Glucono delta lactone (GDL) is a neutral cyclic ester of gluconic acid, produced with the acid by fermentation of glucose. It is commonly used as a mild or controlled release acidulant, as well as a leavening agent, chelating agent, curring accelerator or preservative agent enhancer. As a natural food acid it contributes to the tangy flavor of various foods and since it lowers the pH it also helps preserve the food from deterioration by enzymes and microorganisms.