BUTYL ISOVALERATE

CAS: 109-19-3 FLAVORING AGENT OR ADJUVANT

Butyl isovalerate is a fruity ester used as a flavoring agent with regulatory listing under synthetic flavoring substances in the U.S. and evaluated by JECFA with no safety concern at current intake levels.

What It Is

Butyl isovalerate is an ester formed from isovaleric acid and butanol that is widely used in the flavor and fragrance industry for its fruity sensory profile. This compound, identified by CAS 109-19-3, is recognized in regulatory listings as a synthetic flavoring substance or adjuvant with specific allowance under U.S. food additive provisions. It is known by several synonyms including butyl isopentanoate and butanoic acid, 3-methyl-, butyl ester, which reflect its chemical structure and functional classification. Butyl isovalerate belongs to a class of organic esters that are commonly used to impart or enhance flavor in food and beverage formulations. Esters like butyl isovalerate are derived from the esterification of a carboxylic acid (in this case, isovaleric acid) with an alcohol (butanol), resulting in a compound with characteristic fragrance and taste properties attractive to product developers. As a flavoring agent, it is valued for its ability to contribute specific sensory notes associated with fruity character. This additive has been the subject of safety evaluations by international bodies such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA), which has concluded that at customary levels of intake in food, there is no safety concern when used as a flavoring agent. The role of this compound in food is not nutritive but strictly functional, enhancing sensory appeal in a controlled manner under good manufacturing practices. Regulators permit its use within defined frameworks of safe use and quality control.

How It Is Made

Butyl isovalerate is produced through an esterification reaction, a chemical process where isovaleric acid reacts with butanol in the presence of an acid catalyst. This reaction forms the ester linkage that defines butyl isovalerate, alongside water as a byproduct. Industrial production typically involves controlled reaction conditions that optimize yield and purity while minimizing unwanted byproducts. After the reaction is complete, the mixture may be refined through distillation and purification techniques to isolate the target ester at high purity suitable for flavor applications. In a manufacturing context, producers of flavor ingredients will adhere to quality standards that ensure food-grade quality, including meeting specifications set by regulatory and standard-setting bodies. For example, JECFA specifications outline identity and purity requirements for flavoring substances, which manufacturers use to benchmark their products. Following synthesis, the compound is characterized by analytical methods like gas chromatography and mass spectrometry to confirm composition and ensure it meets quality criteria. Good manufacturing practices (GMP) apply to the production of butyl isovalerate intended for use in food. These practices encompass aspects of raw material selection, reaction control, and post-synthesis handling to prevent contamination and ensure safety. Manufacturers also provide documentation such as certificates of analysis to verify that batches conform to established limits for purity and comply with specifications relevant to food-safe uses.

Why It Is Used In Food

Butyl isovalerate is used in food principally because of its ability to contribute a desirable fruity aroma and flavor profile that enhances the sensory quality of various food products. Flavor chemists choose specific esters like this one to tailor the taste experience of consumers, whether it is to replicate natural fruit flavors or to add complexity to crafted flavor blends. Its use is particularly relevant in products where a sweet, apple-like, or pear-like scent and taste can improve the overall appeal. In formulating food products, flavoring agents like butyl isovalerate are incorporated in very low concentrations, often measured in parts per million, to achieve the intended effect without overwhelming other flavor components. The substance is compatible with many food processing systems and can be blended with other esters, alcohols, or aromatic compounds to achieve balanced profiles. Flavor application might include confectionery, beverages, baked goods, or dairy-based products where fruity notes are desirable. Regulatory frameworks for flavoring substances specify that such compounds must be used at levels consistent with good manufacturing practice. This implies using the minimum amount necessary to achieve the functional effect, neither compromising safety nor exceeding the bounds of permissible use. Butyl isovalerate's inclusion in approved flavoring lists underlines its functional utility when applied thoughtfully by product developers.

