BUTYL ETHYL DISULFIDE

CAS: 63986-03-8 FLAVORING AGENT OR ADJUVANT

**Butyl Ethyl Disulfide** is an organosulfur compound used primarily as a flavoring agent or adjuvant, recognized for its sulfurous aroma and technical function in food flavor systems.

What It Is

Butyl Ethyl Disulfide is a synthetic organosulfur compound characterized by a chemical structure in which a butyl group and an ethyl group are linked by a disulfide bond. The substance is identified by the Chemical Abstracts Service Registry Number CAS 63986-03-8, and it is used in the food industry primarily as a flavoring agent or adjuvant that contributes distinctive sensory properties to food products. While it is not a widely recognized common food ingredient like salt or sugar, it has been evaluated for safety in the context of food flavoring use and holds identifiers such as a FEMA GRAS number (4027) and a JECFA number (1698) in international flavor additive databases. These identifiers reflect its classification within organized flavoring evaluation programs and its technical function as a component that can modify or enhance the sensory profile of foods. Organosulfur compounds like butyl ethyl disulfide are a broad class of molecules valued in food science for their impact on aroma and taste. Their characteristic sulfurous notes are often desirable in savory or umami-rich flavor profiles, and they can mimic or enhance natural flavors associated with foods such as cooked onions, garlic, or other sulfur-containing natural ingredients. This flavoring agent is typically used in very low concentrations, consistent with the practice for potent flavoring substances, and is part of flavor libraries maintained by regulatory or industry groups. In food science terminology, the technical function of butyl ethyl disulfide falls under the category of 'flavoring agent or adjuvant.' A flavoring agent is an ingredient added to food primarily to impart or modify taste and aroma, while an adjuvant might support or synergize with other flavor components to achieve a desired sensory effect. Though relatively specialized compared with staple ingredients, substances like butyl ethyl disulfide are critical tools for flavorists and food technologists working to fine-tune complex flavor systems.

How It Is Made

The manufacturing or preparation of butyl ethyl disulfide typically involves organic synthesis techniques centered on introducing a disulfide linkage between a butyl moiety and an ethyl moiety. Organosulfur compounds such as this are often prepared using controlled reactions between thiol derivatives and sulfur-containing reagents, where the oxidative coupling of thiols leads to disulfide formation. In practical industrial settings, precursor thiols like butanethiol and ethanethiol may be combined under conditions that favor disulfide bond formation, such as controlled oxidation in the presence of catalysts or specific oxidizing agents. The resulting compound is a clear, colorless to pale yellow liquid with a characteristic sulfurous odor. After synthesis, the product is usually purified by techniques such as distillation or solvent extraction to achieve the desired concentration and purity levels appropriate for flavoring use. Purification is critical because trace levels of impurities can significantly influence the sensory properties of a flavoring substance. Quality control measures during production often involve analytical techniques such as gas chromatography-mass spectrometry (GC-MS) to confirm compound identity and assess purity. Because butyl ethyl disulfide is used at low levels in formulated flavor products, specifications for purity and allowable impurities are defined by industry standards and regulatory evaluations. Industry and regulatory sources list typical specifications and identification data that support quality assurance for compounds used in flavor contexts. In addition to synthetic routes, the general methodology for producing organosulfur flavor compounds emphasizes the importance of maintaining rigorous controls over reaction conditions, raw materials, and handling procedures. The processes are designed to minimize undesired byproducts and to ensure that the compound meets safety and performance expectations for its role in food applications. As with many synthetic flavoring agents, the synthesis of butyl ethyl disulfide is carried out by chemical manufacturers with expertise in sulfur chemistry and flavor raw material production.

Why It Is Used In Food

Butyl Ethyl Disulfide is included in food formulations because of its distinctive sensory properties and its ability to modulate flavor profiles. The compound’s sulfurous aroma and taste-contributing characteristics make it valuable in savory or umami-rich applications where subtle but impactful notes are desirable. Unlike foundational ingredients such as sugars or salts, specialized flavoring agents like butyl ethyl disulfide are chosen for their ability to enhance, balance, or replicate specific flavor dimensions, particularly in products where complex aroma profiles are essential. Flavorists and food developers often combine multiple flavoring agents to achieve depth and character in final food products. For example, sulfur-containing flavor compounds can contribute to the perception of cooked or roasted notes, and they find utility in applications that benefit from such profiles. In these contexts, butyl ethyl disulfide may be used alongside other organosulfur compounds or flavor building blocks to create balanced and consumer-accepted tastes. The use of butyl ethyl disulfide is generally at very low concentrations, consistent with the potency of sulfurous flavoring chemicals. Small adjustments in these levels can have a disproportionately large effect on the overall sensory impression, so precise formulation and dosing are hallmarks of its use in food technology. This targeted application supports the broader purpose of enhancing and diversifying flavor without overwhelming the primary tastes or aromas that define a product. Manufacturers consider functional performance characteristics such as volatility, stability under processing conditions, and compatibility with other flavor components when selecting flavoring agents. Butyl ethyl disulfide’s physicochemical properties make it suitable for certain formulations that will undergo thermal processing or require stable performance over shelf life. In summary, its use in food is driven by its capability to contribute recognizable and desired flavor notes that support specific sensory goals in culinary applications.

