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Gluconolactone, also known as gluconolactone, D-glucono-1,5-lactone or GDL (CAS No 90-80-2, C6H10O6, food additive E575), is the cyclic inner ester of D-gluconic acid, supplied as a white, practically odourless crystalline powder and used as a slow-release acidulant, protein coagulant, leavening acid, curing accelerator and sequestrant in food, and as a mild polyhydroxy acid (PHA), chelating and skin-conditioning agent in cosmetics.
D-glucono-1,5-lactone is preferred over citric, lactic or acetic acid when the pH must fall gradually instead of instantly, because it is neutral when it is added and only becomes acidic as it reacts with water, the result is uniform gels and curds, controlled gas release in dough and a much milder, less tart taste.
GDL works by hydrolysis: after it dissolves, the lactone ring slowly opens to form gluconic acid until an equilibrium between the acid and its lactones is reached, and the rate of this reaction can be steered with temperature, concentration and pH.
CAS No: 90-80-2
EC No: 202-016-5
Molecular formula: C6H10O6
Molecular weight: 178.14 g/mol
Food additive number: E575 (INS 575)
INCI name: Gluconolactone
Appearance: White, fine crystalline powder, practically odourless, slightly sweet taste
Melting point: approx. 150–160 °C (with decomposition)
Water solubility: approx. 59 g/100 mL at 20–25 °C (hydrolyses in solution)
pH (1 % solution): approx. 3.6 when freshly prepared, falling to approx. 2.5 as hydrolysis proceeds
COMMON PRODUCT & CHEMICAL NAMES of GLUCONO-DELTA-LACTONE GDL:
Glucono-delta-lactone GdL, Glucono-delta-lactone, Glucono Delta Lactone, Glucono-δ-lactone, GDL, GdL, Gluconolactone, Delta-Gluconolactone, δ-Gluconolactone, D-Gluconolactone, D-Glucono-1,5-lactone, 1,5-Gluconolactone, D-Gluconic acid delta-lactone, D-Gluconic acid 1,5-lactone, D-(+)-Gluconic acid δ-lactone, D-(+)-Glucono-1,5-lactone, Gluconic acid lactone, Gluconic lactone, D-threo-Aldono-1,5-lactone, (3R,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)oxan-2-one, (3R,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-one, 1,2,3,4,5-Pentahydroxycaproic acid delta-lactone, D-(+)-Dextronic acid delta-lactone, Gluconolactone USP, Glucono Delta-Lactone FCC, E575, E 575, INS 575, Fujiglucon, Lysactone, Riken Lactone
Gluconolactone is the INCI and pharmacopoeia name (USP) of GLUCONO-DELTA-LACTONE GDL, glucono-delta-lactone is the name used in the EU food additive list and the Food Chemicals Codex, and D-glucono-1,5-lactone is the chemical name that shows where the ring closes: between the carboxyl group (C1) and the hydroxyl group on carbon 5. The Greek letter delta refers to this six-membered ring. "GDL" and "GdL" are simply abbreviations used by producers and food technologists. Fujiglucon, Lysactone and Riken Lactone are trade names that have been used for the same substance.
Glucono-delta-lactone should not be confused with gamma-gluconolactone (D-glucono-1,4-lactone, the five-membered ring isomer that occurs as a minor species in solution), with glucuronolactone (D-glucurono-6,3-lactone, a different substance known from energy drinks), with glucarolactone (a lactone of glucaric acid) or with the salts of gluconic acid such as sodium gluconate (E576) and calcium gluconate (E578). Older synonym lists sometimes mix these names, they describe different products.
WHAT IS GLUCONO-DELTA-LACTONE GDL?
The defining feature of GLUCONO-DELTA-LACTONE GDL is its delayed acidity. Dry GLUCONO-DELTA-LACTONE GDL is not an acid in the usual sense, so it can be blended into powders, brines or soy milk without an immediate pH shock. Only after dissolution does GLUCONO-DELTA-LACTONE GDL start to release gluconic acid, and the pH drops in a smooth, continuous curve. Food technologists often compare this to the gentle acidification produced by lactic acid bacteria, but without the variability of a live culture.
The second feature of GLUCONO-DELTA-LACTONE GDL is its taste. Gluconolactone starts slightly sweet and ends only mildly sour, gluconic acid is commonly described as having roughly one third of the sourness of citric acid. This lets GLUCONO-DELTA-LACTONE GDL lower pH in tofu, cheese, meat products and dressings without making them taste sharp.
