1,3-BUTANEDITHIOL
1,3-Butanedithiol is an organosulfur compound with a potent alliaceous odor that is used as a flavoring agent in food products under conditions of intended use. It has been evaluated internationally for safety by JECFA and is used for its savory/garlic-meaty sensory profile.
What It Is
1,3-Butanedithiol, also known by the systematic names butane-1,3-dithiol and 1,3-dimercaptobutane, is an organosulfur compound characterized by a four-carbon chain bearing two thiol (-SH) functional groups. The chemical has the CAS Registry Number 24330-52-7 and is recognized for its strong savory and alliaceous sensory attributes. Organosulfur compounds like 1,3-butanedithiol are commonly encountered in nature and in the flavor industry due to their contribution to the characteristic aroma and taste of cooked onions, garlic, and meaty notes. Globally, the compound is used principally as a flavoring agent or adjuvant to enhance or modify the sensory attributes of food products, particularly in savory applications. In terms of class, 1,3-butanedithiol falls under sulfur-containing flavoring substances. Sulfur compounds often have low odor thresholds and contribute strongly to flavor profiles even at minute concentrations. The compound’s sensory description includes garlic-like, sulfurous, and meaty notes, which makes it valuable for flavor formulators seeking to enrich or balance savory flavor profiles in food systems. Its use is part of a broader class of volatile sulfur flavor compounds that interact with human olfactory receptors to produce characteristic aroma impressions. Due to the strength of its odor, technical use levels are typically very low relative to the overall formulation. Understanding what 1,3-butanedithiol is also requires recognizing its role in regulatory frameworks. It is listed in flavor ingredient inventories such as the FEMA Flavor Library as a flavoring substance with an assigned FEMA number, indicating that experts have evaluated its safety under intended conditions of use. Furthermore, international food additive evaluations include its entry in the JECFA database, where it has been assessed for safety with respect to typical intake levels in food. These evaluations are important for ingredient manufacturers and food formulators seeking to ensure compliance with food safety standards in different regions.
How It Is Made
The synthesis of 1,3-butanedithiol is typically accomplished through organic chemistry routes that introduce thiol groups to a butane backbone. While specific production methods are proprietary to manufacturers, general approaches involve the nucleophilic substitution of suitable butane derivatives with sulfur-containing reagents to yield the dithiol product. These processes take place under controlled conditions with catalysts or reagents that favor the formation of thiol functionalities at the desired carbon positions. The thiol groups confer the characteristic chemical reactivity that makes this compound useful in flavor applications. Commercial production of 1,3-butanedithiol requires careful attention to purity because trace impurities or byproducts can dramatically influence odor and flavor quality. Food-grade specifications generally require high purity and adherence to good manufacturing practices (GMP) to minimize contaminants that could impact safety or sensory properties. Organosulfur compounds in general are sensitive to oxidation and other degradation pathways, so manufacturing and storage conditions are optimized to preserve the integrity of the compound until it is incorporated into flavor formulations. Quality control for flavor ingredients like 1,3-butanedithiol often involves analytical chemistry techniques such as gas chromatography coupled with mass spectrometry (GC-MS) to confirm identity, purity, and absence of unwanted residues. Producers may also use sensory evaluation panels to confirm that the aroma profile meets specifications for intended flavor applications. Specifications may be guided by international compendia when available or by technical agreements between suppliers and users. Although detailed proprietary synthesis protocols are not publicly disclosed, standard organic chemistry routes for forming thiols from aliphatic precursors are foundational knowledge for flavor chemists and industrial manufacturers.
Why It Is Used In Food
1,3-Butanedithiol is used in food primarily for its potent flavor-enhancing properties. Flavoring agents like this compound are used to impart or accentuate specific sensory notes in complex food matrices. In particular, its alliaceous and meaty odor characteristics make it valuable in savory flavor profiles where garlic, onion, roasted, or cooked notes are desired. Flavor chemists leverage such compounds to achieve targeted sensory effects that complement base ingredients in formulations for soups, sauces, snack foods, and other savory products. Flavor enhancers and adjuvants are distinct from sweeteners or colorants in that they modulate the perception of taste and aroma, often at very low concentrations. Flavor enhancers can also improve the perception of umami or savory qualities, contributing to a more robust overall flavor experience in finished products. Because of the strength of sulfur-containing compounds like 1,3-butanedithiol, formulators use them judiciously, typically at levels that achieve the desired aromatic impact without overwhelming the product’s profile. The intended use of 1,3-butanedithiol in food is tightly linked to sensory outcomes. For example, in savory applications such as meat analogs, bouillon products, and flavored snacks, the compound can be part of a blend that mimics the natural flavors of garlic or roasted onions. Its use is complementary to other flavor ingredients, and it is often combined with other aromatic compounds to create balanced notes and complexity. Sensory scientists and flavor houses develop tailored solutions based on market needs, consumer preferences, and regulatory constraints in different regions. The objective is to achieve consistent, desirable flavor profiles that align with consumer expectations for specific product categories. Because of its strong odor and flavor potency, food technologists must calibrate the amount used carefully. Small variations can result in noticeable changes in aroma. Modern flavor design often involves iterative sensory evaluation and analytical measurement to ensure the final product delivers the intended taste experience while maintaining safety and compliance.
