GLUCONO-DELTA LACTONE
Glucono-delta lactone (GDL) is a cyclic ester of D-gluconic acid used as a multifunctional food additive with roles in curing, leavening, pH control, and sequestration.
What It Is
Glucono-delta lactone (commonly abbreviated GDL) is a white, odorless crystalline powder that functions as a multifunctional food additive. It is the cyclic 1,5-intramolecular ester of D-gluconic acid and is identified chemically by the CAS number 90-80-2. GDL has also been assigned the INS number 575 by the Codex Alimentarius, indicating its recognition in international food additive standards. The compound is known under multiple synonyms, including D-glucono-1,5-lactone and delta-gluconolactone, reflecting minor variations in nomenclature used across regulatory and scientific communities. Functionally, GDL can serve as a curing or pickling agent, flavor enhancer or flavoring agent adjuvant, leavening agent, pH control agent, formulation aid, and sequestrant in food processing. Its multifunctional technical profile enables food manufacturers to address acidity control, texture modification, preservation, and metal ion chelation within complex food systems. The term "glucono-delta lactone" is used interchangeably with gluconolactone in regulatory texts and industrial practice, though all refer to the same chemical entity that slowly hydrolyzes in aqueous environments to gluconic acid, thereby modulating food pH and related functional properties. As an additive, it is typically included in regulatory lists that permit its use under conditions of good manufacturing practice, rather than being subject to fixed maximum use levels.
How It Is Made
The production of glucono-delta lactone generally begins with the oxidation of glucose or a glucose derivative to yield gluconic acid. This oxidation may be carried out with bromine water, nonpathogenic microorganisms, or enzymatic systems such as glucose oxidase derived from safe microbial sources, each of which facilitates the conversion of D-glucose to gluconic acid. The resulting aqueous gluconic acid solution is then subjected to controlled crystallization, which promotes intramolecular esterification to form the cyclic lactone structure characteristic of GDL. The crystalline product is isolated, washed, and dried to meet food-grade additive specifications, such as those outlined in the Codex Combined Compendium of Food Additive Specifications. Quality attributes such as assay purity, moisture content, and particle form are adjusted to comply with pharmacopoeial or food chemical codex standards, ensuring suitability for use across diverse food applications. Because glucono-delta lactone hydrolyzes in water to gluconic acid and related lactones, manufacturers must consider conditions such as temperature, solvent, and pH when producing and formulating the additive to preserve its functional integrity until use.
Why It Is Used In Food
Glucono-delta lactone is incorporated into foods for its ability to deliver controlled acidic functionality and textural effects without imparting strong sourness. As a slow-release acidulant, GDL gradually hydrolyzes to gluconic acid in aqueous systems, gently lowering pH over time and modulating the acidity of food products. This controlled acidification supports technological goals in various food categories, such as promoting protein coagulation in tofu or dairy products, activating chemical leavening systems when paired with baking soda, or stabilizing pH-sensitive ingredients. In meat processing, GDL contributes to curing and pickling by adjusting acidity, which can assist in texture development and microbial stability. Its chelating properties also allow it to bind metal ions that might otherwise catalyze undesirable oxidative reactions, thus preserving product quality. Additionally, GDL can act as a formulation aid in baked goods and beverages by influencing water activity, buffering capacity, and overall sensory profile. The broad functional profile of glucono-delta lactone makes it a flexible tool for food technologists seeking to fine-tune product characteristics within the constraints of good manufacturing practice.
Adi Example Calculation
Because glucono-delta lactone has an ADI designation that is not numerically specified by expert committees, it is not appropriate to perform a typical ADI example calculation using a numeric daily intake threshold. Instead, examples of ADI calculations are generally framed in contexts where an ADI is defined; in such cases, a hypothetical daily additive intake would be divided by body weight to assess whether exposures remain below the numeric ADI value established by regulators.
Safety And Health Research
Safety evaluations conducted by international expert bodies such as the Joint FAO/WHO Expert Committee on Food Additives have assessed glucono-delta lactone and related gluconates, concluding that it hydrolyzes to gluconic acid, which is an intermediate in normal glucose metabolism. Based on available biochemical, animal, and limited human data, the committee established that a specific acceptable daily intake did not need to be specified, a designation often applied when dietary exposure is not of concern at customary use levels and the compound is metabolized through known pathways. Long-term animal studies reported no evidence of carcinogenicity or teratogenicity at levels tested, and acute oral toxicity values tend to be high relative to typical food exposures, indicating low intrinsic toxicity in conventional use contexts. While GDL’s safety profile supports its regulatory approvals, research continues to monitor emerging data related to digestion, metabolism, and the functional impacts of additive use, ensuring that decisions remain grounded in established toxicological principles.