D-glucono-1,5-lactone is produced from glucose. Glucose, usually from corn or other starch, is oxidised to gluconic acid by fermentation (typically with Aspergillus niger) or by enzymatic oxidation, and GLUCONO-DELTA-LACTONE GDL is then crystallised from the concentrated gluconic acid solution and separated from the mother liquor. Gluconic acid itself occurs naturally in honey, wine, fruit juices and many fermented foods, which is why GLUCONO-DELTA-LACTONE GDL is widely presented as a naturally occurring food ingredient.
Typical places where GLUCONO-DELTA-LACTONE GDL is found: silken and soft tofu, tofu pudding, feta, mozzarella and other cheeses, cottage and cream cheese products, cooked and fermented sausages, cured hams and comminuted meat, fish and seafood products, baking powders, cake mixes, pizza dough and biscuits, dressings, sauces and mayonnaise, desserts and fruit preparations, skin care creams, serums, toners and peels, hair care products, toothpaste, deodorants, preservative systems, dairy and brewery cleaning compounds, and alginate or protein gels in research and food engineering.
GDL is a carbohydrate-derived lactone. In chemical terms, GLUCONO-DELTA-LACTONE GDL is an aldono-1,5-lactone: the open-chain D-gluconic acid (C6H12O7) loses one molecule of water as its C1 carboxyl group reacts internally with the C5 hydroxyl group, closing a six-membered pyranose-like ring. Four hydroxyl groups remain on the ring and on the side chain, which explains the high water solubility of GLUCONO-DELTA-LACTONE GDL and its moisture-binding character in cosmetics.
Because GLUCONO-DELTA-LACTONE GDL is an ester, it is chemically neutral as a dry powder. In water the ester bond is hydrolysed and GLUCONO-DELTA-LACTONE GDL turns into gluconic acid, a weak organic acid. The reaction is reversible, so a solution of GLUCONO-DELTA-LACTONE GDL is never pure lactone or pure acid but an equilibrium mixture.
In the body, GLUCONO-DELTA-LACTONE GDL is treated as a normal metabolite: it is hydrolysed to gluconate, which enters the pentose phosphate pathway via 6-phospho-D-gluconate. One gram of GLUCONO-DELTA-LACTONE GDL supplies roughly the same energy as one gram of sugar.
CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF GLUCONO-DELTA-LACTONE GDL
Product name: GLUCONO-DELTA-LACTONE GDL
Chemical name: D-Glucono-1,5-lactone
IUPAC name: (3R,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)oxan-2-one
CAS No: 90-80-2
EC / EINECS No: 202-016-5
Molecular formula: C6H10O6
Molecular weight: 178.14 g/mol
Food additive number: E575 (EU), INS 575 (Codex)
INCI name: Gluconolactone
Pharmacopoeia name: Gluconolactone (USP)
Chemical class: Aldonolactone, cyclic ester of D-gluconic acid, polyhydroxy acid (PHA) precursor
Main functions: Slow-release acidulant, acidity regulator, protein coagulant, leavening acid, curing and pickling agent, sequestrant, chelating agent, skin-conditioning agent, mild exfoliant
Only CAS 90-80-2 and EC 202-016-5 should be used for GLUCONO-DELTA-LACTONE GDL in purchasing documents. Other CAS numbers that appear in some databases next to gluconolactone belong to other stereoisomers, mixtures or deprecated entries and should not be copied into specifications.
STRUCTURE OF GLUCONO-DELTA-LACTONE GDL
Glucono-delta-lactone has four stereocentres with the same configuration as D-glucose (D-gluco series), a ring oxygen, a lactone carbonyl at C1 and a hydroxymethyl side chain at C5. The structure can be summarised as follows:
- six-membered lactone ring (delta-lactone, 1,5-ring closure)
- three secondary hydroxyl groups on the ring (C2, C3, C4)
- one primary hydroxyl group on the CH2OH side chain (C6)
- strongly hydrophilic molecule (log P approx. -2)
Hydrolysis opens the ring:
C6H10O6 + H2O ⇌ C6H12O7 (gluconic acid)
Gluconic acid can also re-close to the five-membered gamma-lactone (1,4-lactone), so a solution of GLUCONO-DELTA-LACTONE GDL contains three species: gluconic acid, delta-lactone and a smaller amount of gamma-lactone.