Adi Example Calculation
To illustrate how Acceptable Daily Intake (ADI) concepts might be applied, consider a hypothetical body weight of 70 kilograms (approximately the average adult). If a flavoring agent had an ADI of 0.1 mg/kg body weight per day (this example number is hypothetical and not an assigned ADI for 1,3-butanedithiol), the calculation would involve multiplying 0.1 mg by 70 kg, resulting in an ADI of 7 mg per day. This means that, based on toxicological data and safety factors, an adult weighing 70 kg could theoretically consume up to 7 mg of that substance daily without expected health risk. For 1,3-butanedithiol, a specific numeric ADI has not been explicitly assigned by JECFA, which concluded ‘‘no safety concern at current levels of intake when used as a flavouring agent.’’ In this context, the ‘‘no safety concern’’ conclusion suggests that typical consumer exposure through food is well below any threshold that might raise safety questions. Nonetheless, understanding the ADI example helps clarify how regulators think about safety margins. In practice, the actual amount of a flavoring agent present in food is usually far lower than hypothetical ADI levels, as flavoring compounds are used in very small quantities to achieve sensory effects. For instance, a product formulated with a potent flavoring agent might contain only micrograms of that ingredient per serving. Even if a consumer consumed multiple servings per day, the total intake would remain far below a hypothetical ADI level. This example underscores why regulatory conclusions such as ‘‘no safety concern’’ are meaningful; they indicate that expected dietary exposure based on intended use conditions does not approach levels that would raise concern under typical consumption patterns.
Safety And Health Research
Safety assessments for food flavoring agents like 1,3-butanedithiol focus on understanding potential toxicological hazards, exposure levels, and the difference between hazard and actual consumer risk. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) review concluded that there is no safety concern at current levels of intake for 1,3-butanedithiol when used as a flavoring agent, indicating that available toxicological data supported its safety under typical use conditions. JECFA evaluations typically consider data on metabolism, acute and chronic toxicity, genotoxicity, and other endpoints relevant to consumer safety, and weigh these against expected exposure based on use levels in food. (世卫组织应用程序) Toxicological investigations for flavoring substances often involve studies in cell culture and animal models that examine potential effects on organ systems at various dosages. These studies help identify any possible adverse outcomes at doses significantly above those encountered by consumers in food. Flavoring agents with low toxicity and lack of evidence for genotoxicity or carcinogenicity at realistic exposure levels are generally considered acceptable for use when formulated according to good manufacturing practice. In the case of 1,3-butanedithiol, the ‘‘no safety concern’’ conclusion implies that the available data did not raise concerns in these key areas at anticipated dietary exposure. Researchers also consider the compound’s chemical reactivity because organosulfur compounds can interact with biological molecules. Metabolic pathways for sulfur-containing compounds vary widely, and while some metabolites can be biologically active, the overall safety conclusion reflects comprehensive analysis by expert panels. Specific data on human metabolism of 1,3-butanedithiol are limited, so conclusions rely on animal studies and chemical structure-based predictions to infer potential biological behavior. Human health research related to flavoring agents does not typically involve direct clinical trials due to ethical considerations and low exposure levels. Instead, safety evaluations integrate a range of data sources, including traditional toxicology tests, structure-activity relationships, and exposure assessments. The goal is to establish that typical dietary intake does not pose measurable health risks. Ongoing research and periodic re-evaluation by scientific committees ensure that safety assessments reflect current knowledge and methods.
