Gluconic acid is a natural organic acid belonging to the class of alpha-hydroxy acids (AHAs), which is derived from the oxidation of glucose. This acid is water-soluble and commonly appears as a white powder or crystals. It is widely used in cosmetics, the food and pharmaceutical industries, as well as in industrial applications due to its chelating, exfoliating, and detoxifying properties.
Chemical Composition and Structure
Gluconic acid consists of a six-carbon chain structure with a carboxyl group (-COOH) at one end and a hydroxyl group (-OH) at the other end. Its chemical formula is C₆H₁₂O₇. It is formed by the oxidation of glucose, removing a hydrogen atom and an aldehyde group from glucose.
Physical Properties
Appearance: Gluconic acid typically appears as a white powder or colorless crystals.
Solubility: It is highly soluble in water, making it easy to incorporate into aqueous formulations.
Odor: Gluconic acid has a neutral odor with no significant aromatic qualities.
Stability: It is stable under normal conditions but may degrade if exposed to high temperatures or intense light over prolonged periods.
Benefits and Functions
Chelating Agent: Gluconic acid is known for its ability to bind metal ions, such as calcium and magnesium, which can interfere with processes in various formulations. This property makes it useful in cleaners, water treatments, and detergents to remove scale and rust.
Exfoliating Properties: As an alpha-hydroxy acid (AHA), gluconic acid can be used in cosmetics for gently exfoliating the skin, improving texture and appearance. Unlike other AHAs, gluconic acid is milder on the skin, making it ideal for sensitive skin.
Skin Conditioning: Gluconic acid is used in personal care products for its moisturizing and refreshing properties. It also helps improve skin brightness and promotes cell renewal.
Antibacterial and Antimicrobial Properties: Some studies suggest that gluconic acid has mild antibacterial properties, making it useful in certain cosmetic and medical applications.
pH Regulator: Gluconic acid is also used to regulate the pH of formulations, improving product stability.
Applications
Cosmetics and Personal Care
Facial exfoliators and scrubs: Gluconic acid is used in many exfoliating products for its ability to remove dead skin cells gently.
Anti-aging serums and creams: Due to its exfoliating properties and its ability to stimulate cell renewal, it is included in anti-aging products to improve skin brightness and combat signs of aging.
Moisturizers: Gluconic acid helps retain skin moisture and is used in lotions and creams for hydration.
Sensitive skin products: Because it is milder than other AHAs, it is ideal for sensitive skin and is often used in gentle formulations for skin care.
Food Industry
Food Additive: Gluconic acid is used as a food additive (E574), particularly as a chelating agent and preservative. It is used in some cheeses and baked goods to improve shelf life and quality.
Flavor and Acidity: It can be used to regulate acidity and impart a mildly acidic flavor to certain foods.
Pharmaceuticals
Mineral Supplementation: Calcium gluconate, derived from gluconic acid, is used for pharmaceutical treatments of calcium deficiencies.
Bone and Dental Treatments: Calcium gluconate is also used in medications for treating bone and dental conditions.
Industry
Water Treatment: Gluconic acid is used in water treatment processes to remove calcium and other minerals that could compromise the efficiency of industrial equipment and boilers.
Cleaning Products: Due to its chelating properties, gluconic acid is used in industrial cleaners to remove mineral build-up from hard surfaces.
Environmental and Safety Considerations
Biodegradability: Gluconic acid is fully biodegradable and has a minimal environmental impact, making it a safe choice for use in eco-friendly products.
Safety: Gluconic acid is generally considered safe for use in cosmetics and food products. However, as with any ingredient, it is important to follow recommended dosages, particularly in pharmaceutical applications.
Sustainability: Gluconic acid is primarily produced from glucose, a renewable resource, making it a sustainable choice compared to other synthetic acids.
It appears as a yellow liquid.
Studies
Food
Ingredient included in the list of European food additives as E574 with the function of antioxidant, acidity regulator. Improves the organoleptic properties of foodstuffs, imparting a particular, less bitter flavour. In fruit juices, it prevents cloudiness (1). It is an ingredient that has been proposed as a quality parameter for food products (2).
Cosmetics
Chelating agent. It has the function of preventing unstable reactions and improving the bioavailability of chemical components within a product, and removes calcium and magnesium cations that can cause cloudiness in clear liquids.
Fragrance. It plays a decisive and important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability. The consumer always expects to find a pleasant or distinctive scent in a cosmetic product.
