Sugar Does More Than Sweeten

Sugar plays four roles in baking that have nothing to do with taste. It absorbs water, which keeps cakes moist. It interferes with gluten formation, making textures tender. It lowers the freezing point of ice cream. It also helps browning through caramelization and Maillard reactions.

Reduce sugar in a cookie recipe and you do not just make it less sweet — you change its texture, color, spread, and shelf life. Brown sugar contains molasses, which is acidic. Swap it for white sugar and you change the acid-base balance, affecting how baking soda reacts.