Regulatory Status Worldwide
Globally, the regulatory status of 1,3-butanedithiol reflects its evaluation as a flavoring agent by scientific bodies that assess food additive safety. One key international evaluation is its entry in the Joint FAO/WHO Expert Committee on Food Additives (JECFA) database, where it is identified by JECFA Number 538 and described as having "no safety concern at current levels of intake when used as a flavouring agent." This conclusion is based on assessments of available toxicological data and typical exposure under intended uses in food products, as described in the WHO JECFA chemical summary. JECFA evaluations do not set a numeric acceptable daily intake (ADI) value unless explicitly indicated, but stating no safety concern reflects a conclusion that typical use does not pose a health risk at expected exposure levels under good manufacturing practice. (世卫组织应用程序) In the United States, flavoring substances are typically regulated through a combination of federal Food and Drug Administration (FDA) oversight and industry-established evaluations. The Flavor and Extract Manufacturers Association (FEMA) evaluates flavor ingredients for Generally Recognized as Safe (GRAS) status based on scientific evidence and expert review. 1,3-Butanedithiol is listed in the FEMA Flavor Library with an assigned FEMA number (3529), indicating that the FEMA Expert Panel has evaluated the substance for safety under intended use conditions as a flavoring agent. Such FEMA GRAS status is recognized in the food industry and submissions to the FDA’s Substances Added to Food inventory (formerly EAFUS) may include these flavoring agents, though inclusion does not necessarily confirm explicit FDA approval under specific CFR sections. (FEMA) In other regions, local regulatory frameworks evaluate flavoring substances through national or regional food safety agencies. For example, in the European Union, flavoring substances are overseen under EU flavoring regulations, and individual compounds are evaluated for safety and permitted use levels. While specific EU authorization details for 1,3-butanedithiol were not found in the evidence at hand, flavoring substances evaluated by JECFA and FEMA are often incorporated into national inventories with use conditions aligned to good manufacturing practice. Different regulatory systems may employ distinct classification approaches, but international scientific evaluations such as those by JECFA often inform local regulatory decisions.
Taste And Functional Properties
1,3-Butanedithiol is notable for its distinctive sensory qualities, particularly its strong alliaceous, sulfurous, garlic-like, and meaty aroma attributes. Organosulfur compounds such as this have low odor thresholds, meaning very small amounts can produce significant sensory effects. These characteristics make 1,3-butanedithiol a powerful tool for flavor formulators seeking to deliver robust savory notes in food applications. The sensory impact is often described as garlic or onion-like with additional roasted or meaty nuances, which can enhance the perception of depth and complexity in savory products. The functional properties of 1,3-butanedithiol extend beyond mere aroma. Its behavior in different food matrices depends on factors such as solubility and volatility. Thiol compounds typically exhibit limited solubility in water but better compatibility with fats and oil phases. As a result, they integrate well in food systems with significant lipid content, where they can contribute to overall flavor intensity without being readily lost to evaporation. In aqueous systems, careful formulation is required to ensure consistent dispersion and stability. Heat and pH can influence the stability and sensory expression of flavor compounds. While many flavoring agents may degrade under high temperatures or acidic conditions, 1,3-butanedithiol’s contribution to aroma is predominantly determined by its volatility and interaction with other volatile components during processing and consumption. Understanding how processing conditions affect its sensory output allows food scientists to optimize formulations for products that undergo cooking, pasteurization, or other thermal treatments. Because sulfur-containing compounds can interact with other ingredients, formulators must also consider potential synergistic or masking effects. Combining 1,3-butanedithiol with other flavor molecules can achieve more nuanced sensory experiences, enhancing specific notes while balancing undesirable off-notes. Sensory panels and analytical techniques help guide such decisions, ensuring that the final product delivers consistent flavor quality. While the compound’s sensory properties are well-utilized in savory contexts, its strong odor means precise formulation and application are crucial to avoid overpowering the overall flavor balance.
Acceptable Daily Intake Explained
The concept of an Acceptable Daily Intake (ADI) is central to how food safety authorities evaluate chemicals added to food, including flavoring agents like 1,3-butanedithiol. An ADI represents the amount of a substance that can be consumed every day over a lifetime without appreciable health risk, based on extensive toxicological data. ADIs are typically expressed in milligrams of the substance per kilogram of body weight per day. The ADI accounts for uncertainty by applying safety factors to the dose levels tested in animal studies, meaning the acceptable intake for humans is set well below levels that caused no observed adverse effects in experimental settings. For some food additives, regulatory bodies such as JECFA or EFSA establish numerical ADI values where sufficient data exist. An ADI value might be based on a No Observed Adverse Effect Level (NOAEL) identified in animal studies, with safety factors applied to ensure protection across diverse human populations. However, not all flavoring agents receive a numerical ADI. In the evaluation of 1,3-butanedithiol by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the conclusion was that there is no safety concern at current levels of intake when used as a flavoring agent, but a specific numeric ADI was not explicitly assigned. This reflects a regulatory judgment that typical consumption through food use does not pose measurable risk under good manufacturing practice. It is important to understand that an ADI is not a recommended target for daily consumption; rather, it is a safety benchmark used by regulators and food manufacturers to ensure that exposure stays within safe limits. Typical dietary exposure to flavoring agents is often orders of magnitude below any level that might raise concern, especially given that flavoring compounds are used in small quantities to achieve sensory effects. In practical terms, product developers and food scientists work within these safety frameworks by designing formulations that use the minimum effective amount of a flavoring agent, consistent with sensory goals and regulatory guidelines. For consumers, the presence of a flavoring agent assessed with ‘‘no safety concern’’ in expert evaluations means that the compound has undergone scientific scrutiny and is considered safe for use within the conditions defined by regulatory assessments.
