CITRAL

CAS: 5392-40-5 FLAVORING AGENT OR ADJUVANT

Citral is a naturally occurring lemon-scented aldehyde used as a flavouring agent in food and beverages, recognized for its citrus aroma and its inclusion in synthetic flavouring listings.

What It Is

Citral is an organic compound belonging to the class of monoterpene aldehydes. It is defined chemically as 3,7-dimethyl-2,6-octadienal and comprises two geometric isomers, commonly referred to as neral and geranial. This flavouring agent is valued in the food industry predominantly for its distinctive lemon-like aroma, which imparts a fresh, citrus character to a wide range of food products. Citral is also found naturally in many plant essential oils, especially in lemongrass, lemon, and other citrus oils, where it contributes significantly to sensory profiles. In regulatory terms, Citral appears on the U.S. Food and Drug Administration (FDA) list of synthetic flavouring substances and adjuvants that are generally recognized as safe (GRAS) for their intended uses, as enumerated in Title 21 of the Code of Federal Regulations, section 182.60. This listing indicates that, when used in accordance with good manufacturing practice, Citral is accepted as safe for flavouring purposes in food within the United States. Additionally, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) has evaluated Citral and included it among flavouring agents with an established group acceptable daily intake (ADI), providing an international context for its safe use. Other names and synonyms for Citral reflect its chemical structure and isomeric forms, including various systematic and common designations. These alternate names are used in chemical registries and regulatory filings to ensure precise identification across jurisdictions and databases. Citral's CAS number 5392-40-5 uniquely identifies this compound in chemical inventories and scientific literature.

How It Is Made

The manufacture of Citral for use as a flavouring agent typically involves chemical synthesis or extraction followed by purification. Industrial synthesis often starts from terpene feedstocks derived from natural sources such as citronellal or myrcene, which are transformed through controlled oxidation and isomerisation steps to yield the two main isomeric components of Citral, geranial (the trans-isomer) and neral (the cis-isomer). These reactions are carried out under carefully managed conditions to optimise yield and minimise impurities. Extraction from natural plant essential oils represents an alternative route, particularly when a ‘‘natural’’ declaration on product labelling is desired. Plant materials like lemongrass, lemon peel, and Litsea cubeba are steam-distilled to recover volatile essential oils, which contain significant proportions of Citral. Subsequent fractionation and purification steps, such as distillation or chromatography, concentrate the Citral component to meet food-grade specifications. The quality of extracted Citral is influenced by the source material, harvest conditions, and processing techniques. Purity and quality specifications for Citral used in food flavouring are governed by regulatory authorities and industry standards. Specifications include limits on residual solvents, isomer ratios, and contaminant levels to ensure that the compound is suitable and safe for human consumption. Commercial producers often adhere to established analytical methods to verify identity and purity prior to formulation into flavouring preparations. Suppliers may provide certificates of analysis confirming compliance with relevant specifications for food-grade Citral.

Why It Is Used In Food

Citral is incorporated into food and beverage formulations primarily for its potent citrus aroma, which can enhance or impart lemon-like sensory characteristics. This makes it especially useful in products where a bright and refreshing citrus note is desirable, such as in beverages, confectionery, baked goods, and dairy-based desserts. Because of its strength, only small amounts of Citral are needed to achieve the desired flavour profile. In addition to sensory enhancement, Citral may play a functional role in flavour systems by masking undesirable notes from processing or storage. Food manufacturers sometimes blend Citral with other flavour components to achieve a balanced and stable flavour profile that aligns with consumer expectations. Its compatibility with a variety of food matrices, including aqueous and lipid-containing systems, adds to its utility in complex flavour formulations. Citral’s inclusion in flavour blends is guided by regulatory frameworks that define permissible uses and levels. These frameworks, such as the FDA’s GRAS listings and international evaluations by bodies like JECFA, inform manufacturers about acceptable practices when incorporating Citral into foods. Importantly, while it serves flavour functions, Citral does not act as a preservative or nutrient; its role is strictly linked to sensory attributes and formulation aesthetics.

