IngredientsEthyl maltol is known by the systematic IUPAC name 2-ethyl-3-hydroxy-4H-pyran-4-one, and is also recorded under several synonyms including 3-hydroxy-2-ethyl-4-pyrone, 2-ethylpyromeconic acid, 3-hydroxy-2-ethyl-γ-pyrone, and the trade names Veltol Plus. Its molecular formula is C7H8O3 and it carries PubChem CID 21059. Its CAS Registry Number is 4940-11-8, and in the flavor industry it is assigned FEMA number 3487.
Ethyl maltol belongs to the γ-pyrone class of compounds, sharing a characteristic caramel-like and fruity aromatic profile with its parent compound maltol. It is an analogue of maltol (also called methyl maltol), obtained by replacing the methyl group in the maltol molecule with an ethyl group.
Ethyl maltol is a white, crystalline powder with a unique odor and a sweet taste that resembles fruit. Its melting point is 90°C, and it is sparingly soluble in water and propylene glycol but soluble in alcohol and chloroform.
The flavor and aroma intensity of ethyl maltol is approximately 3 to 4 times stronger than that of maltol, and it is more volatile due to the slight difference in molecular structure; to achieve the same flavor enhancement effect, the dosage of ethyl maltol required is only one-third to one-fourth that of maltol. Ethyl maltol has a stronger sweet fruity taste with less caramel smell compared to maltol.
Ethyl maltol is a key food flavor compound characterized by caramel-like and fruity aromas and strong flavor-enhancing capacity. Traditionally it was primarily considered a synthetic additive; however, recent analytical evidence has confirmed that it also occurs naturally. Recent reviews systematically summarize its natural occurrence and concentration ranges, including major formation pathways such as the Maillard reaction and microbial metabolism, and its direct and flavor-enhancing roles in key products such as tea, soy sauce, coffee, alcoholic beverages, and chocolate.
Ethyl maltol is a synthetic homologue of maltol that contributes to the fragrance of commercial products such as cereals, breads, malt beverages, coffee, soybeans, and chocolate milk. Its precursor maltol was first discovered in the early 20th century, naturally occurring in roasted malt, larch bark, and the thermal degradation products of carbohydrates.
Ethyl maltol functions as a flavor and fragrance enhancer in foods, especially baked goods, beverages, and synthetic berry and citrus flavorings; it also minimizes undesirable flavors in tobacco products, cough syrups, vitamins, cosmetics, and saccharin-containing products. Both maltol and ethyl maltol are used as the basic components of complex flavors and fragrances, and are commonly employed in the preparation of many fruit flavors, including citrus orange, pear, pineapple, cherry, grape, mango, apple, and coconut.
Ethyl maltol is widely used as an aromatic additive in food, beverages, pharmaceutical products, and is also a common additive to vaping fluid used in electronic cigarettes. A study reported that ethyl maltol is found in 80% of the vaping fluid products surveyed.
Although ethyl maltol is today widely recognized for its role in gourmand perfumery and food flavoring, its history traces a rich intersection between natural chemistry and 20th-century industrial synthesis. The molecule's precursor, maltol (3-hydroxy-2-methyl-4-pyrone), was first discovered in the early 20th century, naturally occurring in roasted malt, larch bark, and the thermal degradation products of carbohydrates. Maltol was formally described in early food chemistry literature as contributing to the crust-like, caramelized aroma of freshly baked goods.
The demand for maltol eventually surpassed the capacity to isolate it from natural sources, and so maltol is now produced synthetically. A related compound, ethyl maltol, was introduced to the food industry several years after the shift to chemical production of maltol. When compared to maltol, it has qualitatively similar yet much improved flavor- and aroma-enhancing capabilities. The synthesis of ethyl maltol—2-ethyl-3-hydroxy-4-pyrone—was achieved in the mid-to-late 20th century, likely by industrial chemists seeking more potent flavoring agents.
It bears emphasis that ethyl maltol as an isolated, named compound has no documented history of traditional medicinal use in classical herbal systems. Its role in traditional and historical contexts is entirely as a flavor constituent of thermally processed foods (breads, roasted grains, caramelized sugars) rather than as a deliberately administered botanical preparation.
Ethyl maltol can be commercially produced by chemical synthesis, generally through a manufacturing process involving Grignard reagent preparation, Grignard reaction, hydrolysis, chlorination, and rearrangement reaction. It is obtained by chemical synthesis. Several syntheses have been developed for its preparation. In one one-pot process, for example, ethylfurfuryl alcohol is treated with halogen to give 4-halo-6-hydroxy-2-ethyl-2H-pyran-3(6H)-one, which need not be isolated.
