CYCLOHEXANONE

CAS: 108-94-1 FLAVORING AGENT OR ADJUVANT

Cyclohexanone is a colorless cyclic ketone used in food flavoring contexts that has been evaluated by international bodies for use as a flavouring agent under specific conditions of use.

What It Is

Cyclohexanone is a chemically defined cyclic ketone (CAS 108-94-1) that functions as a flavoring agent or adjuvant in food applications. It belongs to a class of small organic ketones characterized by a six‑membered ring containing a carbonyl functional group. Other names listed for cyclohexanone include ketohexamethylene, pimelic ketone, and cyclohexyl ketone, reflecting historical or structural synonyms used in chemical databases and industrial contexts. The designation of flavoring agent or adjuvant refers to its use to impart or enhance flavor characteristics rather than to provide nutritional value. The technical function of cyclohexanone in food systems is primarily related to sensory modification at low concentrations rather than nutritional enrichment or preservation. In international safety evaluations, cyclohexanone has been reviewed in the context of flavouring substances used in foods, particularly those chemically defined and of low exposure. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated cyclohexanone and concluded that there is “no safety concern at current levels of intake when used as a flavouring agent.” This type of evaluation reflects a risk assessment based on likely human exposure, metabolism, and toxicological data. The flavoring designation differentiates it from other food additive classes such as preservatives, colorants, or direct nutritional additives. Flavoring agents in general are regulated based on both their identity and the conditions under which they are used in food products, and cyclohexanone falls into this category of chemically defined flavouring components rather than bulk food ingredients. Other identifiers and classification frameworks, such as FEMA (Flavor and Extract Manufacturers Association) and JECFA numbering systems, assign unique registry numbers to cyclohexanone to support international communication and regulatory tracking. Cyclohexanone’s CAS number (108‑94‑1) is a widely accepted identifier in chemical inventories and regulatory documents across jurisdictions, although specific authorizations and limitations may vary depending on local food additive regulations. Its listing in codified inventories and evaluations facilitates understanding of its technical role and regulatory context in food flavour applications.

How It Is Made

Cyclohexanone is produced industrially through organic synthesis pathways typical for ketones. Commercial methods often involve the catalytic oxidation of cyclohexane or the hydrogenation and subsequent dehydrogenation of phenol intermediates. In the oxidation route, cyclohexane is exposed to oxidizing conditions in the presence of catalysts that facilitate conversion to cyclohexanone and by‑products; the resulting crude mixture is refined and purified to reach specification grades suitable for industrial use. Purification steps can include distillation and fractional separation to achieve the desired purity for flavoring agent applications. The overall chemistry centers on carbon‑oxygen functional group transformations that are standard in large‑scale organic chemical manufacturing. From a manufacturing standpoint, cyclohexanone must meet defined quality and purity criteria to be considered for use in flavoring or food applications. Food‑grade materials are typically produced under good manufacturing practices with quality control measures that include specification of residual solvents, impurities, and physical properties such as boiling point and odor profile. The food‑grade raw material is often tested and certified against specification monographs or analytical standards to ensure it is consistent with regulatory expectations for a flavoring ingredient. The synthesis and purification processes for cyclohexanone are rooted in core organic chemistry transformations widely used for ketone production. Depending on the precursor and intermediate chemicals used, pathways may differ slightly between manufacturers, but the overarching goal is to reliably produce cyclohexanone at high purity with minimal contaminants. Because cyclohexanone also has industrial uses outside food, the production stream may be segmented for different end‑use markets with appropriate quality controls tailored to each application. In food flavoring contexts, this means additional analytical verification and traceability to ensure that the product meets food additive specifications and is free from harmful processing residues or contaminants.

Why It Is Used In Food

Cyclohexanone is used in food primarily as a flavoring agent or adjuvant, where its presence can contribute to specific taste profiles or enhance the perception of certain flavors. In flavor chemistry, low‑level organic ketones like cyclohexanone are selected for their characteristic odor and taste attributes; these compounds can impart subtle notes that complement or balance other ingredients in a formula. The classification as a flavoring agent emphasizes its sensory role rather than nutritional or preservative functions. In the context of food formulation and flavor design, flavoring agents like cyclohexanone are used in very low concentrations because human taste and olfactory receptors are extremely sensitive to many volatile organic compounds. The goal is to achieve the desired sensory outcome without overwhelming the product’s intrinsic taste. Cyclohexanone’s particular structure and olfactory properties may be favored in specialized flavor systems, especially where a cooling, minty, or aromatic note is desired, consistent with the technical assessments in flavor libraries and flavor evaluation databases. Flavoring agents are often combined with carrier systems or other flavor chemicals to build complex sensory profiles tailored to specific foods or beverages. The choice of a specific flavoring compound depends on the desired aroma profile, volatility, solubility, and stability in the finished food matrix. Although cyclohexanone is not one of the most common broad‑spectrum flavor ingredients, it has been evaluated and assigned a registry number in flavor evaluation systems, indicating that it has a defined role within a larger portfolio of flavoring substances. This type of use highlights how formulation chemists leverage individual chemicals to achieve precise flavor outcomes in diverse food products.

