FD&C BLUE NO. 2

CAS: 860-22-0 COLOR OR COLORING ADJUNCT

FD&C Blue No. 2 is a certified synthetic blue color additive used to impart blue hues in foods, beverages, and other regulated products. It is a disodium salt of an indigoid sulfonated dye evaluated by international safety bodies.

What It Is

FD&C Blue No. 2 is a synthetic color additive that belongs to the class of indigoid dyes used to impart blue color to a variety of consumables and regulated products. Chemically, it is principally the disodium salt of a sulfonated indigo derivative as defined in U.S. color additive regulations with the CAS Registry Number 860-22-0. The compound is recognized in regulatory listings under identifiers such as C.I. Acid Blue 74, C.I. 73015, and the INS designation 132 in international additive numbering systems. As a color or coloring adjunct, its primary purpose is to provide consistent and vibrant blue coloration in products where visual appeal and uniform hue are technologically necessary. The designation "FD&C" stands for "Food, Drugs & Cosmetics" and indicates that this additive has been subject to regulatory review and is listed in specific sections of the Code of Federal Regulations (CFR) for use under defined conditions. Its identity, purity criteria, and allowed uses are codified in U.S. federal regulations to ensure that substances used to color foods and other products meet defined compositional and impurity limits. This regulatory framing reflects a history of scientific evaluation and administrative oversight, situating FD&C Blue No. 2 within the broader context of synthetic colorants that have been historically evaluated for safety and functional performance. From a chemical perspective, the indigoid structure of FD&C Blue No. 2 distinguishes it from other classes of food dyes, such as azo dyes or anthraquinone derivatives, and this structural class affects its solubility, light absorption properties, and overall color profile. The sulfonate groups increase aqueous solubility, making the colorant suitable for use in a range of water-containing formulations. Its vibrant blue shade has made it a staple in product categories where blue hues are desirable, especially in confectionery, beverages, and other food applications where natural blue alternatives are limited. The regulated use of FD&C Blue No. 2 underscores the balance that food safety authorities seek between functionality and consumer protection.

How It Is Made

FD&C Blue No. 2 is manufactured through a multi-step chemical process starting with an indigo precursor. In industrial practice, the starting material for the synthesis is indigo or indigo paste, which undergoes sulfonation by heating in the presence of concentrated sulfuric acid. This sulfonation reaction introduces sulfonic acid groups onto the indigo core, increasing the water solubility of the resulting molecule and converting it into its disodium salt form through neutralization with sodium-containing reagents. Following the sulfonation step, the reaction mixture is processed to isolate the colorant. This involves dilution, neutralization, and purification techniques designed to remove unreacted starting materials, byproducts, and other impurities. Techniques such as filtration, washing, and recrystallization under controlled conditions are typically employed to attain the product specifications required by regulatory authorities. The purity of the final product is critical and is defined by criteria such as limits on water-insoluble matter and specific related substances. These specifications help ensure that the additive used in food and other applications conforms to recognized quality and safety standards. Quality control tests conducted during manufacture include checks for volatile matter, residual solvents, and inorganic contaminants, as well as specific organic impurities that could arise from incomplete reaction or side reactions. The certification process in regulatory jurisdictions, such as the United States, requires that each batch of FD&C Blue No. 2 be analyzed and certified before it can be marketed for its intended uses. This certification is based on compliance with defined chemical specifications that are intended to minimize the presence of unwanted contaminants and to ensure consistency from batch to batch. Manufacturers of FD&C Blue No. 2 must operate under good manufacturing practice principles, which include monitoring reaction conditions, raw material quality, and cleanliness of processing equipment. The overall production approach seeks to balance efficiency with adherence to regulatory criteria, reflecting the dual needs of industrial chemical synthesis and public safety oversight. The procedural steps in manufacturing also influence the functional performance of the colorant in final applications, as the physical form, particle size, and degree of purification can affect dispersion and color strength in finished products.

