Glucono-delta-Lactone

Glucono delta-lactone (GDL) is a naturallyoccurring food additive with the E number E575used as a sequestrant, an acidifier, or a curing, pickling, or leavening agent. It is a lactone (cyclic ester) of D-gluconic acid. Pure GDL is a white odorless crystalline powder.
GDL is commonly found in honey, fruit juices, personal lubricants, and wine[citation needed]. GDL is neutral, but hydrolyses in water to gluconic acid which is acidic, adding a tangy taste to foods, though it has roughly a third of the sourness of citric acid. It is metabolized to glucose; one gram of GDL yields roughly the same amount of metabolic energy as one gram of sugar. http://www.ytfoodchem.com/