ACETAL

CAS: 105-57-7 FLAVOR ENHANCER, FLAVORING AGENT OR ADJUVANT

Acetal (CAS 105-57-7) is an organic flavouring enhancer and agent permitted under FDA regulation 21 CFR 172.515 for use in foods as a synthetic flavouring substance.

What It Is

Acetal is an organic chemical compound defined by the molecular structure 1,1-diethoxyethane with CAS number 105-57-7. It belongs to the class of acetal compounds, which are formed by the reaction of an aldehyde with alcohols under controlled conditions. In the context of food science, ACETAL functions as a flavor enhancer and flavouring agent or adjuvant that imparts characteristic sensory notes when used in foods and beverages. The compound can appear as a clear, colourless liquid with a mild, ethereal or fruity aroma and is used in minute quantities to enhance or modify the flavour profiles of various products. The synthesis of the compound involves combining ethanol with acetaldehyde under catalysts to form the acetal linkage, resulting in the diethoxyethane structure. This specific acetal is recognized in regulatory frameworks and flavouring inventories for its intended technical function in food systems. The definition of Acetal as a flavouring agent is grounded in its molecular properties that allow it to interact with sensory receptors in a manner that enhances perceived flavours. As a flavouring agent, it is not intended to contribute substantial nutritive value but to modify or intensify flavour profiles of food and beverage matrices. The CAS number 105-57-7 uniquely identifies this substance in chemical registries and regulatory lists. ACETAL is included in official food additive regulations under specific conditions of use, indicating that regulators have determined conditions where it can be used safely in food processing and formulation. The compound has a long history of evaluation in flavour science and food additive specifications, and is part of official inventories of flavouring substances used in food applications.

How It Is Made

The manufacturing of Acetal typically involves a chemical synthesis route where acetaldehyde is reacted with ethanol or another suitable alcohol in the presence of acid catalysts to yield the diethoxyacetal structure. This process emphasizes the formation of an acetal linkage, where two ethoxy groups are bonded to a central carbon originally derived from acetaldehyde. Industrially, the reaction can be carefully controlled for temperature, catalyst choice, and purification steps to ensure high yield and desired levels of purity suitable for food use. Purification often involves distillation and other separation techniques to remove residual reactants and by-products, ensuring compliance with food-grade specifications and quality standards. Technical specifications for food-grade acetals also include analyses of residual solvents, moisture content, and potential impurities. In practice, the production of Acetal for use in food applications is conducted under Good Manufacturing Practices (GMP) and quality control frameworks that align with regulatory expectations for flavouring agents. Manufacturers must ensure that raw materials and catalysts meet safety and quality criteria and that final product testing confirms identity, concentration, and absence of unwanted contaminants. Since acetal compounds can be sensitive to storage conditions, manufacturers also provide guidance on stability and handling to maintain the integrity of the product through distribution and use in food processing. The compound’s synthesis route underscores its organic chemistry basis, while the quality control measures reflect the need to meet food additive standards set by authorities.

Why It Is Used In Food

ACETAL is used in food formulations primarily for its ability to act as a flavour enhancer and flavouring agent or adjuvant that contributes or accentuates desirable sensory attributes. Food scientists and flavour technologists incorporate ACETAL into certain products to deliver or boost fruity, ethereal, or nuanced sensory cues that complement other ingredients in the formulation. Its inclusion in flavour blends or as part of complex aromatic profiles helps manufacturers achieve consistent taste experiences in beverages, confections, baked goods, and other food categories where nuanced flavour perception is critical. The rationale for using Acetal in foods stems from the interplay between food chemistry and sensory perception. Certain compounds at low concentrations can trigger specific olfactory receptors, enhancing the perception of other flavours or adding subtle notes that round out and balance overall taste profiles. ACETAL’s capacity to provide fruit or nut-like nuances makes it useful in flavor design, particularly in products where such nuances are desirable, such as distilled spirits or fruit-flavoured food items. In this context, it acts in concert with other flavouring agents and ingredients to achieve target sensory attributes, enriching consumer experience. Moreover, ACETAL is used because it can be handled and formulated efficiently in processed food systems. Its compatibility with typical food processing conditions, including blending, heating, and storage, is part of why flavour chemists select it when designing flavour compositions. The use of regulated flavouring agents like ACETAL allows food producers to create complex and appealing sensory profiles while maintaining compliance with food safety standards defined by regulatory bodies.