Adi Example Calculation

To illustrate how an ADI can be applied in a hypothetical context, consider an ADI of 0.5 mg per kilogram of body weight per day for Citral expressed as a group ADI. For an adult weighing 70 kilograms, multiplying the individual’s body weight by the ADI yields a lifetime daily threshold of 35 mg of Citral per day (70 kg times 0.5 mg/kg). This calculation assumes daily exposure over a lifetime and uses the upper bound of the group ADI. It is important to emphasise that this is only an illustrative example, not a recommendation of how much Citral a person should consume; actual intake from foods is much lower because Citral is used at minimal levels needed to achieve specific flavour profiles. In practical terms, typical flavoured foods contain Citral in microgram rather than milligram quantities per serving, meaning that normal dietary exposure contributes only a small fraction of the illustrative ADI threshold. Regulatory bodies use intake estimates and exposure assessments to ensure that consumption remains safely below relevant ADI levels across population groups.

Safety And Health Research

Safety evaluations of Citral focus on toxicological endpoints relevant to flavouring agents, including genotoxicity, carcinogenicity, and systemic toxicity. Regulatory bodies such as JECFA review available studies and exposure data to determine whether use levels in food are compatible with consumer safety. In forming its group acceptable daily intake, JECFA considered data on Citral and related compounds, concluding that total dietary intake at typical use levels would not raise safety concerns when compared against the established group ADI. Experimental research on Citral includes studies in laboratory animals examining effects at high doses; these studies help characterize potential hazards and establish thresholds below which no adverse effects are observed. Importantly, the presence of Citral in the FDA’s GRAS list means that recognised experts have evaluated the compound’s safety and concluded that, when used as a flavouring agent at levels consistent with good manufacturing practice, it does not pose an unreasonable risk. Like many flavouring substances, Citral has also been studied for potential skin sensitisation and irritancy. Such data inform labelling and handling guidance in non-food contexts, such as cosmetics. However, in food use, sensory exposure levels are significantly lower and are evaluated within the safety frameworks established by regulatory authorities. The overall body of evidence supports the conclusion that Citral’s use as a flavouring agent is consistent with regulatory safety criteria.

Regulatory Status Worldwide

Citral’s regulatory status reflects evaluations by key food safety authorities in major markets. In the United States, Citral is specifically listed in the Code of Federal Regulations under 21 CFR 182.60 as a synthetic flavouring substance and adjuvant that is generally recognized as safe (GRAS) for its intended use as a flavouring agent in food. This listing means that Citral can be used according to good manufacturing practices without the need for further premarket approval by the U.S. Food and Drug Administration. The CFR listing provides explicit recognition that Citral’s use in food flavouring is acceptable within defined contexts and aligns with long-standing regulatory practice in the United States. Internationally, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated Citral as part of a group of flavouring substances and established a group acceptable daily intake (ADI) of 0-0.5 mg/kg body weight, expressed as Citral, which remains a reference point for evaluating safety. This group ADI reflects comprehensive review of toxicological and exposure data, and provides a benchmark against which dietary intake estimates can be assessed. In the European Union, flavouring substances like Citral are evaluated and authorised under regulations governing food flavourings, and inclusion in the Union list of flavourings requires compliance with specific conditions of use. EFSA’s flavouring evaluation framework and the Union list provide the basis for determining whether substances such as Citral are permitted in food products sold within EU Member States. While an E-number specific to Citral is not widely referenced, regulatory structures make provision for chemcially defined flavourings under applicable legislation.