Adi Example Calculation

This illustrative example demonstrates how an ADI might be used if it were established, and is not a recommendation for individual consumption. Suppose an additive had an ADI of 0.5 mg per kilogram of body weight per day; for an adult weighing 70 kg, the calculation would be: 0.5 mg/kg/day x 70 kg = 35 mg per day total allowable intake at that body weight. In the case of butyl isovalerate, a specific numeric ADI was not assigned by JECFA because the committee concluded that current exposure levels from use as a flavoring agent do not pose a safety concern. Therefore, this example serves only to illustrate the general concept of how ADIs are interpreted. The important takeaway is that ADIs provide a comparison between typical exposure and levels considered safe by expert evaluation, offering regulators and industry a framework for managing safety margins.

Safety And Health Research

Safety evaluations of butyl isovalerate focus on determining whether typical levels of intake as a flavoring agent pose any concern for human health. JECFA’s expert assessment concluded that at current levels of intake, there is no safety concern when butyl isovalerate is used as a flavoring agent. This conclusion is based on toxicological data and exposure assessment available at the time of evaluation and reflects a professional judgment about the compound’s hazard in the context of normal use. Regulatory bodies examine data related to metabolism, acute and chronic toxicity, reproductive effects, and other endpoints when assessing food additives. Flavoring agents are evaluated not only for inherent toxicity but also for patterns of consumption across diverse diets. When a compound is permitted for use, its inclusion in regulatory lists is accompanied by conditions such as use within the minimum amount required to achieve the intended effect and adherence to good manufacturing practices. Beyond formal evaluations, scientific literature may include studies on the occurrence of esters like butyl isovalerate in natural sources and their sensory characteristics, but such studies do not equate to safety assessments. Regulatory frameworks tend to rely on comprehensive reviews by expert bodies or official monographs that document safety findings. For butyl isovalerate, the consensus among authorities with available evaluations remains that customary use does not raise safety issues within the context of flavor applications.

Regulatory Status Worldwide

In the United States, butyl isovalerate is listed under the Code of Federal Regulations in Section 21 CFR 172.515, which covers synthetic flavoring substances and adjuvants permitted for direct addition to food under specified conditions of use. This regulatory listing means the compound is acknowledged as allowable in food formulations when used in compliance with good manufacturing practices and within the bounds of its intended technical function. The CFR provision itself outlines a broader set of substances, but inclusion in this list indicates regulatory acceptance at the federal level. Internationally, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated butyl isovalerate as a flavoring agent and reported that there is no safety concern at current levels of intake when used for its intended purpose. This evaluation, conducted in a past session, provides a scientific basis for countries and regions to consider the substance's safety under customary use patterns. The JECFA evaluation reflects a comprehensive review of available toxicological and exposure data, concluding that typical dietary exposure levels do not raise safety concerns. In the European Union, butyl isovalerate appears in flavoring inventories consistent with Regulation (EC) No 1334/2008 on flavorings and certain food ingredients with flavoring properties. Such listings identify compounds allowed for use in flavorings and specify conditions under which they may be incorporated into food, reflecting a harmonized regulatory approach across member states. While specific numerical use levels are not always prescribed, the context of flavoring use adheres to general principles of safety and good manufacturing practice.

Taste And Functional Properties

Butyl isovalerate has sensory properties described as sweet, fruity, and reminiscent of apple, pear, or pineapple notes. These sensory attributes derive from its molecular structure, which interacts with olfactory receptors to elicit perceptions associated with fruit-like aromas. In taste applications, the compound contributes to the complexity of flavor profiles without dominating the overall character, making it useful in multi-component flavor blends. Functionally, esters such as butyl isovalerate display solubility in organic solvents, and they are typically more soluble in alcohol than in water, which influences how they are formulated into food products. Their volatility contributes to aroma perception, especially in products that release flavor compounds upon consumption or heating. However, like other volatile esters, they may be subject to loss during high-heat processing, which formulators must account for when designing recipes. In practical food systems, the concentration and matrix of ingredients will affect how the compound functions. Esters may interact with fats, emulsifiers, or other flavor compounds, potentially enhancing or muting perceptions. Sensory scientists often conduct threshold testing to determine the concentration at which a flavor note becomes perceptible in a given product. Butyl isovalerate's moderate aroma strength makes it a candidate for nuanced role in flavor design.

