Glucono-δ-lactone (GDL), also known as gluconolactone, is an organic compound with the formula (HOCH)3(HOCH2CH)CO2.

The conversion cogenerates hydrogen peroxide, which is often the key product of the enzyme: Gluconolactone spontaneously hydrolyzes to gluconic acid:[4] Gluconolactone is a food additive with the E-number E575[5] used as a sequestrant, an acidifier,[6] or a curing, pickling, or leavening agent.

The rate of hydrolysis of GDL is increased by heat and high pH.

[8] The yeast Maudiozyma bulderi can be used to ferment gluconolactone to ethanol and carbon dioxide.

[9] It is also a complete inhibitor of the enzyme amygdalin beta-glucosidase at concentrations of 1 mM.