Why It Is Used In Food

The use of FD&C Blue No. 2 in foods is driven by its ability to deliver a consistent and appealing blue color that meets specific formulation objectives. Many food products require added color to achieve a desired visual quality, especially in products where natural colors are unavailable, unstable, or inconsistent. For instance, beverages, confections, frostings, and baked goods often incorporate synthetic colorants to achieve bright, uniform hues that are attractive to consumers. The role of color in foods goes beyond aesthetics; it can influence consumer perceptions of flavor, quality, and freshness. A stable color additive such as FD&C Blue No. 2 allows food manufacturers to create and maintain visual appeal across production batches and shelf life. This reliability is particularly important for products aimed at specific market segments where blue shades are associated with novelty or particular flavors, such as berry or tropical fruit analogs. In addition to cosmetic appeal, FD&C Blue No. 2 serves functional purposes in certain formulations. In complex systems, natural colorants may degrade or shift hue under processing conditions such as heat, pH changes, or light exposure. Synthetic colorants like FD&C Blue No. 2 are selected for their relative stability in such conditions, helping products retain their intended appearance over time. This stability is essential in applications like ready-to-drink beverages, gelled desserts, and dairy-based products where processing and storage parameters can challenge color fidelity. The technological function of FD&C Blue No. 2 also extends to the creation of specific color effects when blended with other approved colorants. By combining FD&C Blue No. 2 with red or yellow dyes under controlled conditions, manufacturers can achieve a broader range of hues such as purples, greens, or custom shades for seasonal and specialty products. This versatility supports innovation and variety in product portfolios, enabling brands to differentiate their offerings in competitive markets. Overall, the deployment of FD&C Blue No. 2 in food applications reflects a balance of consumer preference for vibrant color, the need for ingredient stability, and regulatory frameworks that define permissible uses and conditions. The additive’s function as a colorant continues to be relevant in many sectors of the food industry, where visual impact is a key aspect of product appeal and market success.

Adi Example Calculation

To illustrate how an acceptable daily intake (ADI) might be interpreted, consider a hypothetical person weighing 70 kilograms. The ADI for FD&C Blue No. 2, as evaluated by an international expert committee, is expressed as a range. If the upper bound of that range were applied, a 70-kilogram person could theoretically consume up to the product of their body weight and the ADI value without exceeding the safety threshold derived by regulatory scientists. For example, using the upper bound of the acceptable daily intake range, multiplying 70 kilograms by that value provides a figure representing the maximum amount of the additive that could be ingested daily over a lifetime without appreciable risk. This calculation is purely illustrative and does not represent a recommended intake; rather, it demonstrates how regulators translate ADI values into terms related to body weight. Actual exposures from food are typically far lower than this theoretical maximum, and the calculation helps contextualize the safety margin inherent in regulatory evaluations. Such calculations are used by risk assessors to compare estimated dietary exposures for different population groups against established ADIs. Populations with higher intake levels due to food consumption patterns may be evaluated separately to ensure that exposures remain below the ADI. Risk managers can then use these assessments to adjust allowable use levels or implement monitoring programs as needed. The example underscores the conceptual role of ADIs in regulatory risk assessment rather than serving as advice for individual consumption choices.

Safety And Health Research

Safety assessments of FD&C Blue No. 2 have been conducted by multiple authoritative bodies to ascertain whether use as an additive poses any health concerns under conditions of intended use. These evaluations consider a range of toxicological endpoints including absorption, metabolism, potential genotoxicity, chronic toxicity, and carcinogenicity. One of the primary international evaluations by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) examined available data and confirmed an acceptable daily intake range based on available studies, indicating that typical dietary exposures remain below levels of concern. Research data available to regulatory bodies show that FD&C Blue No. 2 and structurally related indigoid compounds are poorly absorbed from the gastrointestinal tract, meaning that the majority of an ingested dose passes through the body without extensive systemic uptake. This pharmacokinetic characteristic can influence the interpretation of toxicological studies, as limited absorption generally reduces systemic exposure to the parent compound. Toxicological studies in animals encompass both short-term and longer-term exposures, with chronic studies designed to detect potential adverse effects over extended periods. These include assessments of organ systems, reproductive endpoints, and any evidence of tumor formation or other pathological changes. In several assessments, including those referenced by EFSA, data did not demonstrate consistent evidence of genotoxicity at doses relevant to regulatory evaluations, further informing risk assessments. While some individual studies have explored high-dose exposures that may exceed conditions of typical human dietary intake, regulatory evaluations emphasize the need to interpret such results in the context of exposure, relevance to human health, and the overall weight of evidence. Regulatory science frameworks differentiate between findings at exceedingly high test doses in animal models versus realistic exposures from food use. Integrative safety evaluations aggregate data across studies to identify whether patterns of toxicity emerge that would warrant regulatory action, and in the case of FD&C Blue No. 2, authoritative evaluations have not identified safety concerns at authorized use levels. It is also important to recognize that safety research on food additives is an evolving field. Regulatory bodies periodically review new data and adjust evaluations as necessary. This includes monitoring scientific literature, reviewing post-market exposure data, and reassessing established ADI values when warranted. The ongoing dialogue between science and regulation reflects a commitment to consumer protection while accommodating technological needs in food manufacturing. Overall, current safety assessments support the continued regulated use of FD&C Blue No. 2 as a color additive when used according to applicable guidelines and specifications.

