BUTYL BUTYRATE

CAS: 109-21-7 FLAVORING AGENT OR ADJUVANT

Butyl butyrate (CAS 109-21-7) is a fruity ester used as a food flavoring agent or adjuvant with a sweet, pineapple like aroma. It has recognition in flavor inventories and regulatory listings.

What It Is

Butyl butyrate is an organic ester compound defined by the chemical structure formed through the condensation of butyric acid and n-butanol. It is identified by the CAS number 109-21-7 and included in flavoring inventories such as the United States Food and Drug Administration's substances added to food list under 21 CFR 172.515 as a flavoring agent or adjuvant. It is known by multiple synonyms that reflect the same chemical structure, including butyl butanoate, butanoic acid butyl ester, and other systematic names used in chemical indexing. The compound is typically a clear, colorless liquid at room temperature with a characteristic sweet and fruity aroma reminiscent of pineapple and other fruits. Butyl butyrate belongs to a class of volatile esters that are commonly used in flavor formulations because of their sensory properties and compatibility with a range of food matrices. Flavoring agents like butyl butyrate are categorized based on their role in imparting or modifying sensory characteristics of food and beverage products without contributing nutritive value. They are intended to provide a specific flavor profile or to enhance other flavor components in a formulation. Butyl butyrate's inclusion in flavor libraries and its listing in regulatory flavor inventories reflect its established use and recognized technical function. Although esters like butyl butyrate occur naturally in many fruits and fermentation products, their commercial use in food systems typically involves carefully defined and controlled applications to achieve consistent sensory outcomes. In regulatory inventories and technical databases, butyl butyrate is referenced by its structural identifiers and functional class rather than by numeric daily intake recommendations. This is because flavoring agents are generally evaluated based on their safety at typical use levels rather than assigned numeric acceptable daily intake values. The presence of butyl butyrate in flavor inventories provides manufacturers and regulators with a framework for its authorized technical use and labeling considerations.

How It Is Made

Butyl butyrate is synthesized through well established chemical processes that involve esterification reactions. At a high level, the compound is formed by reacting butyric acid with n-butanol in the presence of an acid catalyst. This type of esterification results in the removal of water and the formation of an ester bond, yielding the characteristic butyl butyrate molecule. Industrial scale production of food grade flavor esters like butyl butyrate typically involves controlled reaction conditions, purification steps to remove unreacted starting materials, and quality assurance to meet defined purity criteria appropriate for use in food products. In practice, the esterification process can be carried out in batch or continuous reactors, and the selection of catalysts, temperatures, and process controls is informed by the need to achieve efficient conversion while minimizing by product formation. After synthesis, purification techniques such as phase separation, washing, neutralization of residual acids, and vacuum distillation are used to isolate butyl butyrate with a purity suitable for flavor applications. Food industry flavor manufacturers follow established good manufacturing practices that address contaminant control, traceability, and adherence to regulatory specifications for food ingredients. Quality specifications for food grade butyl butyrate include assessments of color, clarity, odor, and limits on impurities that could affect sensory or safety outcomes. Because butyl butyrate is volatile and contributes aromatic character, its handling and storage must also account for preservation of sensory integrity. The manufacturing environment is typically designed to limit exposure to contaminants while ensuring that the final product meets the functional needs of flavor formulators. Beyond chemical synthesis, butyl butyrate also occurs naturally in many fruits and fermentation products, where enzymatic processes in the plant or microbial metabolism generate the ester. However, natural occurrence does not substitute for controlled industrial production when consistency and volume requirements for food manufacturing are needed. Documentation of production methods in industry references and safety databases reflects the standard approaches used to produce high quality flavor esters.

