Rating: Safe

Sequestrant, acidifier, leavening agent, curing agent: Nonalcoholic beverages, processed fruit and fruit juices, baked goods, dairy products, cured meats.
Gluconic acid is a metabolite of glucose. Glucono delta-lactone is the most widely used of this family of compounds and is used to adjust the acidity or as a leavening agent in baked goods, processed fruits, and dairy products. It is also used in some cured meats to speed the formation of the pink color.

All of these substances are safe. See also ferrous gluconate.