Regulatory Status Worldwide

FD&C Blue No. 2 is recognized in multiple regulatory frameworks as a color additive permitted for use under defined conditions. In the United States, it is specifically listed in Title 21 of the Code of Federal Regulations at section 74.102 for use in foods, reflecting a formal regulatory allowance for this synthetic dye subject to certification and specifications. Additional sections of the CFR, such as 74.1102, extend its listing to color additive mixtures for ingested drugs consistent with good manufacturing practice, and 82.102 provides related context within color additive listings. These regulatory references establish both identity criteria and usage conditions that manufacturers must follow for compliance. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has also evaluated FD&C Blue No. 2 as part of its global assessment of food additive safety. According to JECFA’s database entry, the committee confirmed an acceptable daily intake range of 0-5 mg per kilogram of body weight, reflecting international scientific consideration of available toxicological data. This ADI reflects a consensus built on available studies and is a benchmark often d in global risk assessments. In the European Union, FD&C Blue No. 2 corresponds to the E number designation E132. Scientific opinions from the European Food Safety Authority (EFSA) have re‑evaluated this additive and noted its safety profile, including historical acceptances of ADI values aligned with JECFA’s evaluations. The EFSA Panel’s assessment supports the continued authorization of E132 within specified conditions, emphasizing that safety concerns are not raised at reported use levels. This regulatory position aligns with broader international practices that consider both toxicological evidence and exposure estimates. Regulatory frameworks outside the U.S. and EU also define conditions for the use of FD&C Blue No. 2 or its equivalents, often referencing international specifications such as those developed by Codex Alimentarius. These specifications include compositional criteria and impurity limits that underpin safety evaluations and compliance standards. While specific allowed uses and maximum levels can vary by jurisdiction, the overarching pattern is that FD&C Blue No. 2 is subject to defined regulatory oversight, reflecting its status as an intentionally added colorant with established identity and quality parameters.

Taste And Functional Properties

FD&C Blue No. 2 primarily contributes color and has negligible direct taste impact when used within regulated levels. Synthetic food colorants such as FD&C Blue No. 2 are typically chosen for their visual properties rather than flavor contribution, and when properly formulated they do not introduce perceptible taste notes to finished products. The lack of flavor interference is an important consideration in applications where the desired taste profile must remain unaltered while achieving a specific color objective. From a functional standpoint, FD&C Blue No. 2 exhibits properties typical of water-dispersible synthetic dyes. Its sulfonate groups confer solubility in aqueous environments, allowing it to dissolve or disperse effectively in products with significant water content, such as beverages, syrups, and gelatin desserts. The solubility characteristics also influence the way this colorant interacts with other formulation components, with effects on viscosity and homogeneity that formulators take into account when designing finished products. The dye’s stability under varying processing conditions—such as temperature changes, pH variations, and exposure to light—is a key aspect of its functional performance. While FD&C Blue No. 2 generally withstands many typical food processing environments, like other colorants it can experience degradation or hue changes under harsh conditions. Manufacturers often consider these properties when selecting colorants for products that undergo thermal processing or extended shelf life. Because FD&C Blue No. 2 does not provide nutritive value and does not significantly alter taste, its inclusion in food systems is strategically focused on visual enhancement. In multi-component formulations, the presence of fats, proteins, or other ingredients can influence how the dye disperses and the intensity of the perceived color. Formulators may adjust dye concentration and processing conditions to achieve uniform coloration that aligns with consumer expectations. In general, FD&C Blue No. 2 is considered functionally effective in a wide range of food matrices, provided that its use complies with regulatory standards and good manufacturing practice. The additive’s behavior in different environments—such as stability in acidic versus neutral pH, interaction with emulsifiers, and impact on product appearance over shelf life—are key considerations in application development. While sensory effects like taste are minimal, the visual influence of FD&C Blue No. 2 plays a significant role in shaping consumer perception and acceptance of colored food products.

Acceptable Daily Intake Explained

An acceptable daily intake (ADI) is a regulatory science construct that represents an estimate of the amount of a substance that can be ingested daily over a lifetime without appreciable health risk. ADIs are established by expert committees based on a comprehensive review of toxicological data, including studies in laboratory animals and, when available, human data. The ADI is typically expressed in units of milligrams of the substance per kilogram of body weight per day. For FD&C Blue No. 2, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated the available data and confirmed a range for the acceptable daily intake. This assessment reflects the committee’s consideration of toxicological studies, exposure estimates, and scientific uncertainty factors built into the derivation of ADI. The ADI range serves as a conservative benchmark to help regulators and risk managers determine whether typical dietary exposures to the additive are within levels considered not to pose appreciable risk. Importantly, the ADI is not a recommended target intake; rather, it is a safety threshold. Typical exposures in the population are generally far below this threshold, meaning that routine consumption of foods containing FD&C Blue No. 2 at levels permitted by regulation does not approach the ADI for the vast majority of individuals. Regulatory bodies use ADIs to guide decisions on allowable use levels, labeling requirements, and in some cases to evaluate whether additional risk management measures are necessary. Consumers may encounter ADI values in regulatory documents or scientific evaluations, but these values are most relevant to risk assessors and food safety authorities. ADIs help inform decisions that aim to protect public health in the context of lifelong exposure, rather than to provide guidance on short-term or occasional consumption. The application of uncertainty or safety factors in deriving ADIs ensures that they remain protective even when data have inherent limitations or variability. The concept of ADI underscores the precautionary approach taken by regulatory science when evaluating substances intentionally added to food.

