GDL, also known as gluconolactone, is a food additive with the E number E575, used as a sequestrant, an acidifier, or a curing, pickling, or leavening agent. It is a lactone of d-gluconic acid. Pure GDL is a white odorless crystalline powder.
GDL has been marketed for use in feta cheese and meat processing. GDL is neutral, but hydrolyses in water to gluconic acid, which is acidic, adding a tangy taste to foods.