CITRAL PROPYLENE GLYCOL ACETAL

CAS: 10444-50-5 FLAVORING AGENT OR ADJUVANT

CITRAL PROPYLENE GLYCOL ACETAL is a synthetic citrus-flavored compound used in flavor formulations and classified as a flavoring agent or adjuvant.

What It Is

CITRAL PROPYLENE GLYCOL ACETAL is a synthetic organic compound used as a flavoring agent or adjuvant in foods. Chemically, it is a 1,3-dioxolane derivative formed from citral and propylene glycol and is characterized by a citrus-like aroma. It is identified by CAS number 10444-50-5 and appears in flavoring substance listings under regulatory code 172.515 in the U.S. regulatory framework. The compound is sometimes referred to by other systematic names that reflect its structure and functional groups. Its primary role in food applications is to impart or enhance citrus and related flavor notes due to its chemical similarity to natural citrus components. The compound belongs to a broader class of flavoring substances called synthetic flavoring agents, which are formally recognized and regulated for use in foods under specific safe-use conditions. CITRAL PROPYLENE GLYCOL ACETAL differs from simple flavoring extracts because it is synthesized to achieve more consistent sensory properties and stability. As a cyclic acetal, it is generally less volatile and more stable than its precursor, citral, under specific processing and storage conditions. This structural benefit allows formulators to use it in applications where the volatile parent compound may be unsuitable due to rapid loss of aroma or sensitivity to heat and air exposure. Although it is frequently mentioned in flavor industry databases and regulatory listings, its detailed safety assessment by international bodies such as JECFA and EFSA is not as widely documented or publicly accessible as that of widely used natural extracts.

How It Is Made

CITRAL PROPYLENE GLYCOL ACETAL is synthesized by reacting citral, a natural aldehyde with a strong citrus aroma, with propylene glycol under acid-catalyzed conditions. This reaction forms a five-membered dioxolane ring, which characterizes the compound’s structure. The acetalization process typically requires a catalyst and the controlled removal of water to drive the equilibrium toward product formation. In industrial practice, this reaction is carried out in a solvent system that facilitates water removal and yields a product that can be further purified, often by distillation or similar separation methods. The starting materials—citral and propylene glycol—are chosen for their availability and reactivity, with the citronellal-derived citral providing the sensory foundation and propylene glycol enabling acetal formation. Citral itself is derived from natural sources such as citrus oils or produced synthetically. The synthesis aims to yield a stable flavoring compound that retains citrus character while improving on the limitations of citral, such as susceptibility to oxidation and volatility. After synthesis, the product is typically subjected to quality control measures to ensure it meets purity specifications for flavor use. This includes testing for residual reactants, byproducts, and compliance with regulatory standards for flavoring substances.

Why It Is Used In Food

CITRAL PROPYLENE GLYCOL ACETAL is used in food primarily to impart citrus-like flavor notes and enhance the sensory profile of food products. Flavor chemists often choose this compound because its structure conveys stability and consistent flavor release compared to some natural citrus aldehydes. Adding it in small amounts can help provide desirable lemon, orange, or citrus characteristics without introducing variability that can occur with natural extracts. Its stability under processing conditions is a key reason for use; it is designed to resist extreme changes that might degrade a natural flavor compound. This allows manufacturers to create flavor systems that perform consistently across batches and different storage conditions. In commercial flavor formulation, the compound may be combined with other flavoring substances to achieve a balanced and appealing taste profile. Because flavor perception is highly sensitive to minor chemical variations, manufacturers value such compounds for controlled and predictable results in products.

Adi Example Calculation

Because a specific numeric Acceptable Daily Intake (ADI) for CITRAL PROPYLENE GLYCOL ACETAL has not been explicitly established by a documented regulatory evaluation in public databases, it is not appropriate to present a detailed numerical example for this compound. The ADI concept involves using an accepted numeric value to estimate safe intake for a given body weight, but without an established ADI for this ingredient, such illustrative calculations cannot be reliably grounded in authoritative evidence. Instead, for compounds with defined ADIs, the calculation typically involves multiplying the ADI (expressed in milligrams per kilogram of body weight per day) by a hypothetical body weight to estimate a daily intake threshold. In situations where ADI data are not available for a specific flavoring substance, regulatory use is focused on good manufacturing practice and limiting use to levels that achieve the desired sensory effect without unnecessary excess in food products.

Safety And Health Research

Safety assessments for flavoring agents such as CITRAL PROPYLENE GLYCOL ACETAL typically consider toxicological data for similar chemical classes rather than extensive data for every individual compound. Flavor industry reference lists often include the compound and provide identifiers for regulatory use, but they do not necessarily represent comprehensive safety evaluations. Toxicological research commonly examines parameters such as acute toxicity, effects on organ systems, and potential for sensitization or irritation in test systems relevant to ingestion. It is important to emphasize that while regulatory listings permit use under defined conditions, detailed peer-reviewed toxicological data specific to this compound may be limited or proprietary. In the absence of robust published safety studies specific to this compound, regulatory frameworks generally require that flavoring agents meet food-grade specifications and are used at levels that do not pose risk to consumers under typical dietary exposures. As with many synthetic flavoring substances, any use must conform with good manufacturing practices, which implicitly integrates safety considerations based on experience with related compounds and historical data used by regulatory bodies.