Why It Is Used In Food

Butyl butyrate is used in the food industry primarily to provide or enhance fruity flavor profiles. Its sweet, pineapple like sensory character makes it desirable in formulations aiming to evoke tropical fruit notes or to complement other fruit derived flavors. Flavoring agents like butyl butyrate play a technical role in creating specific taste perceptions that would otherwise be difficult to achieve with natural ingredients alone or with other flavoring substances. In composite food systems, butyl butyrate can help achieve balance and complexity by contributing a targeted ester note that pairs well with other flavor components. It may be used in fruit flavored beverages, confectionery, dairy based desserts, and other applications where a sweet fruit aroma is desirable. The choice of a particular flavoring agent is guided by the overall profile of the product, processing conditions, stability considerations, and regulatory compliance for intended markets. Manufacturers consider functional properties such as volatility, solubility, and interaction with other ingredients when selecting flavoring esters. Butyl butyrate’s volatility contributes to aroma perception, which is important in products where olfactory cues influence consumer acceptance. As a technical additive, its use is not for nutritive contribution but strictly to achieve the sensory experience expected by consumers of flavored products. Flavor technologists also evaluate how flavoring agents behave under processing conditions such as heat, pH changes, and storage. Butyl butyrate’s stability is taken into account when formulating products that may undergo pasteurization or other thermal treatments. In many cases, flavor houses blend a suite of esters and other flavoring components to achieve complexity, and butyl butyrate may be one of several compounds contributing to the intended sensory effect. The controlled use of flavoring agents supports product consistency across production batches and helps manufacturers meet consumer expectations for taste and aroma.

Adi Example Calculation

An illustrative example helps explain how acceptable daily intake concepts apply in regulatory contexts, even for substances where a numeric ADI is not assigned. Suppose a hypothetical scenario in which a flavoring agent with a numeric ADI of X mg per kilogram of body weight per day is consumed. For an adult weighing 70 kilograms, the daily intake at the ADI level would be calculated by multiplying X mg by 70. This calculation yields an estimate of total allowable intake that regulators consider unlikely to cause harm over a lifetime of exposure. Although butyl butyrate’s evaluation did not result in a numeric ADI, the same logic applies to interpret safety evaluations: actual intake levels from flavored foods are typically orders of magnitude lower than thresholds of concern established by toxicological data and expert judgment. The purpose of presenting such a calculation is not to provide personal dietary guidance, but to illustrate how numeric ADIs are used in regulatory science to relate body weight and exposure. In practice, exposure estimates for flavoring agents are derived from consumption data, typical use levels in food products, and patterns of intake across populations. These exposure assessments are compared to safety thresholds to determine whether additional regulatory action or limitation is necessary. In the case of butyl butyrate, expert evaluation concluded that typical exposures fall well below levels of concern, and therefore a numeric ADI value was not assigned. It is essential to recognize that such illustrative calculations rely on numeric ADI values assigned by regulatory bodies, which are based on comprehensive evaluation of toxicological and exposure data. For substances without a numeric ADI, qualitative safety conclusions still reflect scientific assessment but are communicated differently. The general principle remains that regulators aim to ensure that intake from food does not result in appreciable health risk, using the best available evidence.

Safety And Health Research

Regulatory bodies and expert committees evaluate flavoring agents like butyl butyrate based on available toxicological and exposure data to determine whether their use at typical levels raises safety concerns. For butyl butyrate, evaluations by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) concluded that there is no safety concern at current levels of intake when used as a flavoring agent, reflecting an assessment of available data on metabolism, toxicity, and exposure. JECFA’s conclusion is informed by considerations of the compound’s metabolism, which yields simple metabolites that are common in normal human biochemical pathways, as well as typical use levels in flavored foods. Toxicological studies relevant to regulatory assessment often include data on acute toxicity, where high doses in test animals inform hazard characterization, as well as studies on longer term exposure where available. For many flavoring agents, data on chronic toxicity and reproductive endpoints are limited, and expert committees rely on panels of structurally related compounds and established thresholds of concern. In the case of butyl butyrate, its metabolic fate and historical use support a regulatory perspective that typical exposures from flavored food products do not present safety concerns when used within good manufacturing practice. Food safety research also examines the potential for irritation, sensitization, and other local effects that may be relevant to handlers and consumers. Although butyl butyrate has an aromatic profile that is beneficial for flavor, it can have irritant properties at high concentrations outside typical food use. Such information is incorporated into material safety data sheets and occupational health guidelines for industrial settings, distinct from considerations of dietary exposure. Regulators continue to monitor emerging data on flavoring agents, and safety assessments may be updated as new information becomes available. For food manufacturers, adherence to established regulatory listings and specifications ensures that flavoring agents are used in a manner consistent with current safety evaluations.