Comparison With Similar Additives
Flavoring agents that provide savory, sulfurous, or alliaceous sensory qualities are a specialized subset of compounds used in the food industry. 1,3-Butanedithiol can be compared with other sulfur-containing flavor compounds such as diallyl disulfide and methional. Diallyl disulfide is another organosulfur compound contributing to garlic and onion-like flavors and is found naturally in garlic. While both 1,3-butanedithiol and diallyl disulfide contribute similar savory characteristics, their sensory thresholds and specific aromatic nuances differ, leading flavorists to select one compound over another based on desired flavor intensity and profile. Both compounds are used in very low concentrations due to their potent sensory impact. Methional, on the other hand, is a sulfur-containing aldehyde known for its cooked-potato and savory notes. Unlike dithiols, which are thiol-based sulfur compounds, methional’s aldehyde functional group contributes a different set of sensory properties. Methional can enhance the perception of warmth and depth in savory foods, while thiol compounds like 1,3-butanedithiol tend to deliver sharper alliaceous characteristics. In complex flavor formulations, combining compounds with complementary sensory contributions allows food scientists to build layered flavor experiences. Another related compound is 2-furfurylthiol, which is known for roasted coffee and savory notes. While chemically distinct from 1,3-butanedithiol, both compounds illustrate the diversity of sulfur-containing flavor molecules and their roles in creating distinct sensory impressions. The choice between these ingredients depends on the specific flavor profile desired, processing conditions, and interactions with other components in the food matrix. Comparisons among flavoring agents also take regulatory status into account. Each compound’s safety evaluation, use levels, and regulatory acceptance vary by region. For 1,3-butanedithiol, its inclusion in international expert evaluations with a ‘‘no safety concern’’ conclusion supports its continued use under relevant regulatory frameworks. Understanding the sensory and regulatory differences among similar additives helps flavorists optimize formulations while ensuring safety and compliance.
Common Food Applications Narrative
1,3-Butanedithiol is incorporated into a range of savory food applications where its savory, garlic-like, and meaty aroma enhances overall flavor perception. In culinary contexts where strong, characterful notes are desired, flavorists may include 1,3-butanedithiol as part of a complex flavor blend to contribute depth and nuance. Because of its powerful sensory attributes, it is typically used at very low concentrations tailored to specific product needs. In meat analog products, for example, creating a convincing savory profile often requires multiple volatile compounds that collectively mimic the aroma of cooked or roasted meats. 1,3-Butanedithiol’s contribution to alliaceous notes, reminiscent of garlic and cooked onions, helps anchor the flavor experience in familiar sensory territory for consumers. It works alongside other flavoring agents to generate a balanced and appetizing profile. Similar logic applies to soup bases and bouillon seasonings, where complex aroma profiles can elevate consumer perception of richness and depth. Snack foods and savory snacks also benefit from the inclusion of potent flavoring agents like 1,3-butanedithiol. In this category, manufacturers aim to deliver intense flavor experiences that stand out in competitive markets. The compound’s ability to contribute specific sulfurous and meaty notes complements other ingredients such as roasted nuts, spices, and umami-rich components. Carefully calibrated, it enhances overall flavor without overwhelming product identity. In sauces, gravies, and condiments, the compound’s sensory impact helps reinforce primary flavor themes. For example, in a garlic-infused sauce, the targeted use of 1,3-butanedithiol can amplify the product’s garlic character, making the sensory experience more vivid. In barbecue sauces or seasoned marinades, the combination of smoky, savory, and sulfurous notes contributes to perceived complexity. The formulation process involves expert sensory evaluation and analytical measurement to maintain consistency across production batches. While 1,3-butanedithiol’s primary applications are in savory products, it may also be included in specialty flavor blends developed for niche markets, such as gourmet seasonings or culinary enhancers designed for professional kitchens. In each case, the objective is to augment or refine specific sensory attributes that resonate with consumer preferences. The selection and optimization of such ingredients are guided by sensory science, understanding of flavor chemistry, and regulatory compliance in respective markets.
Safety & Regulations
FDA
- Notes: FDA has not listed an explicit CFR section for approval; FEMA GRAS status exists but does not itself constitute an FDA regulation.
EFSA
- Notes: No specific EFSA numeric authorization or E number was found.
JECFA
- Notes: JECFA concluded no safety concern at current intakes but did not explicitly assign a numeric ADI.
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