PHYSICAL AND CHEMICAL PROPERTIES OF GLUCONO-DELTA-LACTONE GDL
Physical state: Solid, fine crystalline powder (granular grades are also available)
Colour: White to almost white
Odour: Practically odourless
Taste: Slightly sweet at first, mildly acidic after hydrolysis
Molecular weight: 178.14 g/mol
Melting point: approx. 150–160 °C, with decomposition
Density: approx. 1.7 g/cm³
Bulk density: approx. 750 kg/m³ (grade dependent)
Solubility in water: Freely soluble, approx. 59 g/100 mL at 20–25 °C (with gradual hydrolysis)
Solubility in ethanol: Slightly soluble (approx. 1 g/100 g)
Solubility in ether: Practically insoluble
pH (10 g/L, 20 °C): approx. 3.6 directly after dissolution, approx. 2.5 after the hydrolysis equilibrium is reached
Optical activity: Dextrorotatory, the rotation changes over time in solution as the lactone hydrolyses (mutarotation)
Log P: approx. -2
Stability: Stable in dry, closed packaging at room temperature, hydrolyses in the presence of water or humid air
Flash point: Not applicable (combustible solid)
Values for assay, loss on drying, reducing substances, lead and particle size distribution depend on the grade (food, USP or cosmetic). Grade-specific specifications are available on request from Ataman Kimya.
HYDROLYSIS: HOW GLUCONO-DELTA-LACTONE GDL LOWERS pH
Everything GLUCONO-DELTA-LACTONE GDL does in a recipe follows from one reaction. When GLUCONO-DELTA-LACTONE GDL dissolves, the pH of the solution starts close to the pH of the medium and then falls as gluconic acid forms. In a freshly prepared 1 % solution in pure water, the pH drops from about 3.6 to about 2.5 within roughly two hours at room temperature. In cold water the final equilibrium contains about 55–60 % gluconic acid and 40–45 % delta- and gamma-lactones.
The speed of this pH drop is not fixed. It can be controlled:
Temperature: higher temperature accelerates hydrolysis of GLUCONO-DELTA-LACTONE GDL considerably. This is used in tofu (hot soy milk), in cooked sausages and in baking, where most acid is released in the oven.
Concentration: more GLUCONO-DELTA-LACTONE GDL gives a lower final pH and a faster initial drop.
pH and buffering: hydrolysis is faster at higher (neutral to alkaline) pH. In buffered systems such as milk, soy milk or meat, proteins and salts absorb part of the acid, so the final pH depends on the buffer capacity of the food as well as on the dosage of GLUCONO-DELTA-LACTONE GDL.
For practical work this means that GLUCONO-DELTA-LACTONE GDL should be added at the last possible step, the system should be mixed quickly, and the time between dosing and gelation, filling or forming should be kept constant from batch to batch.
SECTORS WHERE GLUCONO-DELTA-LACTONE GDL IS USED
- Food: soy products, dairy and cheese, meat and sausages, fish and seafood, bakery and mixes, sauces, dressings, desserts, ready meals
- Beverages: acidity regulation in instant drinks and some ready-to-drink products
- Food ingredients: baking powder blends, tofu coagulant blends, seasoning blends, curing mixes
- Cosmetics and personal care: skin care, hair care, oral care, deodorants
- Pharmaceuticals: excipient and pH adjusting agent, component of irrigation solutions
- Household and industrial cleaning: sequestering component in cleaning compositions
- Food plant hygiene: prevention of milkstone and beerstone
- Textiles: latent acid catalyst in printing and finishing
- Construction chemicals, fine chemicals and research laboratories
Glucono-delta-lactone GdL IN SOY PRODUCTS, DAIRY AND CHEESE
Tofu is the best-known application of GLUCONO-DELTA-LACTONE GDL. Traditional coagulants such as magnesium chloride (nigari) or calcium sulphate (gypsum) work through divalent cations, GLUCONO-DELTA-LACTONE GDL works through acid instead. As gluconic acid forms in the hot soy milk, the soy proteins reach their isoelectric region evenly throughout the whole volume, and a fine, smooth and glossy gel forms without stirring. This is why GLUCONO-DELTA-LACTONE GDL is the classic coagulant for silken tofu, packed tofu and tofu pudding (douhua), where the soy milk is mixed with the coagulant, filled into the pack and then set by heating.
Gluconolactone can be used alone or blended with nigari or calcium sulphate. Blends combine the smooth texture from GLUCONO-DELTA-LACTONE GDL with the firmer bite and calcium contribution of the salt coagulants. Used alone at high dosage, GLUCONO-DELTA-LACTONE GDL can give a slightly sour note, which is one reason blends are popular.
In dairy, GLUCONO-DELTA-LACTONE GDL is used for direct acidification of milk-based products. Feta-type and white brined cheeses, mozzarella, cottage cheese and cream cheese products can be acidified with GLUCONO-DELTA-LACTONE GDL instead of, or together with, starter cultures. Because the gel is formed by acid that is generated inside the milk, there is no local curdling at the point of addition. In set desserts and some dairy products, GLUCONO-DELTA-LACTONE GDL allows the product to be filled while still liquid and to gel afterwards in the pack.