Regulatory Status Worldwide

Regulatory frameworks for flavoring agents like butyl butyrate vary by region, but many jurisdictions maintain inventories that define acceptable technical use. In the United States, butyl butyrate is included in the Food and Drug Administration’s inventory of substances added to food, formerly known as EAFUS, under Title 21 of the Code of Federal Regulations at section 172.515. This listing indicates that the compound is recognized for use as a flavoring agent or adjuvant in food products when used in accordance with good manufacturing practice. The CFR section provides the regulatory foundation for manufacturers to include butyl butyrate in flavor formulations intended for human consumption in the U.S. At the international level, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated butyl butyrate as part of its flavoring agents assessments. The World Health Organization’s JECFA database notes that butyl butyrate (identified under JECFA number 151 and FEMA number 2186) has been reviewed and that no safety concern was identified at current levels of intake when used as a flavoring agent. This type of evaluation provides scientific context that supports regulatory decisions and industry practice in diverse markets where JECFA assessments inform national standards. Within the European Union, flavoring agents are subject to specific regulatory frameworks that establish lists of authorized flavoring substances and use conditions. While butyl butyrate is commonly used in many EFSA jurisdictions within food flavoring applications, specific numeric approvals, E number assignments, or tolerances are determined through region specific evaluations, and for this compound an EFSA E number designation is not explicitly documented here. National and regional regulations outside the U.S. and EU also may include butyl butyrate within permitted flavoring substance lists, with conditions that reflect local food safety and labeling requirements. Overall, the regulatory status of butyl butyrate reflects its long history of use and evaluation in flavor applications. Listings in recognized inventories and expert evaluations contribute to a framework that allows food manufacturers to employ the compound in food products while meeting compliance obligations in the countries where their products are marketed.

Taste And Functional Properties

Butyl butyrate is noted for its sensory properties, specifically a sweet, fresh, and fruity aroma reminiscent of pineapple and other tropical fruits. The compound’s ester functional group contributes to its volatility and aromatic impact, making it a valuable component in flavor formulations where prominent fruity notes are desired. Sensory literature characterizes butyl butyrate as having a distinct fruit like odor that can be perceived even at low concentrations, which is typical of volatile esters used in the flavor industry. Functionally, butyl butyrate exhibits solubility characteristics that influence how it is incorporated into food systems. Like many esters, it is more soluble in organic solvents and lipid phases than in water, and formulators account for this when designing emulsions, beverages, or other products. The volatility of butyl butyrate can also affect how it persists through processing and storage, as some loss of aroma may occur if not adequately encapsulated or stabilized within the matrix. In terms of heat and pH stability, esters such as butyl butyrate can be sensitive to hydrolysis under extreme conditions. Flavor chemists select appropriate carriers and techniques to protect the compound during product manufacturing. For example, microencapsulation or use of flavor precursors may be employed to preserve the desirable sensory properties until consumption. Importantly, sensory perception of flavoring agents like butyl butyrate is influenced by the overall composition of the product. The presence of sugars, acids, and other aroma compounds interacts with the ester’s profile to create the final flavor experience. This interplay is a central consideration in flavor design, as the balance of components determines whether the target profile is successfully achieved. Butyl butyrate’s contribution is typically described in terms of its specific aroma characteristics rather than its nutritional or functional contribution to food structure.

Acceptable Daily Intake Explained

The concept of an acceptable daily intake (ADI) is used by regulators to describe an estimate of the amount of a substance that can be consumed daily over a lifetime without appreciable health risk, based on available data and safety factors. For many flavoring agents, including butyl butyrate, expert committees such as the Joint FAO/WHO Expert Committee on Food Additives evaluate toxicological data and typical exposure levels. In the case of butyl butyrate, the committee’s evaluation concluded that there was no safety concern at current levels of intake when used as a flavoring agent. This conclusion is not expressed as a numeric ADI, but rather reflects an assessment that typical dietary exposures do not approach levels that would raise safety issues. It is important to distinguish between numeric ADI values and qualitative safety evaluations. A numeric ADI, often expressed in milligrams per kilogram of body weight per day, provides a specific intake threshold informed by toxicological studies and safety factors. When regulators conclude that no safety concern exists at current intake levels without assigning a numeric ADI, it indicates that exposure from expected use in food products is far below levels of concern based on available data. This approach is common for many flavoring substances where metabolic pathways and historical use support a low likelihood of adverse effects at typical exposure levels. For food manufacturers and consumers, the regulatory framework that includes safety evaluations and inventories of permitted flavoring agents serves as the basis for confidence in the technical use of compounds like butyl butyrate. The absence of a numeric ADI should not be interpreted as an absence of safety evaluation, but rather reflects the nature of the evidence and expert judgment applied to dietary exposure scenarios. As scientific understanding advances and new data become available, regulatory evaluations are periodically revisited to ensure continued alignment with current knowledge.

