Lecithin

A natural food additive extracted from soybeans that acts as an emulsifier and surface active agent. In chocolate manufacture, lecithin helps control flow properties in chocolate by reducing its viscosity. As an emulsifier, it helps maintain an emulsion (attachment) between the cocoa butter and the sugar. If no lecithin is added, the resulting chocolate is thick and dense and tends to keep air inside the bar, which can create a rough surface texture.