CARBON DIOXIDE
Carbon dioxide is a colorless, odorless gas used in food processing and packaging for its antimicrobial, preservative, propellant, and leavening functions, affirmed GRAS in the United States.
What It Is
Carbon dioxide is a simple inorganic compound consisting of one carbon atom covalently bonded to two oxygen atoms, represented by the molecular formula CO2. In food science and regulatory contexts, it is recognized by its Chemical Abstracts Service (CAS) number 124-38-9 and the international numbering system (INS) number 290 as an authorized food additive and processing aid. Carbon dioxide exists as a colorless, odorless, nonflammable gas at ambient temperatures and pressures and can exist as a solid (dry ice) under controlled conditions. Its Other Names include carbonic acid gas and carbonic anhydride, reflecting distinct terminologies used in chemical documentation and industry references. In the context of food ingredients, carbon dioxide is classified under multiple technical functions, indicating its diverse roles in food formulation and processing. These classifications include antimicrobial agent, antioxidant, flavor enhancer, flavoring agent or adjuvant, formulation aid, freezing or cooling agent, direct contact, pH control agent, processing aid, propellant, and solvent. This multiplicity of functional categories underscores its versatility as a gas that interacts with foods in different physicochemical and functional ways. The additive’s identity is codified in regulatory texts such as the United States Code of Federal Regulations, where it is affirmed as generally recognized as safe (GRAS) for direct food use under specified conditions. Applications in food systems range from carbonation of beverages and modified atmosphere packaging to leavening and pH modification. Carbon dioxide’s sensory impact is minimal in terms of odor and flavor in its pure form, but it can influence sensory properties indirectly when dissolved in water or other liquid food matrices, forming carbonic acid which contributes mild acidity. This reactivity is important in beverage carbonation and can influence texture and mouthfeel, a characteristic leveraged in the beverage industry. Its physical properties, including high diffusivity and low solubility relative to other gases, are central to its functional behavior in foods. Overall, carbon dioxide is a well-characterized compound in the context of food science, food technology, and regulatory frameworks, with an established history of safe use in a wide array of food and beverage products.
How It Is Made
Carbon dioxide used in the food industry is typically obtained as a byproduct of various industrial processes rather than through dedicated synthesis. One common source is the combustion of carbonaceous materials or the processing of limestone during lime production, where CO2 is released in significant quantities. In fermentation-based industries, such as brewing and ethanol production, carbon dioxide emerges as a natural metabolic byproduct when yeasts convert sugars into alcohol and carbon dioxide. This fermentation gas can be captured, purified, and compressed for subsequent food and beverage use. Regulatory specifications for food-grade carbon dioxide require that the gas be of appropriate purity and free from contaminants that could negatively impact food quality or safety. Once captured, crude carbon dioxide streams undergo purification steps to remove water vapor, oxygen, hydrocarbons, and other trace impurities. Purification techniques may include scrubbing, compression, and cryogenic separation to achieve high-purity gas suitable for food applications. The processed gas is typically stored and transported in compressed gas cylinders or cryogenic tanks in either liquid or gaseous form. For solid-phase applications, carbon dioxide can be chilled to form dry ice pellets or blocks under controlled pressure and temperature conditions. Dry ice sublimes directly from solid to gas without passing through a liquid phase, which is advantageous in certain refrigeration and shipping contexts. The production and handling protocols for food-grade carbon dioxide are subject to regulatory standards that ensure the gas is free of harmful contaminants and meets purity requirements for intended food uses. These standards are defined in regulatory texts such as the Code of Federal Regulations in the United States. Food manufacturers and suppliers must also follow good manufacturing practice (GMP) to maintain quality throughout the supply chain. Because carbon dioxide participates in multiple functional roles in foods—such as leavening, packaging, and carbonation—the consistency and reliability of its production and purification are critical to achieving consistent results in food processing operations. Industrial practices for carbon dioxide production and purification are well established, given the compound’s extensive use across food and beverage supply chains.
Why It Is Used In Food
Carbon dioxide is used in food systems for a variety of technological reasons that relate directly to its physicochemical properties. One of the primary drivers of its use is its ability to act as an antimicrobial atmosphere when replacing oxygen in packaging. In modified atmosphere packaging (MAP), carbon dioxide can inhibit the growth of aerobic spoilage microorganisms and certain pathogens by creating an environment that is less favorable for their metabolism. This property is especially valuable for extending the shelf life of perishable foods such as meats, cheeses, and fresh produce. In addition to its antimicrobial role, carbon dioxide’s behavior under pressure makes it a preferred gas for carbonated beverages, where its dissolution in liquid imparts the familiar effervescence and mild acidity that characterize carbonated soft drinks, sparkling water, and other fizzy beverages. Another reason carbon dioxide is used in food processing is its function as a leavening gas. In bakery applications, controlled release of carbon dioxide from chemical leavening systems contributes to the rise and porous structure of products such as cakes, quick breads, and certain pastries. In these contexts, carbon dioxide interacts with other ingredients to expand doughs and batters during baking. Furthermore, carbon dioxide is used as a propellant in aerosolized food products, where it assists in delivering fine droplets of food ingredients in applications such as whipped toppings or aerosolized seasonings. Its inert properties and relatively low solubility in fats and oils make it useful in these systems. In addition to these roles, carbon dioxide serves practical functions such as pH control and cooling. When dissolved in aqueous food systems, it forms a weak carbonic acid which can lower pH slightly, influencing flavor and microbial stability. Carbon dioxide’s high heat of sublimation allows it to serve as a cooling agent in the form of dry ice, enabling rapid chilling and freezing during processing or shipment of temperature-sensitive products. Collectively, these rationales reflect carbon dioxide’s utility as a multifunctional additive that supports food preservation, sensory attributes, textural properties, packaging performance, and processing efficiency across a wide range of applications.