Comparison With Similar Additives

Butyl butyrate shares functional similarity with other esters used as flavoring agents in the food industry. For example, ethyl butyrate is another fruity ester that contributes pineapple and orange like notes in flavor formulations, offering a slightly different aroma profile that can complement or contrast with butyl butyrate’s character. Both compounds belong to the class of aliphatic esters known for their volatile aromatic properties but differ in their alcohol moiety, which influences sensory perception and solubility behavior. Ethyl butyrate often provides a sharper fruit note, whereas butyl butyrate’s profile may be perceived as smoother or more rounded. Isoamyl acetate is another ester used in flavor applications, particularly to evoke banana like notes. While structurally distinct from butyl butyrate, isoamyl acetate shares the functional characteristic of providing a recognizable fruity aroma at low concentrations. The choice between these esters depends on the target flavor profile and the balance of sensory components needed in a formulation. In some cases, flavorists blend multiple esters to achieve complexity, leveraging the complementary properties of each compound. Beyond esters, lactones such as gamma undecalactone contribute peach and creamy fruit notes in certain applications. Lactones differ chemically from simple esters like butyl butyrate, but functionally they similarly affect aroma perception by contributing distinct sensory cues. The use of lactones and esters together requires careful formulation to avoid overpowering specific notes or creating unintended interactions. The common thread among these flavoring agents is their role in shaping sensory experiences through volatile aromatic properties. Each compound’s unique chemical structure influences its aroma character, volatility, and functional behavior in foods and beverages. Butyl butyrate’s sweet, pineapple like profile positions it among a suite of esters that flavorists choose based on the desired sensory outcome, processing conditions, and regulatory allowances in targeted markets.

Common Food Applications Narrative

Butyl butyrate is incorporated into a variety of flavored food and beverage products because of its distinctive fruity aroma and its capacity to enhance flavor profiles in combination with other ingredients. In fruit flavored beverages, both carbonated and non carbonated, this compound contributes to the perception of tropical fruit notes that consumers associate with pineapple, banana, and similar fruits. Combined with other esters and flavoring agents, it helps create a layered sensory experience that resonates with the intended fruit theme. In confectionery products such as hard candies, gummies, and chewable sweets, butyl butyrate supports the overall fruit flavor impact by adding dimension to the aromatic profile. These applications often require precise balancing of multiple flavoring substances to achieve the desired intensity without overwhelming the palate. Dairy based desserts, including flavored yogurts, ice creams, and frozen novelties, may also incorporate butyl butyrate when a fruit character is part of the formulation. Because these products often undergo thermal processing steps, formulators account for the compound’s stability and adjust concentrations accordingly to ensure that the final product maintains the targeted sensory attributes. Beyond traditional fruit flavored products, butyl butyrate finds use in bakery items such as fruit filled pastries, where it complements natural fruit ingredients and enhances the perception of ripeness and sweetness. The compound’s role extends to flavoring of syrups, gelatins, and drink mixes, where its volatile profile contributes to aroma release during preparation or consumption. The ability to evoke a specific fruit character makes butyl butyrate useful in crafting consistent and recognizable flavor signatures across product lines. Because consumer expectations for flavor profiles are shaped by cultural and sensory norms, food scientists select compounds like butyl butyrate with careful consideration of how they interact within complex formulations. In practice, the application of butyl butyrate in food products is governed by regulatory allowances and specifications that determine acceptable use levels. Flavor houses provide technical guidance on usage, and manufacturers implement these recommendations within the context of their formulations. Through this technical collaboration, products such as fruit flavored drinks, candies, dairy desserts, and baked goods consistently achieve the sensory qualities that appeal to consumers.

Safety & Regulations

FDA

  • Notes: Included in the FDA substances added to food inventory with a specified CFR section, but explicit numeric approval status cannot be independently confirmed without the specific listing text.
  • Regulation: 21 CFR 172.515

EFSA

  • Notes: No specific numeric ADI or E number assignment is clearly documented on EFSA for this compound.

JECFA

  • Year: 1997
  • Notes: JECFA evaluation concluded no safety concern at current intake levels when used as a flavoring agent; numeric ADI not assigned.

Sources

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