Adi Example Calculation

Because butyl ethyl disulfide does not have a defined numeric ADI from regulatory evaluations, an illustrative calculation of daily intake relative to a hypothetical ADI is not provided here. Instead, it is important to understand that typical use levels in flavor applications are very low. In general, illustrative calculations for flavoring agents involve estimating the concentration of the compound in a prepared food, multiplying by the amount of food consumed, and dividing by body weight to estimate exposure in mg/kg bw/day. If a numeric ADI existed, this estimate would be compared against that value to gauge safety margins. However, in this case, regulatory evaluation has concluded no safety concern at current usage levels without a numeric ADI, and users should interpret exposure in the context of that conclusion rather than a formal calculation.

Safety And Health Research

Safety assessments for flavoring agents like butyl ethyl disulfide focus on understanding potential toxicological effects relative to expected human exposure levels. Expert bodies such as JECFA evaluate available toxicological data, including studies on metabolism, acute toxicity, and other endpoints relevant to consumer safety. For butyl ethyl disulfide, the conclusion of "no safety concern at current levels of intake" reflects a weight-of‑evidence assessment in which exposure from intended use is low relative to thresholds for adverse effects. This judgment does not imply that the compound is inherently risk-free at any level, but rather that typical usage scenarios in food do not pose identifiable safety concerns based on existing data. Flavoring agents are typically evaluated within comprehensive frameworks that consider chemical structure, expected exposure, and available toxicology studies. Evaluators also review structure-function relationships with similar compounds, in vitro and in vivo data when available, and potential metabolic pathways. These assessments aim to characterize hazard potential and to place likely consumer exposure in context. When expert panels conclude that a compound is of no safety concern under intended uses, it suggests that standard flavoring use does not pose measurable risks based on current evidence. It is also important to note that safety research continues as part of broader regulatory science activities. New data or insights can lead to reevaluation of existing compounds, updated specifications, or refined usage guidelines. Researchers and regulators monitor emerging scientific findings to ensure that flavoring agents remain consistent with evolving understanding of human health and exposure science.

Regulatory Status Worldwide

Butyl ethyl disulfide has been evaluated for safety and use in food flavoring contexts by recognized expert bodies. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) assigned this compound the number 1698 and evaluated its safety in the context of flavoring use. According to the JECFA evaluation, butyl ethyl disulfide has no safety concern at current levels of intake when used as a flavoring agent, reflecting expert assessment of toxicological data and expected exposure in food applications. The evaluation is documented in JECFA reports and monographs specific to flavoring agents. The JECFA evaluation does not define a specific acceptable daily intake (ADI) numeric value because it concluded no safety concern under typical uses, rather than specifying a quantified ADI. This type of outcome indicates that established safety margins were sufficient based on available data and expected exposure conditions. Source data from the WHO JECFA database support this conclusion. In the United States, butyl ethyl disulfide is listed in the FDA Substances Added to Food inventory (formerly EAFUS), indicating recognition of its use as a flavoring ingredient. The FDA inventory entry identifies the compound by its CAS number, technical effect (flavoring agent or adjuvant), and associated FEMA GRAS status based on industry evaluations. However, the FDA does not assign an explicit regulation like a CFR section for direct approval of individual flavoring agents, and specific regulatory allowances are based on inventory listings and expert panel determinations. Internationally, flavor additive information maintained by industry groups like the Flavor and Extract Manufacturers Association (FEMA) reflects GRAS assessments (e.g., FEMA GRAS number 4027 for this compound). The IOFI Global Reference List documents evaluations of butyl ethyl disulfide reporting "evaluated - no safety concern" status and associated flavor additive identifiers. Regulatory environments in various regions may require compliance with local labeling and usage restrictions, but the existing evaluations provide a framework for understanding how authorities consider the compound in food flavoring applications.

Taste And Functional Properties

Butyl Ethyl Disulfide exhibits taste and functional properties typical of sulfur-containing organosulfur compounds. In sensory terms, it is associated with a sulfurous odor reminiscent of cooked onion or garlic notes when used at very low concentrations in flavor systems, and this olfactory contribution is a key reason for its inclusion in specific food flavor profiles. Such sensory attributes are powerful—they can influence perceived complexity and enhance depth when combined with other flavor components. From a functional perspective, the physicochemical traits of butyl ethyl disulfide influence how it behaves in formulations. The compound is generally soluble in nonpolar solvents and may exhibit limited solubility in aqueous food matrices, meaning it is often incorporated into emulsions, encapsulated systems, or blended with carriers that facilitate dispersion. Its volatility and thermal stability are also important considerations; a flavoring agent must retain its sensory impact through processing steps such as heating or drying if present in finished products. The presence of the disulfide bond influences both aroma potency and chemical reactivity. Organosulfur compounds tend to have lower sensory thresholds compared with many non-sulfur flavoring agents, meaning that only trace amounts are needed to elicit perceptible changes in aroma and flavor. This property requires careful formulation: too much can lead to overpowering off-notes, while too little may fail to deliver the intended sensory enhancement. Butyl Ethyl Disulfide’s functional behavior also includes interactions with other flavor compounds. In multi-component systems, synergistic effects can arise where the combined sensory outcome is greater than the sum of individual contributions. Flavorists leverage such interactions to achieve balanced and appealing profiles in food products, particularly those seeking savory, roasted, or complex aromatic dimensions.