Glucono-delta-lactone GdL IN MEAT, SAUSAGE AND FISH PRODUCTS
In cured meat products, pH controls several processes at the same time: colour formation from nitrite, protein coagulation, drying and microbial stability. D-glucono-1,5-lactone is added to the meat batter, brine or curing mix and lowers the pH progressively as it hydrolyses in the moist meat.
Typical effects of GLUCONO-DELTA-LACTONE GDL in meat:
- faster and more uniform development and fixing of the cured red colour
- faster acidification and setting of fermented and dry sausages, especially when starter culture acidification alone is too slow
- shorter smoking or ripening time in some processes
- better slicing behaviour and firmer texture in fermented products
- a contribution to microbial stability through lower pH
Combined with reducing agents such as sodium ascorbate or sodium erythorbate, GLUCONO-DELTA-LACTONE GDL can make colour development during cooking and smoking very fast, so processes should be validated when both are used. Dosage must be kept within limits: too much GLUCONO-DELTA-LACTONE GDL lowers the water-holding capacity of meat proteins and gives a sour taste, which is acceptable in salami-type products but not in cooked sausages.
In fish and seafood products, GLUCONO-DELTA-LACTONE GDL is used for mild acidification and as a sequestrant that helps limit discolouration.
Glucono-delta-lactone GdL AS A LEAVENING ACID
In chemical leavening, GLUCONO-DELTA-LACTONE GDL is the acid component that reacts with sodium bicarbonate to release carbon dioxide. Because the acid is generated progressively, only a small part of the gas is released during mixing at low temperature, and most is released as the dough or batter warms up in the oven. This gives GLUCONO-DELTA-LACTONE GDL a reaction profile similar to slower leavening phosphates, with a clean, non-metallic aftertaste.
Stoichiometrically, 1 mol of GLUCONO-DELTA-LACTONE GDL (178 g) neutralises 1 mol of sodium bicarbonate (84 g), so about 2.1 parts GLUCONO-DELTA-LACTONE GDL are needed per 1 part sodium bicarbonate, practical baking powder blends are usually formulated around a 2:1 ratio and then adjusted to the target crumb pH. GDL is used in cake and muffin mixes, pizza dough, biscuits, crackers, steamed buns and phosphate-free baking powders.
COSMETIC, FOOD AND PHARMACEUTICAL APPLICATIONS OF GLUCONO-DELTA-LACTONE GDL
Cosmetics and personal care
In cosmetic ingredient lists, GLUCONO-DELTA-LACTONE GDL appears as Gluconolactone. Its listed functions in the EU cosmetic ingredient database are chelating and skin conditioning. Glucono-delta-lactone belongs to the polyhydroxy acids (PHA), which are used as gentler alternatives to alpha hydroxy acids such as glycolic acid: the larger, highly hydroxylated molecule penetrates the skin more slowly, exfoliates more mildly and also binds water. Gluconolactone is used in creams, lotions, serums, toners, peel products, products for sensitive skin, shampoos and conditioners, deodorants and toothpaste. D-glucono-1,5-lactone is also used as a component of preservative-boosting systems, for example in combination with sodium benzoate, where its chelating action and pH reduction support the preservative.
In aqueous cosmetic formulas, GLUCONO-DELTA-LACTONE GDL lowers pH over time, so the final pH should be measured after the hydrolysis equilibrium has been reached and corrected if needed.
Food
GDL is approved as food additive E575. In the EU it is a Group I additive that may be used at quantum satis in many food categories and is also permitted in some specific categories with defined conditions. Its main food functions are acidity regulation, coagulation, leavening, curing acceleration and sequestering.
Pharmaceuticals
Gluconolactone is described in the USP. Glucono-delta-lactone is used as an excipient and pH adjusting agent, and it is one of the components of an irrigation solution (together with citric acid and magnesium carbonate) used for the dissolution of certain urinary calculi. Its good safety record and complete metabolism make GLUCONO-DELTA-LACTONE GDL suitable for oral products, effervescent systems and supplements.
INDUSTRIAL APPLICATIONS OF GLUCONO-DELTA-LACTONE GDL
Cleaning compositions: GLUCONO-DELTA-LACTONE GDL releases gluconate, which sequesters calcium, magnesium and iron ions. For this reason GLUCONO-DELTA-LACTONE GDL has been used in cleaning compounds, in the dairy industry to prevent milkstone and in breweries to prevent beerstone deposits.