Acceptable Daily Intake Explained

An Acceptable Daily Intake (ADI) is a scientific estimate of the amount of a substance in food that can be ingested daily over a lifetime without appreciable health risk. It is typically expressed in terms of milligrams of the substance per kilogram of body weight. For many flavoring agents evaluated by expert committees, including butyl isovalerate, regulatory evaluations may conclude that no numerical ADI is necessary because available data indicate that typical intake levels do not pose a health concern. In the case of butyl isovalerate, JECFA’s evaluation concluded there is no safety concern at current intake levels when used as a flavoring agent, which means that the committee did not establish a specific numeric ADI. This type of conclusion often indicates that dietary exposure is sufficiently low relative to any thresholds of toxicological concern. Thus, while there is no specific ADI number to communicate, the principle remains that the compound should be used in accordance with good manufacturing practices, using the minimum amount needed to achieve its intended flavoring effect. Consumers do not need to calculate ADIs for specific products, but understanding that regulatory bodies assess both the hazard and expected exposure helps explain why certain additives are permitted. An ADI, when established, serves as a reference point for regulators and industry to manage safety margins, but it is not a target or recommended level of consumption.

Comparison With Similar Additives

Flavoring esters like ethyl butyrate, isoamyl acetate, and methyl anthranilate share functional similarities with butyl isovalerate in that they are used to impart specific fruit-related sensory notes in food products. Ethyl butyrate often provides pineapple or orange-like notes, isoamyl acetate is associated with banana aroma, and methyl anthranilate imparts grape-like characteristics. Compared to these compounds, butyl isovalerate contributes a broader fruity profile that may complement or enhance a blend targeting green apple or pear-like impressions. While all these esters serve similar purposes in flavor design, their effective use depends on their individual sensory thresholds and how they blend with other components. Some esters may demonstrate stronger aroma intensity at lower concentrations, influencing how formulators balance total flavor profiles. The choice among these additives is often guided by the specific notes desired in the final product and how they interact with other ingredients. Regulatory status may vary across jurisdictions, but esters used for flavoring generally fall under the umbrella of synthetic flavoring substances permitted when used in accordance with good manufacturing practices. Their safety evaluations consider expected intake and toxicological data, with many such esters, including butyl isovalerate, showing no safety concern at current intake levels. Nonetheless, product developers rely on regulatory lists and guidance to ensure compliance in different markets.

Common Food Applications Narrative

In everyday food applications, butyl isovalerate finds its way into a range of products where fruity notes contribute to consumer appeal. For example, in beverages, this ester may be incorporated into fruit-flavored soft drinks or mixed juice blends to enhance or mimic natural fruit characteristics. Its inclusion helps achieve consistent flavor experiences across batches in contrast to relying solely on natural extracts, which can vary. In confectionery and baked goods, butyl isovalerate can support fruit-like flavor profiles in candies, cakes, and pastries where bright and sweet aromas are desired. Flavor formulators mix it with complementary compounds to build layered sensory experiences that resonate with fruit-inspired categories. In dairy products such as flavored yogurts or ice creams, low levels of this ester can help accentuate strawberry or apple notes without overpowering the base dairy character. Snack products, including fruit-flavored chips or bars, also leverage esters like butyl isovalerate to round out flavor formulations, particularly when the product aims to evoke a natural fruit essence. Because esters are volatile, they contribute more to aroma than to taste per se, making them valuable in products where smell and first impression influence consumer perception. Across these applications, product developers balance ester levels with other flavoring components to ensure a harmonious profile that aligns with product goals and regulatory guidelines.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 172.515

EFSA

  • Notes: Specific EFSA numerical evaluations not found in available data

JECFA

  • Year: 1997

Sources

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