Regulatory Status Worldwide
In the United States, glucono-delta lactone is affirmed for use in food under the Code of Federal Regulations at 21 CFR 184.1318, where it is described along with its preparation and permitted conditions of use under current good manufacturing practice. This designation reflects the FDA’s recognition of the safety and utility of GDL as a direct food additive without specific numeric use limits when employed appropriately. Internationally, the Codex Alimentarius includes glucono-delta lactone in its General Standard for Food Additives (GSFA), assigning it INS number 575 and listing it in Table 3 for use in dairy and other food categories under the conditions of good manufacturing practice. In the European Union, GDL is authorized as food additive E575 under Commission Regulation (EU) No 231/2012, categorized among additives other than colours and sweeteners and authorized generally with a "quantum satis" use principle, meaning it may be used as needed within good manufacturing practice. Regulatory authorities may periodically review available data and solicit additional information as part of re-evaluation processes to ensure continued safe use.
Taste And Functional Properties
Glucono-delta lactone is characterized by a mild, slightly sweet taste in its pure form and does not exhibit strong sourness until it hydrolyzes to gluconic acid in solution. This gradual acid release distinguishes it from more potent acidulants such as citric or lactic acid, allowing formulators to adjust flavor profiles subtly without overwhelming the palate. Functional properties of GDL include high water solubility and stability in dry blends, making it suitable for inclusion in powdered mixes for bakery and beverage applications. Upon hydration, GDL dissolves and progressively converts to gluconic acid, imposing a controlled pH decline that can influence protein denaturation, gelation, and microbial behavior in foods. Its sequestrant activity, arising from the gluconate anion’s ability to chelate divalent metal ions, contributes to improved texture and color stability in products where metal ions could catalyze oxidative changes. These combined sensory and functional properties allow GDL to influence food structure, flavor, and shelf-life attributes in a range of processed foods.
Acceptable Daily Intake Explained
Acceptable daily intake (ADI) is a risk assessment concept used by regulatory bodies to indicate the amount of a substance that can be consumed daily over a lifetime without appreciable health risk, expressed relative to body weight. For substances that are rapidly metabolized to constituents of normal metabolic pathways and exhibit low toxicity at levels far above human exposure, expert committees may assign an ADI "not specified," meaning that a numerical limit is not needed because the available data do not indicate concern at typical intake levels. In the case of glucono-delta lactone, evaluations by international bodies have deemed it safe enough that a specific numeric ADI was not required, reflecting its metabolic fate to gluconic acid and the absence of adverse effects at exposures relevant to food use.
Comparison With Similar Additives
When comparing glucono-delta lactone with other food acidulants and functional additives, some differences in sensory and functional profiles emerge. Citric acid is a stronger acidulant with a sharp sour taste and rapid pH-lowering effect, whereas GDL’s slow hydrolysis provides milder acidification and subtler flavor changes. Lactic acid, another acidulant, offers distinct flavor notes and antimicrobial properties, but it acts directly without requiring hydrolysis, resulting in faster pH adjustment. Other sequestrants like EDTA function primarily by chelating metal ions with high affinity but do not contribute meaningful acidification or textural influence, highlighting GDL’s multifunctional role in both pH modulation and metal ion binding. These comparisons help formulators choose the most suitable additive based on desired sensory impact and technical function.
Common Food Applications Narrative
Glucono-delta lactone is widely used in food applications where precise control over acidity, texture, and formulation performance is desired. In traditional soy-based products, GDL is often used as a coagulant to produce silken tofu with a uniform, smooth texture, benefiting from its gradual acidification to encourage even protein network formation. In the bakery sector, it functions as a component of chemical leavening systems, providing a delayed acid release that supports carbon dioxide evolution and contributes to desirable crumb structure in cakes, quick breads, and other leavened goods. Processed meats such as cured sausages and hams can incorporate GDL to adjust pH for curing efficacy while contributing to color and flavor stability through its chelating properties. Dairy products such as yogurts and certain cheeses leverage GDL’s acidification to achieve consistent protein coagulation and tailored sensory attributes. Beverage formulations and dressings may also include GDL to fine-tune acidity without imparting overly tart flavor, supporting balanced taste profiles in fruit juices, flavored waters, and ready-to-drink beverages. Across these applications, manufacturers rely on GDL’s slow-release acidification, sequestration of metal ions, and compatibility with other ingredients to deliver functional performance consistent with good manufacturing practice.
Safety & Regulations
FDA
- Approved: True
- Regulation: 21 CFR 184.1318
EFSA
- Notes: EFSA authorizes GDL as E575 under quantum satis but does not provide a numeric ADI in the d sources
- Approved: True
- E Number: E575
JECFA
- Notes: Group ADI not specified per JECFA evaluations in the d sources
- Ins Number: 575
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