Other uses
- Growth-promoting substance for bifidobacteria
- Textiles, leather, metallurgy, animal feed
- Molecular Formula C6H12O7 C6H12O7
- Molecular Weight 196.16
- CAS 526-95-4
- UNII R4R8J0Q44B
- EC Number 208-401-4
References_____________________________________________________________________
(1) Kornecki, J.F., Carballares, D., Tardioli, P.W., Rodrigues, R.C., Berenguer-Murcia, Á., Alcantara, A.R. and Fernandez-Lafuente, R., 2020. Enzyme production of D-gluconic acid and glucose oxidase: successful tales of cascade reactions. Catalysis Science & Technology, 10(17), pp.5740-5771.
Abstract. This review mainly focuses on the use of glucose oxidase in the production of D-gluconic acid, which is a reactant of undoubtable interest in different industrial areas. The enzyme has been used in numerous instances as a model reaction to study the problems of oxygen supply in bioreactors. One of the main topics in this review is the problem of the generated side product, hydrogen peroxide, as it is an enzyme-inactivating reagent. Different ways to remove hydrogen peroxide have been used, such as metal catalysts and use of whole cells; however, the preferred method is the coupling glucose oxidase with catalase. The different possibilities of combining these enzymes have been discussed (use of free enzymes, independently immobilized enzymes or co-immobilized enzymes). Curiously, some studies propose the addition of hydrogen peroxide to this co-immobilized enzyme system to produce oxygen in situ. Other cascade reactions directed toward the production of gluconic acid from polymeric substrates will be presented; these will mainly involve the transformation of polysaccharides (amylases, cellulases, etc.) but will not be limited to those (e.g., gluconolactonase). In fact, glucose oxidase is perhaps one of most successful enzymes, and it is involved in a wide range of cascade reactions. Finally, other applications of the enzyme have been reviewed, always based on the production of D-gluconic acid, which produces a decrease in the pH, a decrease in the oxygen availability or the production of hydrogen peroxide; in many instances, cascade reactions are also utilized. Thus, this review presents many different cascade reactions and discusses the advantages/drawbacks of the use of co-immobilized enzymes.
(2) Gomes, R.J., de Fatima Borges, M., de Freitas Rosa, M., Castro-Gómez, R.J.H. and Spinosa, W.A., 2018. Acetic acid bacteria in the food industry: systematics, characteristics and applications. Food technology and biotechnology, 56(2), p.139.
Abstract. The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of food and beverages, such as vinegar and kombucha. The ability to oxidise ethanol to acetic acid also allows the unwanted growth of AAB in other fermented beverages, such as wine, cider, beer and functional and soft beverages, causing an undesirable sour taste. These bacteria are also used in the production of other metabolic products, for example, gluconic acid, l-sorbose and bacterial cellulose, with potential applications in the food and biomedical industries. The classification of AAB into distinct genera has undergone several modifications over the last years, based on morphological, physiological and genetic characteristics. Therefore, this review focuses on the history of taxonomy, biochemical aspects and methods of isolation, identification and quantification of AAB, mainly related to those with important biotechnological applications.
Anastassiadis S, Morgunov IG. Gluconic acid production. Recent Pat Biotechnol. 2007;1(2):167-80. doi: 10.2174/187220807780809472.
Abstract. Gluconic acid, the oxidation product of glucose, is a mild neither caustic nor corrosive, non toxic and readily biodegradable organic acid of great interest for many applications. As a multifunctional carbonic acid belonging to the bulk chemicals and due to its physiological and chemical characteristics, gluconic acid itself, its salts (e.g. alkali metal salts, in especially sodium gluconate) and the gluconolactone form have found extensively versatile uses in the chemical, pharmaceutical, food, construction and other industries. Present review article presents the comprehensive information of patent bibliography for the production of gluconic acid and compares the advantages and disadvantages of known processes. Numerous manufacturing processes are described in the international bibliography and patent literature of the last 100 years for the production of gluconic acid from glucose, including chemical and electrochemical catalysis, enzymatic biocatalysis by free or immobilized enzymes in specialized enzyme bioreactors as well as discontinuous and continuous fermentation processes using free growing or immobilized cells of various microorganisms, including bacteria, yeast-like fungi and fungi. Alternatively, new superior fermentation processes have been developed and extensively described for the continuous and discontinuous production of gluconic acid by isolated strains of yeast-like mold Aureobasidium pullulans, offering numerous advantages over the traditional discontinuous fungi processes.
Gluconic acid 