Textile printing and finishing: GLUCONO-DELTA-LACTONE GDL has been used as a latent acid catalyst, because it remains neutral during preparation and only becomes acidic in the presence of water and heat.
Controlled gelation: GLUCONO-DELTA-LACTONE GDL is widely used in food engineering and laboratories for internal gelation, for example alginate gels made with calcium carbonate and GLUCONO-DELTA-LACTONE GDL, where the slowly released acid frees calcium ions from the carbonate and produces a homogeneous gel. The same principle is used for acid-induced gels of milk proteins and soy proteins.
Construction and fine chemicals: GLUCONO-DELTA-LACTONE GDL is used as a source of gluconate and as an acidifying, buffering and chelating agent.
Fermentation and biotechnology: GLUCONO-DELTA-LACTONE GDL is a carbon source for some microorganisms and is used in enzyme studies as a beta-glucosidase inhibitor.
WHICH PROBLEMS DOES GLUCONO-DELTA-LACTONE GDL SOLVE?
Problem: The protein gel forms lumps or curdles locally when acid is added.
Glucono-delta-lactone GdL solution: the acid is generated evenly throughout the whole volume, so the gel is homogeneous.
Problem: The product becomes too sour when the target pH is reached with citric or lactic acid.
Glucono-delta-lactone GdL solution: the same pH reduction is achieved with a much milder taste.
Problem: A liquid product must be filled first and set later.
Glucono-delta-lactone GdL solution: the delay between dosing and gelation allows filling, packing and then heat setting.
Problem: Fermented sausages take too long to acidify and dry.
Glucono-delta-lactone GdL solution: faster and more predictable pH reduction and colour development.
Problem: A phosphate-free leavening acid is needed.
Gluconolactone solution: GLUCONO-DELTA-LACTONE GDL reacts with sodium bicarbonate and is free of phosphate and aluminium.
Problem: A cosmetic exfoliant is too irritating for sensitive skin.
D-glucono-1,5-lactone solution: as a PHA, GLUCONO-DELTA-LACTONE GDL offers milder exfoliation and additional moisturising.
THINGS TO CONSIDER WHEN USING GLUCONO-DELTA-LACTONE GDL
- Add GLUCONO-DELTA-LACTONE GDL as late as possible. Once dissolved, GLUCONO-DELTA-LACTONE GDL starts to hydrolyse and the clock starts running.
- Do not prepare stock solutions of GLUCONO-DELTA-LACTONE GDL in advance, a solution kept for hours is already largely gluconic acid and behaves like a normal acid.
- Keep process temperature and holding times constant, because they control the acidification rate of GLUCONO-DELTA-LACTONE GDL more than any other parameter.
- Take buffer capacity into account. Milk, soy milk and meat absorb part of the acid, so dosages from water-based tests cannot be transferred directly.
- Overdosing gives sour taste in foods and a too-low pH in cosmetics, in meat it reduces water binding.
- Measure the final pH only after equilibrium has been reached.
- Protect the powder from humidity. Moisture causes caking and premature hydrolysis inside the bag.
- Check the legal status of GLUCONO-DELTA-LACTONE GDL for the specific food category and target market before launch.
INITIAL FORMULATION APPROACHES WITH GLUCONO-DELTA-LACTONE GDL
The component percentages below are illustrative starting points, not validated commercial recipes. Final proportions must be established through laboratory testing.
1. Silken tofu (packed, heat set)
Illustrative initial components (% w/w of the complete batch):
Prepared soy milk: 99.75 %
Glucono-delta-lactone: 0.25 %
Total: 100.00 %
Prepare soy milk at the required solids content, deaerate and cool to below about 30 °C. Dissolve GLUCONO-DELTA-LACTONE GDL in a small amount of cold water immediately before use, or add the powder directly, and mix quickly, a typical starting level is about 0.2–0.3 % GLUCONO-DELTA-LACTONE GDL based on soy milk weight. Fill into cups or bags, seal and heat in a water bath or steam at about 85–90 °C for 20–40 minutes, then cool. Adjust the dosage up for firmer texture, or replace part of GLUCONO-DELTA-LACTONE GDL with nigari or calcium sulphate for a less acidic taste.
2. Cooked sausage or ham with faster colour fixing
Illustrative initial components (% w/w of the complete batch):
Prepared meat formulation, including the application-specific curing ingredients: 99.80 %
Glucono-delta-lactone: 0.20 %
Total: 100.00 %
The meat formulation is a pre-established base, its individual curing ingredients and legal limits must be specified separately for the intended product.