The pyrone 3-hydroxy-2-ethyl-4-pyrone (ethyl maltol) chelates iron with high affinity and selectivity. The resulting 1:3 (metal-ligand) complexes, being neutral, are able to partition readily across cell membranes and thus may facilitate iron transport across the intestinal wall.
The alpha-ketohydroxy heteroaromatic chelators, including maltol and its analogues, represent a class of phytochelators with high affinity for iron. These alpha-ketohydroxy chelators appear to be important phytochelators affecting metabolic pathways including iron absorption, iron excretion, and iron-catalyzed free radical reactions.
In previous studies, ethyl maltol was confirmed to combine with Fe3+ in different ratios, namely 1:1, 1:2, and 1:3. This property places ethyl maltol firmly within the category of bidentate hydroxypyrone chelating agents, sharing structural and functional similarities with deferiprone (L1) and kojic acid. The maltol iron complex is used for increasing iron absorption.
Considering that ethyl maltol facilitates heavy metal transport across plasma membranes, and that heavy metals have been detected in aerosols generated from e-cigarettes, research has examined whether ethyl maltol enhances heavy metal-mediated toxicity. Several metals released from e-cigarettes, including iron and copper, are potentially cytotoxic due to their ability to catalyze the generation of reactive oxygen species (ROS).
When orally administered, ethyl maltol is rapidly and extensively absorbed. Elimination is also extensive and rapid, involving conjugation as the glucuronide and ethereal sulphate, and excretion in the urine to the extent of 65–70% within 24 hours.
The excretion rate of ethyl maltol was measured in the dog by both oral and intravenous routes of administration. Beagle dogs fed 200 mg/kg of ethyl maltol daily for 99 days had urine and feces collected after days 98 and 99. Urinary excretion of the unchanged test substance averaged 0.13% of the daily dose, while excretion of the sulfate and glucuronide conjugates averaged 64.0%. Similarly, 64.5% of a single intravenous 10 mg/kg dose of ethyl maltol was excreted as the conjugates within 24 hours and 66.3% within 72 hours.
Rate studies after intravenous dosage indicated that the bulk (86%) of the recovered conjugates was excreted within 6 hours. Results of experiments with dogs indicate that maltol and ethyl maltol are rapidly and efficiently absorbed following oral administration and converted to the glucuronide conjugate; similar processes probably occur in humans.
Collectively, authoritative reviews demonstrate that ethyl maltol is rapidly absorbed and metabolized, leading to quick excretion from the body primarily as glucuronic acid conjugates. It has a low potential for bioaccumulation and has consistently shown no significant adverse effects in long-term studies at doses considerably higher than typical human dietary exposure.
Considering that ethyl maltol is highly lipophilic and volatile, it could easily pass through the blood–brain barrier and enter the brain, which raises the possibility that exposure to ethyl maltol may be neurotoxic by modifying intracellular iron homeostasis.
Evidence Type: Animal (rodent) studies; no published human clinical trials exist specifically for ethyl maltol as an isolated iron absorption enhancer.
The pyrones maltol and ethyl maltol chelate iron with high affinity and selectivity. The resulting 1:3 neutral metal–ligand complexes are able to partition readily across cell membranes, facilitating iron transport across the intestinal wall. Absorption of radioactive iron (59Fe) in the presence of these pyrones was investigated in male rats 1, 2, 4, and 6 hours after intraduodenal administration of a 7-microgram dose and compared with that of 59Fe given as the sulphate, gluconate, fumarate, or complexed to EDTA.
Total body absorption of 59Fe was significantly higher from the pyrones than from the other four preparations. Over the dose range 0.7–700 micrograms, the proportion of 59Fe absorbed from both iron maltol and iron sulphate decreased with increasing dose. Enhanced 59Fe uptake from maltol was evident at 0.7–70 micrograms but not at 700 micrograms, suggesting that use of these pyrones will not result in iron overload.
Evidence strength: The primary data are rodent studies. Translation to clinical use has been explored more extensively for ferric maltol (the structurally related maltol-iron complex used in approved iron-deficiency treatments) rather than for ethyl maltol itself. No standalone human supplementation trials for ethyl maltol as an iron enhancer have been identified in authoritative sources.
Ethyl maltol is a key food flavor compound with a strong flavor-enhancing capacity. Its primary established application is in food technology, where it functions as a flavor potentiator rather than a true sweetener. Ethyl maltol is commonly used as a fruity sweet flavor, although it is not a real sweetener. Its roles include functioning as a flavor and fragrance enhancer in baked goods, beverages, and synthetic berry and citrus flavorings, and minimizing undesirable flavors in tobacco products, cough syrups, vitamins, cosmetics, and saccharin-containing products.