Adi Example Calculation

To illustrate how an ADI concept might be applied in a hypothetical scenario, consider a hypothetical adult with a body weight of 70 kg. If a flavouring agent had an ADI of X mg per kg of body weight per day (a hypothetical number for explanation only), the total allowable intake for that individual would be calculated by multiplying the body weight by the ADI: 70 kg times X mg per kg per day equals 70X mg per day as the allowable intake over a lifetime. This example is illustrative and not specific to ACETAL, because a numeric ADI value is not explicitly provided in available published evaluation summaries. However, it demonstrates how regulators and risk assessors interpret ADI values relative to body weight to contextualize exposure and safety assessments. Such calculations underscore the role of ADI as a conservative benchmark rather than a target for consumer intake.

Safety And Health Research

Scientific and regulatory evaluations of flavouring agents like ACETAL focus on hazard identification, exposure assessment, and safety characterization. Toxicological data considered in safety assessments include acute toxicity studies, metabolic fate, and evaluations of potential chronic effects. In historical assessments by expert bodies such as JECFA, the compound has been subjected to review for its toxicological profile and dietary exposure patterns associated with typical uses in foods. Available summaries from such evaluations indicate that ACETAL does not raise safety concerns at current levels of intake when used as a flavouring agent. However, detailed toxicological studies and numeric benchmarks for acceptable daily intake may not be explicitly published in accessible summary documents, and detailed archival references may reside in comprehensive monographs. Regulators also consider data on irritancy and other hazard endpoints relevant to food handling and processing. For example, material safety data and chemical property references note that ACETAL can be irritant to skin and eyes and is flammable, informing safe handling guidance in manufacturing environments. In the food context, safety assessments take into account low concentrations of use and expected exposure levels among consumers across diverse food categories. Expert panels weigh these factors alongside analytical data on flavouring concentrations in foods to contextualize potential risks. Despite evaluations that support safety in use, ongoing research and monitoring remain part of the regulatory framework to ensure that emerging data and exposure trends continue to align with safety expectations. These considerations emphasize that regulatory evaluations of flavouring agents integrate both toxicological evidence and estimated intake to ensure consumer protection.

Regulatory Status Worldwide

In the United States, ACETAL is specifically listed under 21 CFR 172.515 as a synthetic flavouring substance and adjuvant permitted for direct addition to food when used in accordance with good manufacturing practice, indicating that the compound is considered safe for its intended use under specified conditions. This regulation defines the conditions under which synthetic flavouring substances may be safely used in food products, emphasizing minimal necessary quantities and compliance with established principles of formulation and processing. The inclusion of ACETAL in this list reflects regulatory review and acceptance that it can be used safely when consistent with prescribed practices. (21 CFR 172.515)​. Internationally, ACETAL has been evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and assigned JECFA number 941, which denotes its recognition in the context of flavouring agents evaluated for safety. JECFA evaluations historically consider the compound’s identity, use levels, toxicological data, and dietary exposure estimates to determine whether its use raises safety concerns. In available summaries from JECFA evaluations, ACETAL is noted as having no safety concern at current levels of intake when used as a flavouring agent, although specific numeric acceptable daily intake values are not explicitly provided in d evaluation summaries. Regulatory frameworks outside the U.S. and JECFA, such as in the European Union, maintain lists and evaluation processes for flavouring substances, though explicit inclusion or conditions of use for ACETAL may vary and require review of EU flavouring inventories and assessments. Overall, the regulatory status of ACETAL reflects its acceptance as a flavouring agent under defined conditions in several jurisdictions, underpinned by scientific assessments and ongoing monitoring by food safety authorities.

Taste And Functional Properties

Acetal is characterized by a distinctive sensory profile that may be described by trained flavour professionals as having ethereal, fruity, or slightly nut-like notes when perceived at appropriate concentrations. These sensory impressions make it suited to applications where such flavour nuances are integral to the desired product character. The compound’s volatility also contributes to its functional behaviour in flavour perception; more volatile molecules often reach the olfactory receptors quickly upon consumption, enhancing the overall flavour experience. However, due to its potency and volatility, it is typically used at low concentrations to avoid overwhelming the product’s intended profile. From a functional properties perspective, Acetal is soluble in a range of solvents and carriers that food formulators commonly use for flavour delivery systems. Its solubility profile allows it to be incorporated into oil-based or ethanol-based flavour premixes effectively. The functional behaviour of ACETAL also includes its stability under typical food processing conditions. While it is reasonably stable, formulation scientists consider factors such as heat, pH, and interaction with other ingredients to optimize its performance without degradation. At low pH levels or under extreme processing conditions, some acetal compounds may hydrolyze or transform, and formulators account for such behaviour in product development. The sensory impact of Acetal is often evaluated through sensory panels and analytical chemistry techniques to calibrate its contribution relative to other flavour components. Its detection threshold and interaction with matrix components inform formulation decisions, ensuring that the flavour profile aligns with consumer expectations and product specifications. The compound’s sensory and functional traits make it a useful tool in the formulation of complex flavours that require nuanced enhancement rather than dominant characterisation.

