Gluconic acid

Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid.
In aqueous solution at neutral pH, gluconic acid forms the gluconate ion. The salts of gluconic acid are known as "gluconates". Gluconic acid, gluconate salts, and gluconate esters occur widely in nature because such species arise from the oxidation of glucose. Some drugs are injected in the form of gluconates.
Chemical structure.
The chemical structure of gluconic acid consists of a six-carbon chain, with five hydroxyl groups positioned in the same way as in the open-chained form of glucose, terminating in a carboxylic acid group. In aqueous solution, gluconic acid exists in equilibrium with the cyclic ester glucono delta-lactone.
Production.
Gluconic acid is produced by oxidizing glucose. This can be accomplished in several ways:
Occurrence and uses.
Gluconic acid occurs naturally in fruit, honey, and wine. In 1929 Horace Terhune Herrick developed a process for producing the salt by fermentation. As a food additive (E574), it is now known as an acidity regulator.
The gluconate anion chelates Ca2+, Fe2+, Al3+, and other metals, including lanthanides and actinides. It is also used in cleaning products, where it dissolves mineral deposits, especially in alkaline solution.
Calcium gluconate, in the form of a gel, is used to treat burns from hydrofluoric acid; calcium gluconate injections may be used for more severe cases to avoid necrosis of deep tissues, as well as to treat hypocalcemia in hospitalized patients. Gluconate is also an electrolyte present in certain solutions, such as "plasmalyte a", used for intravenous fluid resuscitation. Quinine gluconate is a salt of gluconic acid and quinine, which is used for intramuscular injection in the treatment of malaria. 
Zinc gluconate injections are used to neuter male dogs.
Ferrous gluconate injections have been proposed in the past to treat anemia.
Gluconate is also used in building and construction as a concrete admixture (retarder) to slow down the cement hydration reactions, and to delay the cement setting time. It allows for a longer time to lay the concrete, or to spread the cement hydration heat over a longer period of time to avoid too high a temperature and the resulting cracking. Retarders are mixed in to concrete when the weather temperature is high or to cast large and thick concrete slabs in successive and sufficiently well-mixed layers.