Evidence strength: The flavor-enhancement efficacy of ethyl maltol in food systems is well-established and forms the basis of its broad regulatory approval. These effects are empirically validated through food science rather than clinical intervention trials.
Evidence Type: In vitro cell culture studies. No clinical data in humans.
Ethyl maltol has been reported to bind iron and facilitate iron transport. Since it is membrane permeable, researchers investigated its potential to disrupt intracellular iron homeostasis. Ethyl maltol increased the labile iron pool in SH-SY5Y neuroblastoma cells and increased iron-responsive protein activity using a reporter assay in HEK293 cells. It induced the expression of transferrin receptor 1 mRNA and decreased the expression of ferritin light chain protein in SH-SY5Y cells.
Ethyl maltol treatment decreased cell viability and increased DNA damage. It also increased the level of phosphorylated p53 and the expression of p53-regulated genes, p21 and 14-3-3σ. Expression of amyloid precursor protein (APP) attenuated the effects of ethyl maltol on viability, DNA damage, and the p53 response.
Iron is required in multiple cellular functions including mitochondrial respiration, chromatin modeling, and xenobiotic metabolism. Because the brain is an energy-demanding organ, iron homeostasis is especially important. When iron homeostasis is disrupted, enzymes requiring iron might not be active and reduced iron could cause oxidative damage by generating reactive oxygen species. Iron and other metals are thought to be involved in the pathologies of Alzheimer's and Parkinson's diseases.
Evidence strength: Preliminary, in vitro only. These mechanistic findings have not been confirmed in human studies. Concentrations used in cell culture experiments may not reflect typical dietary exposures.
Evidence Type: In vitro studies in lung epithelial cell lines.
Co-exposure to ethyl maltol and copper causes apoptosis in lung epithelial cells, DNA damage in lung epithelial cells, and increased oxidative stress. Considering that ethyl maltol facilitates heavy metal transport across plasma membranes, and that heavy metals have been detected in aerosols generated from e-cigarettes, the study examined whether ethyl maltol enhances heavy metal-mediated toxicity. A decrease in viability was observed in the Calu-6 and A549 lung epithelial cell lines co-exposed to ethyl maltol and copper.
Artificial sweeteners used in flavorants, such as ethyl maltol, may enhance the ability of the leached metals in vaping aerosols to be taken up into the cells of the body.
Evidence strength: Preliminary; in vitro. The extent to which these findings translate to real-world human exposures via food or vaping requires further investigation.
Evidence Type: Animal studies; computational (in silico) modeling. No human clinical data.
Ethyl maltol is a ubiquitous synthetic flavor enhancer. Despite its widespread use in foods, beverages, and electronic cigarettes, its long-term cardiovascular safety remains unevaluated in humans. One recent study employed an integrative strategy commencing with network toxicology and machine learning to identify pivotal molecular targets. The interaction between ethyl maltol and the key target was scrutinized via molecular docking and dynamics simulations, with cardiovascular toxicity subsequently validated through in vivo and in vitro experiments, incorporating transcriptomic and single-cell RNA sequencing analyses.
HMOX1 was identified as the central target. Molecular simulations confirmed stable binding between ethyl maltol and HMOX1. In mice, ethyl maltol exposure at doses of 5, 10, and 20 mg/kg induced anemia, platelet activation, reduced hindlimb perfusion, and impaired endothelium-dependent vasodilation, concomitant with upregulated vascular adhesion molecules.
Evidence strength: Preliminary; animal and computational. These findings are from a 2026 publication and have not yet been replicated or extended to human populations. The doses used in mice may not correspond to typical human dietary exposures via food additive use.
Evidence Type: In vitro studies using immune cell lines.
High amounts of reactive oxygen species were elicited by ethyl maltol in cell line studies. Naïve THP-1 cells (a human macrophage model) produced significantly elevated levels of IL-1β, IL-8, and TNF-α when exposed to ethyl maltol. Activated THP-1 cells released increased IL-1β and TNF-α when exposed to ethyl maltol.
Evidence strength: Preliminary, in vitro only. No human immunological data on dietary ethyl maltol exposure exist.
Ethyl maltol has been found in some commercial e-cigarette refill fluids at levels reportedly 100 times their cytotoxic concentration. Ethyl maltol, among numerous other flavorings, has been effectively transferred to e-cigarette aerosols that may cause cytotoxicity, mostly to the respiratory system.
Evidence strength: These concerns are generated primarily from in vitro cytotoxicity assays using concentrations found in e-cigarette fluids, which are different from the much lower concentrations encountered in typical food use. The neurotoxic potential of ethyl maltol at food-additive concentrations in humans has not been established.