Taste And Functional Properties

Citral is prized for its sensory characteristics, which are dominated by a strong, fresh citrus aroma reminiscent of lemon peel. Organoleptically, it provides a bright and sharp impression that can lift or accentuate citrus profiles in food products. Its sensory impact is often described as sweet, sharp, and reminiscent of natural citrus, making it a key component in citrus-flavoured products. Functionally, Citral is relatively volatile, which contributes to its strong aroma, but also means that it can be lost during high-temperature processing. Formulators often account for this by adjusting levels or using encapsulation techniques to protect the compound during baking or other heat-intensive steps. Citral is soluble in various solvents used in flavour formulation, including ethanol and certain glyceride bases, but has limited solubility in water; this characteristic affects how it is incorporated into different product systems. In terms of stability, Citral can be sensitive to light, heat, and oxygen, which can lead to oxidation or isomerisation over time. Manufacturers typically recommend storage in cool, dark conditions and incorporate antioxidants where appropriate to maintain stability. Regulatory considerations also influence functional usage; good manufacturing practice calls for using the lowest level necessary to achieve the desired effect while maintaining compliance with safety and labelling requirements.

Acceptable Daily Intake Explained

An acceptable daily intake (ADI) is a regulatory tool used by food safety authorities to describe the amount of a substance that can be consumed every day over a lifetime without appreciable risk to health. For Citral, JECFA has established a group ADI for Citral and related flavouring compounds, expressed as Citral, reflecting comprehensive assessment of toxicological studies and dietary exposure. This group ADI serves as a benchmark for assessing cumulative exposure from foods containing Citral and similar substances. It is important to understand that an ADI is not a recommended intake level or a target for consumption; rather, it represents a conservative estimate of exposure that regulators consider to be without appreciable health risk. When food manufacturers use Citral in flavour formulations, they do so at levels well below those that could approach the ADI, taking into account typical consumption patterns and flavour potency. ADIs incorporate safety factors that account for uncertainties in experimental data, ensuring a wide margin between levels associated with potential adverse effects in studies and those encountered through normal dietary intake.

Comparison With Similar Additives

Citral can be compared with other citrus-related flavouring agents, such as limonene and linalool, which are also used to impart citrus notes in food and beverage products. Limonene, a naturally occurring terpene found in citrus peels, provides a bright, citrus aroma but differs structurally as a hydrocarbon rather than an aldehyde; this leads to distinct olfactory characteristics. Like Citral, limonene is listed as GRAS in the United States and is widely used in flavour formulations. Linalool, another terpene alcohol, offers a softer floral-citrus aroma that can complement stronger citrus notes. Both limonene and linalool are evaluated by regulatory bodies as flavouring substances and are included in regulatory listings similar to Citral. Comparisons among these compounds illustrate how food formulators select specific agents based on desired sensory outcomes and regulatory parameters. These related additives often appear together in flavour blends to achieve complex sensory profiles while remaining within regulatory frameworks that guide safe use.

Common Food Applications Narrative

Citral’s distinctive lemon-like aroma and flavour have made it a versatile ingredient in a broad range of food and beverage products. In beverages, especially those with citrus notes such as lemonades, limeades, and citrus-flavoured sparkling drinks, Citral contributes a fresh, zesty profile that enhances the overall sensory experience. Its use in soft drinks and juices helps create consistent and appealing flavour character across production batches. Confectionery manufacturers also employ Citral in candies, chews, and gummy sweets to provide clear citrus notes. In baked goods, including biscuits, cakes, and pastries, Citral can be used to reinforce fruit flavours or to provide a complementary citrus layer in complex flavour blends. Dairy products such as ice cream or yogurt may incorporate Citral as part of natural or synthetic citrus-flavoured formulations, adding a refreshing contrast to creamy textures. Citral is also found in sauces, dressings, and marinades where the citric character supports overall flavour balance. In savoury applications, it may be blended with other flavouring agents to provide nuanced accents that complement herbs or spices. Across these applications, manufacturers consider both sensory goals and regulatory frameworks to determine appropriate use levels, ensuring that products meet both consumer expectations and safety standards.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 182.60

EFSA

  • Notes: EFSA specific approval status for Citral as a flavouring is not clearly identified in available sources.

JECFA

  • Year: 2003
  • Adi Display: 0-0.5 mg/kg bw
  • Adi Mg Per Kg: 0.5

Sources

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