Add GLUCONO-DELTA-LACTONE GDL to the batter or brine together with the curing salt, a typical starting range is about 0.1–0.3 % GLUCONO-DELTA-LACTONE GDL based on meat. Higher levels, roughly 0.5–0.8 % or more, are reserved for products with a deliberately acidic profile such as some fermented or salami-type sausages. Monitor colour, pH, yield and taste, and validate the process if sodium ascorbate or erythorbate is also used. National meat regulations may set maximum amounts.
3. Phosphate-free baking powder
Illustrative initial components (% w/w of the complete premix):
Glucono-delta-lactone: 60.00 %
Sodium bicarbonate: 30.00 %
Dry starch carrier: 10.00 %
Total: 100.00 %
Blend GLUCONO-DELTA-LACTONE GDL and sodium bicarbonate at about 2:1 (by weight) with a dry starch carrier to separate the reactants. Use the blend at about 2–3 % of flour weight as a starting point, check volume and crumb pH, and fine-tune the GLUCONO-DELTA-LACTONE GDL to bicarbonate ratio to avoid soapy (excess soda) or sour (excess acid) notes.
These starting points are not final recipes. Each formulation with GLUCONO-DELTA-LACTONE GDL must be optimised with the actual raw materials and process conditions.
HOW DOES GLUCONO-DELTA-LACTONE WORK AT THE MOLECULAR LEVEL?
Glucono-Delta-Lactone (GDL) is the six-membered cyclic inner ester of D-gluconic acid. In solid form the molecule is neutral; its acidity develops only after contact with water, and only over time. This delayed behaviour explains most of what the product does in food and industrial systems.
Hydrolysis and gradual acidification: When Glucono-Delta-Lactone dissolves in water, the lactone ring reacts with water and slowly opens to form gluconic acid. An equilibrium is eventually established between gluconic acid, the delta-lactone and the gamma-lactone. A freshly prepared solution starts at a relatively high pH; as hydrolysis proceeds, the acid content rises and the pH falls. Higher temperature and higher pH both speed up hydrolysis, so the rate of acidification is controlled by process temperature as much as by dosage.
Protein coagulation: In tofu and certain dairy products, GDL acidifies the system slowly and evenly instead of all at once. As the pH approaches the isoelectric point of the proteins, their net charge decreases and electrostatic repulsion between them weakens. Proteins then link together into a three-dimensional network that holds water inside. Because no free acid is added directly, coagulation starts throughout the whole mass at the same time, giving a smoother and softer gel.
Meat curing: In non-fermented sausages and similar products, Glucono-Delta-Lactone provides chemically the acidification that microbial fermentation would otherwise supply. The lower pH accelerates the conversion of nitrite to nitric oxide, which binds to myoglobin and forms the typical cured meat colour. Reduced pH also lowers the water-holding capacity of meat proteins, supporting drying and the development of a firm, sliceable texture.
Leavening acid: In baking powders, GDL acts as the acid component paired with sodium bicarbonate. As the lactone hydrolyses in the dough water, the released gluconic acid neutralises the bicarbonate and carbon dioxide gas is liberated. Since hydrolysis is gradual, gas release is also spread over time rather than occurring in a single burst.
Taste profile: The lactone itself is not acidic and has a slightly sweet taste. Because acidity forms only through hydrolysis, no sharp sourness is perceived at first; the final product shows a milder acid taste than many other food acids.
Chelation: The gluconate anion formed by hydrolysis carries a carboxylate group and several hydroxyl groups, allowing it to form complexes with calcium, iron and other metal ions. This sequestering effect helps limit haze, discolouration and oxidation reactions caused by metal ions; the same mechanism is used in cleaning and metal surface treatment.
Behaviour in the body: In the digestive tract, the lactone hydrolyses to gluconic acid. Gluconic acid is a natural intermediate of carbohydrate metabolism and, after phosphorylation, is metabolised through the pentose phosphate pathway. For this reason, assessments are based on gluconic acid and gluconates rather than on the lactone alone.
The final level and speed of acidification depend not only on dosage but also on temperature, starting pH, the buffering capacity of the system and its protein content. Glucono-Delta-Lactone dosage and process conditions should therefore be confirmed through laboratory trials.
ALTERNATIVES TO GLUCONO-DELTA-LACTONE GDL
Citric acid, lactic acid, malic acid and acetic acid: immediate acidification and stronger taste, no delayed effect.
Encapsulated acids: delayed release by coating instead of by chemistry, often used in meat.
Starter cultures: biological acidification, slower and dependent on fermentation conditions, but gives typical fermented flavour.