Comparison With Similar Additives

FD&C Blue No. 2 can be considered alongside other synthetic color additives that serve similar functions in foods and beverages. For instance, FD&C Blue No. 1 is another certified blue dye with different chemical structure and properties but is likewise used to impart blue hues in consumables. While both provide blue coloration, differences in their chemical properties influence how they perform in various pH environments, their stability during processing, and their interactions with other ingredients. Food formulators may choose one over the other based on desired shade and formulation requirements. Other synthetic colorants such as FD&C Red No. 40 and FD&C Yellow No. 5 are frequently used in combination with blue dyes to achieve a broader palette of colors. For example, blending FD&C Blue No. 2 with a red dye can create purple hues in products like frostings or confectionery coatings. Each colorant has its own regulatory specifications and safety evaluations, and formulators must consider these factors when designing multi‑color systems. Natural color alternatives such as spirulina extract or anthocyanins offer blue or purple tones derived from plant sources, but these natural options often differ in stability and hue consistency compared to synthetic dyes. Natural colors may degrade more rapidly under heat or light exposure, making synthetic additives like FD&C Blue No. 2 appealing for applications requiring robust stability. The choice between synthetic and natural colorants reflects a balance of functional performance, regulatory acceptance, and consumer preference. Overall, FD&C Blue No. 2 fits within a suite of color additives that collectively enable a wide range of visual effects in food products. When compared with similar additives, formulators weigh factors such as hue intensity, processing resilience, and regulatory constraints to select the most appropriate colorant for a given application.

Common Food Applications Narrative

FD&C Blue No. 2 finds broad application across a variety of food and beverage categories where an appealing blue hue is desired. In confections, it is regularly used to create vibrant blue coatings on hard candies, gummies, and licorice, helping products stand out on shelves and communicate specific flavor cues to consumers. The visual impact of color in these products is closely tied to their appeal, particularly among children and younger demographics, making FD&C Blue No. 2 a valuable tool for confectionery formulators. In beverages, this colorant helps produce bright and consistent blue shades in sports drinks, flavored waters, and soft drinks. The role of color in beverages extends beyond aesthetics; it can influence perceptions of flavor intensity and quality. Manufacturers often rely on synthetic colors like FD&C Blue No. 2 to achieve stable hues that endure processing and storage while complying with regulatory guidelines. Dairy products and frozen desserts, including ice creams, sherbets, and flavored yogurts, also utilize FD&C Blue No. 2 to create visually appealing offerings. In these formulations, the dye must disperse effectively in complex matrices containing fats and proteins, an attribute that FD&C Blue No. 2 can support when used at appropriate levels. The ability to achieve consistent color in such systems enhances product differentiation and aligns with consumer expectations for novelty and flavor association. Baked goods represent another category where FD&C Blue No. 2 is used to produce striking color effects. Frostings, icings, and decorative cake elements often incorporate this colorant to achieve bold blues that are difficult to obtain with natural alternatives. The increasing interest in themed baked goods—for holidays, celebrations, and special occasions—has sustained demand for dependable synthetic dyes that deliver predictable and intense colors. Beyond these mainstream categories, FD&C Blue No. 2 appears in sauces, dressings, and snack foods where specific color cues support branding and sensory appeal. For example, blue hues can signal particular flavor profiles in ready-to-eat snacks or contribute to playful visual themes in limited-edition products. While natural blue colorants exist, their stability and consistency often do not match synthetic alternatives, reinforcing the functional role of FD&C Blue No. 2 in a wide array of food applications. Across these diverse product types, the use of FD&C Blue No. 2 is governed by regulatory conditions that define where and how it can be incorporated. Food manufacturers integrate this colorant into formulations with attention to both visual outcomes and compliance with applicable additive standards. The versatile applicability of FD&C Blue No. 2 in foods underscores its long-standing role as a staple colorant in the industry.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 74.102

EFSA

  • Approved: True
  • E Number: E132
  • Adi Display: 0-5 mg/kg bw
  • Adi Mg Per Kg: 5

JECFA

  • Year: 2018
  • Ins Number: 132
  • Adi Display: 0-5 mg/kg bw
  • Adi Mg Per Kg: 5

Sources

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