Acceptable Daily Intake Explained

The concept of an Acceptable Daily Intake (ADI) is a risk assessment tool used by regulatory and expert bodies to quantify a level of daily exposure to a substance that is considered safe over a lifetime without appreciable health risk. For many food additives, ADIs are derived from toxicological studies that identify no-effect levels in animal experiments and then apply safety factors to account for uncertainties when extrapolating to humans. In the case of butyl ethyl disulfide, the JECFA evaluation concluded that there was no safety concern at current intake levels when used as a flavoring agent, and as a result did not define a specific numeric ADI. This outcome means that based on the evidence reviewed and the expected low levels of exposure from typical use, experts did not identify a need to establish a quantitative intake limit. Instead, the compound’s safety under these conditions is inferred from the overall assessment of hazard and exposure. The absence of a numeric ADI in this context should not be interpreted as a recommended intake but rather as a regulatory position that current use patterns pose no safety concern according to available evidence. When an ADI is established for other substances, it is usually expressed in terms of milligrams per kilogram of body weight per day (mg/kg bw/day). Consumers, food scientists, and regulatory authorities use ADIs to guide formulation practices and to interpret safety margins. For compounds without defined ADIs because of determinations of no safety concern at expected exposure levels, the focus remains on maintaining use within typical industry practices.

Comparison With Similar Additives

Butyl ethyl disulfide can be compared with other sulfur‑containing flavoring agents that impart similar savory or umami sensory characteristics. For example, diethyl disulfide and dimethyl trisulfide are other organosulfur compounds used or encountered in flavor science. Each of these compounds has distinct sensory profiles and volatility properties that influence how they contribute to overall flavor. Diethyl disulfide has a characteristic sulfurous odor and is also used in select flavoring contexts. Dimethyl trisulfide, another organosulfur compound, exhibits a potent aroma reminiscent of cooked cabbage or onion and is naturally present in some foods. The comparison among these compounds highlights differences in sensory intensity, volatility, and functional behavior. Butyl ethyl disulfide’s sensory profile may be more suited to certain savory applications, while other organosulfur compounds are chosen for specific notes or interactions within complex flavor systems. Regulatory evaluations of these substances also vary; some may have specific ADIs defined, others may be classified as having no safety concern at typical usage levels, and still others may be subject to more restrictive guidance depending on their toxicological data and exposure contexts. In all cases, flavorists and regulatory professionals consider both sensory performance and safety assessments to select appropriate flavoring agents.

Common Food Applications Narrative

In practical food applications, butyl ethyl disulfide is most often encountered in contexts where nuanced, savory, or umami flavor profiles are critical. These include a spectrum of processed foods that benefit from carefully developed aroma and taste characteristics. For example, savory snacks may incorporate flavor enhancers to mimic roasted or caramelized notes that complement the primary ingredients. In such uses, sulfurous components like butyl ethyl disulfide contribute to a richer sensory character that enhances consumer appeal. Another area where these flavoring agents are deployed is in ready-to-eat meals and prepared sauces. In these products, multiple flavor layers are combined to reproduce the complexity of homemade dishes. The careful calibration of sulfur-bearing compounds helps achieve roasted, aromatic, or cooked vegetable nuances that resonate with familiar culinary experiences. Similarly, soups, bouillons, and broth concentrates may contain such compounds to bolster depth and savory impressions without needing extensive amounts of base ingredients. Flavorists also utilize butyl ethyl disulfide in seasoning blends formulated for meat alternatives or plant-based proteins. In these applications, the strategic inclusion of sulfurous notes can bridge the sensory gap between plant-derived ingredients and the expected taste profiles of traditional meat products. By tuning flavor building blocks, manufacturers aim to deliver products with sensory richness that matches consumer expectations. It is important to emphasize that usage levels in actual food applications are typically low and carefully controlled. The objective is not to impart a standalone flavor but to support a harmonized sensory experience. Culinary artisans and food technologists work closely with regulatory guidelines and sensory science to integrate specialized flavoring agents into products that resonate with target taste profiles while meeting safety and labeling requirements.

Safety & Regulations

FDA

  • Notes: FDA does not assign a specific CFR regulation number for this flavoring; it is listed in the Substances Added to Food inventory with FEMA GRAS context.

EFSA

  • Notes: No explicit EFSA numeric ADI was identified in authoritative evaluations; status is based on general evaluations.

JECFA

  • Notes: JECFA evaluation concluded no safety concern at current intake levels; no numeric ADI assigned.

Sources

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