Adi Example Calculation

Because cyclohexanone’s evaluation did not result in a numerical ADI, an illustrative calculation is provided to explain how ADIs are used in risk assessment. For example, if a hypothetical flavoring compound had an established ADI of 1 mg/kg bw/day, a person weighing 70 kg would have an illustrative safe exposure threshold of 70 mg per day (70 kg x 1 mg/kg bw/day). This type of calculation helps contextualize exposure figures, but in the case of cyclohexanone, there is no specific numeric ADI established by JECFA. Such illustrative examples are useful for understanding how regulators compare estimated intake levels from foods to established safety benchmarks. The ADI concept supports decisions about whether additional data or restrictions are necessary. In the context of flavoring agents, conservative safety factors and low exposure estimates typically result in minimal consumer risk when used as intended.

Safety And Health Research

Safety assessments for food flavoring substances focus on evaluating hazard potential relative to likely human exposure. International expert panels, such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA), review toxicological data, metabolic pathways, and exposure estimates to determine if a substance presents safety concerns under typical use conditions. For cyclohexanone, JECFA’s evaluation concluded that its use as a flavouring agent did not raise safety concerns at expected intake levels. This conclusion is based on the compound’s chemical properties, available toxicological studies, and conservative exposure assumptions that account for typical dietary use. Flavoring substances are generally used at low concentrations compared with other food additives, which often results in low overall dietary exposure. As a consequence, risk assessments prioritize understanding potential systemic toxicity, genotoxicity, and other endpoints relevant to chronic intake. Regulatory evaluations for flavoring agents integrate both the available scientific data and exposure context to determine if there is a reasonable certainty of no harm at intended use levels. In addition to formal regulatory evaluations, scientific studies may explore the physicochemical behavior and toxicological profiles of compounds like cyclohexanone under laboratory conditions to support safety assessments. These investigations provide background data that inform expert panels and help establish analytical specifications and purity criteria. While cyclohexanone’s toxicological profile is primarily characterized through such evaluations, regulatory bodies adopt precautionary approaches that consider worst‑case exposure scenarios and apply safety factors to account for uncertainties.

Regulatory Status Worldwide

The regulatory status of cyclohexanone varies by jurisdiction and the context of its intended use. In the United States, cyclohexanone appears in the Code of Federal Regulations in the context of indirect food additives. Specifically, 21 CFR 177.2250 permits the use of cyclohexanone as a solvent in the production of microporous polymeric filters used in food processing, with a maximum limit of 0.35 percent by weight in the finished filter article. This regulatory citation reflects a specific functional use in food contact materials rather than authorization as a direct food additive or flavoring substance. The regulation outlines conditions for its safe use in components that may contact food during processing operations. The inclusion of cyclohexanone in this section demonstrates that regulatory frameworks recognize its technical roles in food‑related manufacturing operations, with defined limits to ensure safety in contact applications. Internationally, cyclohexanone has been evaluated by bodies such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA), which reviewed it as a flavoring agent. JECFA’s evaluation concluded that “there is no safety concern at current levels of intake when used as a flavouring agent,” indicating that, based on available data and typical exposure scenarios, cyclohexanone’s use in flavor applications is not associated with safety concerns at customary use levels. This type of evaluation supports its inclusion in flavoring inventories and informs international regulatory considerations. In the European Union, flavoring substances are subject to evaluation under food flavor regulatory frameworks, and specific lists of authorized flavoring agents are maintained. While general regulatory guidance for flavorings exists, individual substance authorizations and use conditions require EFSA review and inclusion in the EU flavoring inventory. At this time, specific EFSA evaluations for cyclohexanone as a flavoring agent have not been identified, and therefore formal authorization details under EU food additive regulations may vary. Overall, the regulatory landscape reflects tailored assessments across regions, emphasizing safety at intended use levels and adherence to prescribed conditions of application.

Taste And Functional Properties

From an organoleptic perspective, cyclohexanone is described in flavor evaluation contexts as having sensory notes that may be perceived as cool, minty, or aromatic, which can be useful in designing certain flavor profiles. Its functional behavior in food systems is governed by its volatility, solubility, and interaction with other flavor components. Volatile compounds with specific odor thresholds play critical roles in the overall perception of flavor, and cyclohexanone’s physical chemistry supports its use at low levels in complex mixtures. Cyclohexanone is a relatively small molecule with moderate volatility, which means it can contribute to the top notes of a flavor profile without persisting excessively in the background. Its solubility characteristics in aqueous and lipid systems influence how it partitions between phases in beverages, baked goods, and other formulations, affecting how consumers perceive its contribution to aroma and taste over time. The balance of volatility and stability is a key consideration when selecting flavoring agents for specific applications. In addition to sensory attributes, cyclohexanone’s functional properties include a predictable chemical behavior under typical processing conditions. Flavoring compounds used in food must remain stable during mixing, storage, and moderate heat exposure; ingredients that degrade or react undesirably can distort the flavor profile or introduce off‑notes. Cyclohexanone’s chemical structure confers a level of stability appropriate for its intended flavoring role, provided that formulation and processing parameters are managed to avoid unintended reactions or loss of desired sensory characteristics.