Magnesium chloride (nigari) and calcium sulphate: tofu coagulants that act through cations, firmer texture and different taste.
Sodium aluminium phosphate, sodium acid pyrophosphate (SAPP) and monocalcium phosphate: leavening acids with defined reaction rates, contain phosphate and in some cases aluminium.
Sodium gluconate and calcium gluconate: provide gluconate for sequestering without acidification.
Glycolic acid, lactic acid and lactobionic acid: alternative cosmetic exfoliating acids, AHA are stronger, lactobionic acid is another PHA-type option.
GDL remains the first choice when slow, uniform acidification and a mild taste are needed in the same product.
QUALITY CONTROL AND PURCHASING CRITERIA FOR GLUCONO-DELTA-LACTONE GDL
When buying GLUCONO-DELTA-LACTONE GDL, the following points are normally checked:
- identity: CAS 90-80-2, E575, Gluconolactone (INCI/USP)
- grade: food (EU/FCC/JECFA specifications), USP pharmaceutical grade or cosmetic grade
- assay (typically about 99.0–101.0 % for pharmacopoeia grades)
- loss on drying or water content
- reducing substances
- heavy metals and lead
- particle size (fine powder or granular), important for dissolution speed and dusting
- microbiological quality for food and cosmetic use
- certificates: kosher, halal, non-GMO, vegan suitability, allergen statement, and, if required, documentation for organic processing
- documents: COA, TDS, SDS, specification and shelf-life statement
Exact specification limits and shelf life of the GLUCONO-DELTA-LACTONE GDL grades supplied are available on request from Ataman Kimya.
STORAGE AND HANDLING OF GLUCONO-DELTA-LACTONE GDL
Store GLUCONO-DELTA-LACTONE GDL in tightly closed original packaging in a cool, dry and well-ventilated place, typically at about 2–30 °C, away from moisture and direct heat. Opened bags should be closed immediately after use, because humid air starts the hydrolysis of GLUCONO-DELTA-LACTONE GDL and leads to caking. Avoid dust formation when emptying bags and use local exhaust where powders are handled in large quantities. Keep GLUCONO-DELTA-LACTONE GDL away from strong alkalis and strong oxidising agents. Fine organic dust can form explosive mixtures in air, so normal dust explosion precautions apply.
SAFETY OF GLUCONO-DELTA-LACTONE GDL
Glucono-delta-lactone is not classified as hazardous under the EU CLP Regulation according to typical supplier safety data sheets, and it is not regulated as dangerous goods for transport. In Germany it is assigned to water hazard class WGK 1 (slightly hazardous to water).
As a fine powder, GLUCONO-DELTA-LACTONE GDL can cause mild mechanical irritation of the eyes and respiratory tract, and concentrated solutions are mildly acidic. Recommended precautions are safety glasses, gloves for prolonged contact and a particle filter mask (for example P1/FFP1) when dust is generated.
First aid: after inhalation, move to fresh air, after skin contact, rinse with water, after eye contact, rinse thoroughly with plenty of water and remove contact lenses, after swallowing large amounts, rinse the mouth and drink water, and seek medical advice if discomfort occurs.
Fire: GLUCONO-DELTA-LACTONE GDL is a combustible solid. Suitable extinguishing media are water spray, foam, carbon dioxide and dry powder. When heated to decomposition, GLUCONO-DELTA-LACTONE GDL can release irritating fumes and carbon oxides.
Environment: GLUCONO-DELTA-LACTONE GDL is readily biodegradable. Large quantities should not be released into drains, because the acidification can disturb water pH.
Regulatory status (summary):
- EU: authorised food additive E575 under Regulation (EC) No 1333/2008, specifications in Regulation (EU) No 231/2012. The Scientific Committee for Food set an ADI "not specified", EFSA re-evaluation of gluconic acid and its salts and lactone is part of the ongoing EU programme.
- JECFA: group ADI "not specified" for glucono-delta-lactone and gluconates.
- USA: GRAS as a direct food ingredient (21 CFR 184.1318) for use as curing and pickling agent, leavening agent, pH control agent and sequestrant at levels consistent with good manufacturing practice, meat and poultry use is regulated by USDA (for example in cured comminuted meat products).
- Organic: in the USA, non-synthetic GLUCONO-DELTA-LACTONE GDL is listed for organic processing, production by bromine-water oxidation of glucose is not allowed for this use.
For the complete hazard and handling information, the SDS of the supplied grade can be requested from Ataman Kimya.