Ethyl maltol is specifically approved by the FDA as a synthetic flavoring substance and adjuvant under 21 CFR 172.515. This classification means it is considered safe for its intended use when used in accordance with good manufacturing practices, not exceeding the minimum quantity required to achieve its intended effect.
Ethyl maltol (FL-no: 07.047) is authorized for use as a flavoring agent in the EU according to Annex I to Regulation (EU) No 1334/2008. Its safety as a flavoring agent was re-evaluated by the EFSA in 2010. EFSA established the same conclusion as JECFA: "No safety concern at estimated level of intake as flavouring substance," based on the Maximised Survey-derived Daily Intake (MSDI) approach. An Acceptable Daily Intake (ADI) of 0–2 mg/kg body weight was set by JECFA.
JECFA has reviewed ethyl maltol multiple times, including evaluations in their 11th, 14th, 19th, 23rd, 24th, and 46th meetings. Based on comprehensive toxicological studies including acute, short-term, and long-term toxicity, as well as genotoxicity, carcinogenicity, and reproductive toxicity studies, JECFA established an Acceptable Daily Intake (ADI) for ethyl maltol of 0–2 mg/kg body weight in 1977, which has been consistently re-affirmed.
The EFSA panel concluded that there was no genotoxic concern for ethyl maltol and confirmed its safety at estimated dietary exposures, which are well below the ADI set by JECFA, for its specified uses as a flavoring agent across various food categories.
JECFA generally concludes that ethyl maltol exhibits low oral toxicity and is rapidly absorbed, metabolized, and excreted primarily via urine, minimizing the potential for accumulation. Authoritative reviews demonstrate that ethyl maltol is rapidly absorbed and metabolized, leading to quick excretion from the body primarily as glucuronic acid conjugates. It has a low potential for bioaccumulation and has consistently shown no significant adverse effects in long-term studies at doses considerably higher than typical human dietary exposure.
Although ethyl maltol enhances the scent of foods, a high dietary intake may lead to headaches, nausea, and vomiting and could affect liver and kidney functions, as reported in animal studies. These effects are documented at doses substantially exceeding the approved ADI.
Ethyl maltol combines with Fe3+ in different ratios (1:1, 1:2, and 1:3). In the process of preparing certain foods (such as the Chinese dish hot-pot, where ethyl maltol-containing flavor preparations contact iron cookware), ethyl maltol inevitably comes in contact with iron to form kinetically labile iron complexes. In the process of making hot-pot, the ethyl maltol reacts with iron to form iron complexes. Alternative strategies for preparing hot-pot, including the use of non-iron-based cookware, may be warranted to avoid the formation of potentially toxic complexes.
Ethyl maltol is a flavoring agent that falls under the generally recognized as safe category and is added to many commercial e-cigarette vaping fluids, where it has been detected in aerosols. Considering that it facilitates heavy metal transport across plasma membranes, and that heavy metals have been detected in aerosols generated from e-cigarettes, concern has been raised about whether ethyl maltol enhances heavy metal-mediated toxicity.
Ethyl maltol has been found in some commercial e-cigarette refill fluids at levels reportedly 100 times their cytotoxic concentration. Some JUUL flavor pods have been found to contain sufficiently high concentrations of flavor chemicals including ethyl maltol that are high enough to be cytotoxic in acute in vitro assays, emphasizing the need to determine whether such products lead to adverse health effects with chronic use.
EFSA has conducted a thorough review of all available toxicological data, including in-depth assessment of genotoxicity potential and extensive dietary exposure assessments for the European population. The EFSA panel concluded that there was no genotoxic concern for ethyl maltol and that estimated dietary exposures were well within safe limits. However, ethyl maltol is a representative of the 1,2-dicarbonyl class of chemicals. The total daily human doses of mutagenic 1,2-dicarbonyl compounds are likely to be much greater than estimates based on known levels of maltol, ethyl maltol, and diacetyl; other 1,2-dicarbonyl compounds such as intermediates in enzymatic and nonenzymatic browning reactions in foods are weakly mutagenic in the Ames test.
Ethyl maltol increases the labile iron pool in cells and induces the expression of transferrin receptor 1 mRNA while decreasing the expression of ferritin light chain protein, which are hallmarks of cellular iron deficiency signaling — paradoxically, despite facilitating iron entry. This finding from cell culture suggests that ethyl maltol may alter intracellular iron distribution in ways that decouple extracellular iron availability from intracellular iron storage, though the physiological relevance at dietary exposure levels remains unknown.
The body of scientific literature on ethyl maltol can be characterized as follows:
Health conditions that Ethyl maltol may help support.
Body systems that Ethyl maltol may help support.
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