Acceptable Daily Intake Explained

An Acceptable Daily Intake (ADI) is a regulatory concept used to describe the amount of a substance that can be consumed every day over a lifetime without appreciable health risk, based on available toxicological data and conservative safety factors. For many flavouring agents, including ACETAL, JECFA and other expert bodies review data to determine whether specific numeric ADI values are warranted based on available evidence. In the case of ACETAL, evaluation summaries indicate no safety concern at current levels of intake when used as a flavouring agent, but an explicit numeric ADI may not be published in accessible summary reports. As such, numeric ADI values are set as null with notes indicating regulatory evaluation outcomes rather than specific limits. It is important to understand that the presence or absence of a defined numeric ADI in regulatory evaluations does not imply a lack of safety assessment. Rather, expert committees consider dietary exposure estimates, toxicological endpoints, and margins of safety in context. When a substance is determined not to pose safety concerns at typical levels of intake, regulators may not assign a specific numeric ADI in public summaries. Instead, the use of the compound in food is guided by conditions of good manufacturing practice and regulatory listings, ensuring that exposure remains within ranges considered safe based on scientific assessment. The concept of ADI helps regulators and industry stakeholders interpret safety data in ways that protect public health while allowing the functional use of flavouring agents in food products.

Comparison With Similar Additives

ACETAL can be compared with other flavouring agents that serve similar functional roles in enhancing or modifying sensory attributes in foods. For example, ethyl acetate is another ester-type flavouring compound with fruity notes used in beverage and confection flavour design. Both Acetal and ethyl acetate contribute volatile fruity aromas, but they differ in their chemical structures, sensory nuances, and volatility profiles. Ethyl acetate has a more straightforward ester linkage and is perceived with stronger fruity and solvent-like notes at higher concentrations, whereas ACETAL’s diethoxy structure often yields subtler ethereal nuances. Another comparative example is ethyl butyrate, a flavouring ester known for its strong fruity impression reminiscent of pineapple or tropical fruit. While ACETAL imparts ethereal or nuanced fruity notes, ethyl butyrate’s sensory impact is more pronounced and often used where bold fruit notes are desired. These differences in sensory character inform formulation choices depending on the target flavour profile. All these flavouring agents are evaluated for safety and regulatory compliance within their respective jurisdictions, and their permitted use levels and conditions are defined based on scientific assessments that consider typical exposure and functional roles. Such comparisons help food technologists select appropriate compounds and balance flavour profiles in complex formulations.

Common Food Applications Narrative

Acetal finds application in a diverse range of food products where nuanced flavour enhancement is desired. In beverage applications such as distilled spirits, the compound’s fruity and ethereal notes can complement the inherent flavour profile of malt whiskies, sherries, and other aged spirits, contributing to consumer perceptions of complexity and depth. In such products, Acetal may be present as a naturally occurring component or added as part of a flavouring blend to achieve consistent sensory qualities across batches. Beyond spirits, Acetal’s flavour-enhancing properties are appreciated in formulated food products like fruit-flavoured beverages, confections, and bakery items. In fruit-flavoured drinks, it can accentuate perceived fruitiness or add subtle layers to a composite aroma profile. In confections such as sugar-based candies and gelled sweets, the compound helps round out flavour notes, contributing to a more appealing taste experience. Similarly, baked goods that incorporate fruit or nut flavour profiles may include ACETAL as part of flavour design strategies to achieve a balanced, multi-dimensional aromatic quality. Food manufacturers also explore its use in flavour blends that aim to mimic or enhance natural sensory characteristics, allowing for consistent flavour delivery in products where ingredient variability might otherwise impact taste. In these contexts, careful formulation ensures that ACETAL enhances rather than dominates the product’s flavour, aligning with both sensory goals and regulatory guidelines for food additives. Its inclusion in these applications reflects both the artistry and science of flavour creation within the food industry.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 172.515

EFSA

  • Notes: EFSA evaluation specific numeric values not identified

JECFA

  • Notes: JECFA evaluations indicate no safety concern at current intake levels without explicit numeric ADI

Sources

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