Acceptable Daily Intake Explained

An Acceptable Daily Intake (ADI) is a concept used in food safety risk assessment to describe the amount of a substance that can be consumed daily over a lifetime without appreciable health risk. ADIs are typically expressed in terms of milligrams of substance per kilogram of body weight per day (mg/kg bw/day) and are established based on toxicological data and safety factors. In the case of cyclohexanone, JECFA’s evaluation indicated that there is no safety concern at current levels of intake when used as a flavouring agent, and a specific numerical ADI was not assigned. The absence of a formal numeric ADI in this context reflects an assessment that typical exposures to cyclohexanone from flavoring use are very low and do not warrant a quantitative limit. Because flavoring agents are consumed in very small amounts, regulators often consider whether a formal ADI is necessary when conservative assessments show no safety concern. ADI values, when assigned, help regulators and manufacturers ensure that exposure to a substance remains within safe boundaries. They are derived from no‑observed‑adverse‑effect levels (NOAELs) identified in toxicological studies, adjusted by uncertainty factors to account for variability between animals and humans and other considerations. For substances like cyclohexanone where typical exposure is minimal and evaluations do not indicate health concerns, a formal ADI may not be explicitly defined, but regulatory assessments still consider safety through qualitative conclusions about intake levels.

Comparison With Similar Additives

Cyclohexanone can be compared with other chemically defined flavoring agents used to impart specific sensory attributes. For example, compounds such as vanillin and ethyl butyrate are used to convey vanilla and fruity notes, respectively, and are evaluated and authorized for use based on their flavor profiles and safety assessments. Flavoring agents differ in their molecular structures, olfactory thresholds, and functional roles in formulations. Cyclohexanone’s role is often more specific and limited compared with broad‑spectrum flavor compounds, reflecting its particular sensory characteristics. Like other flavoring substances, cyclohexanone is evaluated based on both its chemical nature and expected exposure. Compounds such as benzaldehyde (almond flavor) and menthol (mint flavor) also undergo safety assessments to determine if typical dietary exposures are within acceptable risk margins. The comparison illustrates how various flavoring agents contribute distinct sensory properties while being subject to similar regulatory scrutiny. Ultimately, flavoring agents share a common framework of evaluation, but their specific contributions to taste and odor distinguish their applications in food products.

Common Food Applications Narrative

Cyclohexanone is incorporated into a variety of food products where complex and nuanced flavor profiles are desired. In beverage applications, flavor scientists may use targeted flavoring agents to achieve specific sensory experiences, such as refreshing aromatic notes in soft drinks or enhanced flavor complexity in functional beverages. In confectionery and baked goods, subtle flavor enhancers like cyclohexanone can contribute to a more balanced or rich profile when combined with natural and other synthetic flavor components. These food categories often rely on precise flavor engineering to meet consumer expectations and differentiate products in a competitive market. In beverage and food formulations, the use of defined flavoring agents is tailored to the specific product matrix. For example, ready‑to‑drink beverages often contain carefully calibrated blends of aroma compounds to influence both the initial aroma upon opening and the sensory perception during consumption. In confectionery products, flavoring agents interact with sugars and other ingredients to deliver a layered taste experience that supports the core product identity. Cyclohexanone’s role in such blends is typically as one of many components that collectively shape the finished flavor. Other categories where targeted flavoring agents are used include dairy analogs, savory snacks, and specialty foods. In these contexts, flavoring agents help create distinct notes or enhance the overall flavor balance, particularly when natural ingredients alone may not provide sufficient sensory impact. The careful integration of flavoring agents into complex formulations underscores the importance of understanding how each component contributes to the final product experience. Cyclohexanone, as a chemically defined flavoring substance, can be part of these sophisticated flavor strategies, allowing formulators to achieve desired taste and aroma outcomes while maintaining regulatory compliance and quality standards.

Safety & Regulations

FDA

  • Notes: Cyclohexanone is permitted under specific use conditions as a solvent in production of microporous polymeric filters under 21 CFR 177.2250, but is not directly approved as a standalone food additive.
  • Regulation: 21 CFR 177.2250

EFSA

  • Notes: Specific EFSA authorization and numeric ADI for cyclohexanone as a flavoring agent not identified in available sources.

JECFA

  • Notes: JECFA concluded no safety concern at current intake levels when used as a flavoring agent, but did not assign a numeric ADI.

Sources

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