What Is Gluconic Acid?
Gluconic acid is an organic compound with the chemical formula C6H12O7. It is an optically active compound, and only the D form occurs naturally.
It is also a type of aldonic acid (a derivative obtained by oxidizing monosaccharides, in which the formyl group at the 1-position of aldose is replaced by a carboxyl group).
The CAS registration numbers are 526-95-4 for the D form and 133-42-6 for the racemic form.
Uses of Gluconic Acid
1. Food Industry
Gluconic Acid is used as a food additive because of its non-volatility and low acidity. Its main uses are as a pH adjuster for processed rice products, and as a seasoning and pH enhancer for various beverages, pickles, dressings, and sauces.
When used in foods, it is labeled as an acidifier, an hydrogen ion concentration adjuster, a pH adjuster, or gluconic acid.
Potassium gluconic acid and sodium gluconic acid, which are salts of gluconic acid, are also used as food additives.
For example, they are used to replace the processing function of salt in the manufacture of bread, soy sauce, etc. It is also used as a taste improver for the sweetener sodium saccharin.
- Calcium salts: Stabilizer
- Calcium Lactate Gluconic Acid: Calcium agent
- Iron Gluconic Acid: Black olive flavor
2. Medical Field
In the medical field, it is mainly used as a medicine for iron deficiency. The incorporated gluconic acid ions effectively facilitate the absorption of metal ions in the body.
Calcium gluconic acid ointment is also effective in the treatment of chemical wounds caused by hydrogen fluoride. Calcium ions taken up as gluconic acid salts have the ability to combine with soluble fluoride ions to form insoluble calcium fluoride, making it non-toxic.
Salts with quinine are used as a malaria treatment in the form of intramuscular injections, and zinc salts are substances used to castrate male dogs.
3. Industry
In industry, gluconic acid is sometimes used as a weak acid to remove precipitation of metal salts and to clean metals.
Properties of Gluconic Acid
Gluconic Acid is a substance that readily dehydrates to the cyclic ester glucono-delta-lactone (D-(+)-gluconic acid-δ-lactone) when dissolved in an acidic solution. Dehydration also readily occurs when attempting to isolate free acids from solution.
In aqueous solution, it exists as an equilibrium mixture with this compound, so the pure form can only be obtained in salt form.
It is also a strong chelating agent and works particularly well in alkaline solutions. Specifically, it is known to chelate calcium, iron, aluminum, copper and other heavy metal ions.
In nature, gluconic acid is particularly abundant in honey and royal jelly. Other sources include soybeans, rice, shiitake mushrooms, and fermented foods such as wine, soy sauce, and vinegar.
It is the only organic acid known to increase bifidobacteria. It has a soft sour taste and is corrosive and irritating.
Structure of Gluconic Acid
Gluconic Acid has a molecular weight of 196.155, a melting point of 131 °C, and is a colorless crystal at room temperature. It has a density of 1.23 g/mL and an acid dissociation constant pKa of 3.86. It is readily soluble in water. Its solubility in water is 316 g/L.
Gluconic Acid has a carboxyl group at the end of its six-carbon chain and five hydroxy groups, one on each of the second through sixth carbon atoms.
Types of Gluconic Acid
Gluconic Acid is sold mainly as a reagent for research and development and as an industrial raw material. Both are usually aqueous solutions of about 50%.
R&D reagent products are available in 25g, 500g, and other capacities. They are offered in capacities that are easy to handle in the laboratory.
When the term gluconic acid is used without any declaration, it usually refers to D-gluconic acid.
When sold as an industrial raw material, it is usually supplied as a raw material for food additives such as acidifiers and pH adjusters, etc. It is sold in large volumes such as 20 kg or 250 kg to meet demand at factories. This also usually refers to D-gluconic acid.
Other Information on Gluconic Acid
Biosynthesis of Gluconic Acid
Gluconic Acid is produced in the phosphogluconic acid pathway, one of the metabolic pathways of glucose in vivo. The reduced form of glucose is the sugar alcohol sorbitol, whereas the oxidized form of glucose is the sugar acid gluconic acid.