BUYING GLUCONO-DELTA-LACTONE GDL
Gluconolactone is normally supplied as a fine crystalline powder, and in some grades as granules, in multi-layer paper bags with PE inner liner or in big bags. When ordering GLUCONO-DELTA-LACTONE GDL, buyers should state the intended application (tofu, dairy, meat, bakery, cosmetic, pharmaceutical or technical), the required grade and pharmacopoeia, the preferred particle size, the packaging type and the documents needed. Available pack sizes, lead times and grades are available on request from Ataman Kimya.
SUPPLY OF GLUCONO-DELTA-LACTONE GDL FROM ATAMAN KIMYA
Ataman Kimya supplies GLUCONO-DELTA-LACTONE GDL for food, cosmetic, pharmaceutical and industrial customers. Ataman Kimya can support customers with product selection, technical data, SDS, COA and specification documents, and with information on packaging and logistics for GLUCONO-DELTA-LACTONE GDL. For grade recommendations and quotations, please contact Ataman Kimya.
FREQUENTLY ASKED QUESTIONS ABOUT GLUCONO-DELTA-LACTONE GDL
Is GLUCONO-DELTA-LACTONE GDL an acid?
Not as a dry powder. D-glucono-1,5-lactone is a neutral cyclic ester, it becomes acidic only when it hydrolyses in water to gluconic acid.
How long does GLUCONO-DELTA-LACTONE GDL take to acidify?
It depends on temperature, concentration and the buffering of the system. In a 1 % water solution at room temperature, most of the pH drop happens within about two hours, in hot soy milk or during cooking it is much faster.
Is GLUCONO-DELTA-LACTONE GDL the same as gluconolactone?
Yes. Gluconolactone is the INCI and USP name of GLUCONO-DELTA-LACTONE GDL, E575 is its food additive number.
Is GLUCONO-DELTA-LACTONE GDL the same as glucuronolactone?
No. Glucuronolactone is a lactone of glucuronic acid and a different substance with a different CAS number.
Why do tofu makers choose GLUCONO-DELTA-LACTONE GDL?
Because GLUCONO-DELTA-LACTONE GDL gives a very smooth, uniform, glossy gel and allows the soy milk to be packed before it sets, which is ideal for silken tofu.
Does GLUCONO-DELTA-LACTONE GDL replace phosphates in baking powder?
GDL can act as the acid component of phosphate-free baking powders together with sodium bicarbonate.
Is GLUCONO-DELTA-LACTONE GDL suitable for vegan, kosher and halal products?
Glucono-delta-lactone is made from plant-derived glucose by fermentation and is generally suitable, certificates for the specific grade are available on request from Ataman Kimya.
Can GLUCONO-DELTA-LACTONE GDL be used in leave-on cosmetics?
Yes. As Gluconolactone, GLUCONO-DELTA-LACTONE GDL is used in leave-on creams, serums and toners as a PHA, chelating and skin-conditioning ingredient. The final pH must be checked after hydrolysis.
Does GLUCONO-DELTA-LACTONE GDL have an acceptable daily intake limit?
Both JECFA and the EU Scientific Committee for Food allocated an ADI "not specified", meaning no numerical limit was considered necessary. Use is still governed by good manufacturing practice and food-category rules.
How should GLUCONO-DELTA-LACTONE GDL be stored?
Dry, tightly closed, at room temperature, away from humidity.
Glucono-delta-lactone GdL – TECHNICAL SUMMARY
Product name: GLUCONO-DELTA-LACTONE GDL
Other names: Gluconolactone, Glucono Delta Lactone, GDL, D-Glucono-1,5-lactone, E575
CAS No: 90-80-2
EC No: 202-016-5
Molecular formula: C6H10O6
Molecular weight: 178.14 g/mol
INCI name: Gluconolactone
Appearance: White crystalline powder, practically odourless
Melting point: approx. 150–160 °C (decomposes)
Water solubility: approx. 59 g/100 mL (hydrolyses to gluconic acid)
pH (1 %): approx. 3.6 initially, approx. 2.5 at equilibrium
Key property: Slow, progressive acid release with mild taste
Main uses: Tofu coagulant, dairy and cheese acidulant, meat curing accelerator, leavening acid, sequestrant, cosmetic PHA and chelating agent
Regulatory: E575 (EU), GRAS 21 CFR 184.1318 (USA), ADI not specified (JECFA, SCF)
Hazard classification: Not classified as hazardous (CLP)
Storage: Dry, tightly closed, approx. 2–30 °C
Glucono-delta-lactone GdL can be sourced from ATAMAN KİMYA. For further information and supply inquiries about GLUCONO-DELTA-LACTONE GDL, please contact ATAMAN KİMYA.
