capsaicin, making it more readily available to interact with your taste receptors. Larger cuts of chili, like slices or chunks, leave many of these cells intact, meaning less capsaicin is released during cooking or consumption. Mincing also helps to distribute the heat more evenly throughout the dish. The smaller the pieces, the more surface area is exposed, allowing the capsaicin to infuse into the surrounding ingredients. This prevents some bites from being overwhelmingly spicy while others are bland.
When handling hot chilis, wear gloves to prevent capsaicin from irritating your skin. Avoid touching your eyes or face after handling chilis, even if you've washed your hands, as residual capsaicin can still cause burning.