Glucono delta-lactone

Glucono delta-lactone (GDL) is the cyclic ester form of gluconic acid, produced commercially by the microbial fermentation of glucose. When dissolved in water it hydrolyses slowly to gluconic acid, releasing acidity in a controlled, time-delayed manner. This unique property makes it especially valuable in applications where instantaneous acidification would be disruptive: it is the key acidulant in silken tofu production, where it gels soy protein slowly and uniformly; it is also used in fermented meat products, baked goods, and dairy applications.

Like gluconic acid itself, GDL is a naturally occurring food component — it is found in honey and some fermented foods — and JECFA has not assigned a numerical ADI. It is metabolised via the same gluconic acid pathway as glucose oxidation products in normal human biochemistry, presenting no toxicological concerns at the quantities used in food. Both the European Food Safety Authority and international food safety bodies consider it acceptable for use without a specified intake limit.

GDL is approved throughout the EU and in most major food markets for a broad range of applications. Its most visible use is in Japanese-style silken tofu, where it produces the characteristic smooth, custard-like texture without the firmer coagulation associated with calcium or magnesium salt coagulants. In meat products such as dry-cured salami, it contributes to the acidified environment that supports safety and flavour development during curing. Consumers will find it listed as glucono delta-lactone, GDL, or E575 on ingredient panels. It is well tolerated and presents no known concerns for the general population.