Regulatory Status Worldwide

In the United States, CITRAL PROPYLENE GLYCOL ACETAL is listed under the category of synthetic flavoring substances and adjuvants permitted for direct addition to food under 21 CFR 172.515. This regulation outlines that such compounds may be safely used in food provided they are used in the minimum quantity necessary to achieve the intended effect and conform to principles of good manufacturing practice. It does not itself assign a numeric permissible level. This regulatory listing indicates U.S. recognition for use as a flavoring agent under specified conditions. The inclusion in this regulatory section reflects historical agency evaluations of similar synthetic flavoring substances in terms of safety for consumption under typical usage patterns. U.S. regulation requires that all flavoring agents meet food-grade specifications and follow labeling requirements for additive use. At the international level, detailed evaluations by bodies such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA) for this specific compound are not readily published in accessible summaries. While industry references may assign a flavor industry number (FL-No) and note status under global reference lists, comprehensive safety evaluations with numeric ADI values and formal opinions may be limited or not widely disseminated. Similarly, European regulators including EFSA may not have issued a formal opinion specific to this compound. Regulatory frameworks outside the U.S. often follow a similar risk-based approach, evaluating substances for use based on available toxicological information and exposure assessments, and typically require compliance with good manufacturing practices in flavor use contexts.

Taste And Functional Properties

The taste and sensory properties of CITRAL PROPYLENE GLYCOL ACETAL are dominated by citrus-like notes, often described as lemon, orange, or general citrus aroma and flavor. Its functional role is to contribute to the overall flavor complexity in food and beverage formulations. Due to its chemical structure, it is more stable than simple aldehydes like citral under typical food processing conditions, which can include heat, light, and oxidative environments. This stability makes it particularly useful in applications where flavor retention over time is important. The compound’s solubility profile tends to favor alcohols and glycol-type solvents, and it has limited water solubility. This influences how food technologists incorporate it into aqueous systems versus emulsified or alcohol-containing products. Its relative stability to pH changes and resistance to rapid deterioration make it a functional choice in a variety of manufactured food systems, although its use levels must still respect regulatory guidelines for flavoring agents. The compound does not contribute to texture or nutritional value but is intended exclusively for sensory enhancement.

Acceptable Daily Intake Explained

An Acceptable Daily Intake (ADI) is a concept used by regulatory and scientific bodies to define the amount of a substance that can be consumed daily over a lifetime without appreciable health risk. ADIs are typically established when sufficient toxicological data are available, including studies in animals and, in some cases, human data. For substances like CITRAL PROPYLENE GLYCOL ACETAL, where detailed numeric ADI values have not been explicitly published by international expert committees in readily accessible databases, the ADI is considered undefined in formal regulatory summaries. This does not imply unsafe use but reflects that explicit evaluation and numeric assignment may not be completed or publicly available for this specific compound. When regulators evaluate a flavoring agent and assign an ADI, they incorporate uncertainty factors to account for interspecies differences and variability among humans. In general, an ADI provides context for comparing typical dietary exposure estimates to levels considered safe, but in the absence of a defined ADI value for this compound, the emphasis remains on ensuring usage at minimum effective levels and in conformity with good manufacturing practice.

Comparison With Similar Additives

CITRAL PROPYLENE GLYCOL ACETAL can be compared to other synthetic flavoring acetals and citrus-derived flavor agents that serve similar purposes in food formulation. For example, simple acetals of aldehyde flavor compounds, such as ethyl vanillin propylene glycol acetal, also provide stable sensory characteristics and can withstand processing conditions. These compounds share functional similarities in providing predictable flavor notes and enhanced stability compared to their parent aldehydes. Another point of comparison is with natural citrus extracts, such as lemon oil or citronellal derivatives, which are used to impart citrus flavor. Natural extracts can offer complex sensory profiles, but they often vary due to source variability and may be more sensitive to heat and oxidation. Synthetic acetals like CITRAL PROPYLENE GLYCOL ACETAL aim to offer more consistency and predictable performance. Finally, other synthetic citrus flavor compounds, such as limonene derivatives, may present different aroma profiles and functional characteristics that formulators select based on desired flavor balance and application specifics rather than direct sensory equivalence.

Common Food Applications Narrative

In food and beverage formulation, CITRAL PROPYLENE GLYCOL ACETAL is used in flavor systems that call for citrus character. Products that might contain citrus flavorings include beverages, confections, baked goods, frozen desserts, and savory sauces where a hint of lemon or orange enhances the overall sensory experience. Its inclusion in these applications is typically at levels that contribute to aroma and taste without dominating the formulation. Manufacturers may incorporate this compound in complex flavor blends to provide a foundation for citrus impressions, especially when the formulation demands consistency across production runs. Because the compound is designed to hold up under processing and storage, it allows product developers to achieve repeatable flavor outcomes. While natural citrus extracts are common, synthetic flavoring agents like this can offer cost-effective alternatives that still meet sensory expectations. Its role in consumer food products is to support the desired flavor profile while balancing cost, stability, and regulatory compliance.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 172.515

EFSA

  • Notes: No authoritative EFSA evaluation specific to this compound found

JECFA

  • Notes: No explicit JECFA ADI found in public databases

Sources

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