Adi Example Calculation
To illustrate how acceptable daily intake (ADI) concepts apply in the context of food additives, consider a hypothetical scenario involving a compound that does have a defined ADI. For example, if an additive has an ADI of X milligrams per kilogram of body weight per day, a person weighing 70 kilograms would have an allowable exposure of 70 times X milligrams per day without expected health risk. This type of calculation helps regulators and manufacturers estimate whether typical dietary exposure falls within safe limits. In contrast, carbon dioxide does not have a defined ADI because it is a naturally occurring gas and is rapidly eliminated from the body through respiration. Because carbon dioxide’s physiological handling is efficient and because typical dietary exposure from foods and beverages is low relative to environmental and metabolic sources, regulatory bodies have not established an ADI. Therefore, an illustrative calculation for carbon dioxide would not yield a numeric dietary limit as it does for other additives with defined ADIs. Instead, the guiding principle is that carbon dioxide should be used according to good manufacturing practices, meaning that usage levels are limited to those necessary to achieve a specific technological effect in food processing or formulation. For consumers and industry stakeholders, it is important to recognize that ADI concepts are applied on a case-by-case basis depending on toxicological evidence, exposure scenarios, and regulatory judgments. In the case of carbon dioxide, regulatory decisions reflect confidence that typical exposure patterns associated with food additive use do not pose health concerns and therefore do not necessitate a numeric ADI. This distinction underscores how regulatory frameworks balance scientific evidence with practical use considerations in ensuring food additive safety.
Safety And Health Research
Regulatory evaluations of carbon dioxide consider its chemical properties, exposure scenarios, and typical uses in food systems. Carbon dioxide is a naturally occurring compound in the atmosphere and is also produced endogenously in the human body as a result of cellular respiration. Because of its natural occurrence and rapid physiological elimination through respiration, carbon dioxide’s toxicity profile in food contexts is largely related to respiratory exposure at high concentrations rather than dietary ingestion. As such, food safety assessments focus on its role in food systems and the likelihood of exposure through consumption of carbonated beverages or foods processed with carbon dioxide rather than systemic toxicity. Health and safety regulatory assessments include consideration of how carbon dioxide interacts with food matrices and whether its use could lead to harmful levels of residual gas or metabolites. In typical food applications, carbon dioxide dissolves or dissipates without leaving harmful residues, and established regulatory provisions such as GRAS status in the United States reflect a consensus that carbon dioxide does not pose a safety concern when used according to good manufacturing practices. JECFA’s evaluation of carbon dioxide did not establish an ADI, indicating that a formal limit was not deemed necessary based on available data and typical exposure patterns. Regulatory evaluations also consider potential effects in special populations, but because carbon dioxide exposure through food is generally low relative to physiological handling capacity, there is no specific evidence-based guidance for populations such as children or pregnant individuals regarding dietary exposure to carbon dioxide when used as an additive. Safety research typically emphasizes occupational and environmental exposures, where high concentrations of carbon dioxide in air can lead to respiratory discomfort and other effects, and appropriate controls are recommended in industrial settings. In dietary contexts, the ingestion of carbon dioxide in carbonated foods does not result in systemic accumulation, as the gas is released through the digestive process or expired through respiration. Therefore, regulatory evaluations prioritize usage conditions that ensure carbon dioxide is applied in ways consistent with established technological functions and does not exceed levels necessary for those functions. Continued surveillance and scientific inquiry support ongoing safety assurance, but there is no indication from authoritative evaluations that carbon dioxide used as a food additive poses a direct toxicological hazard at levels associated with normal consumption patterns.
Regulatory Status Worldwide
In the United States, carbon dioxide is affirmed as generally recognized as safe (GRAS) for use in food under regulations codified at 21 CFR 184.1240. This regulation specifies that carbon dioxide, identified by its CAS number 124-38-9, can be used in food with no limitations other than current good manufacturing practice, supporting roles such as a leavening agent, processing aid, propellant, aerating agent, and gas within food systems. The regulation requires that carbon dioxide be of a purity suitable for its intended use, and its GRAS status means that it is recognized by scientific experts as safe under the conditions of its intended use without the need for premarket approval. The text of 21 CFR 184.1240 provides explicit detail on these points and is a primary US regulatory reference for carbon dioxide’s authorized uses. Internationally, carbon dioxide appears on the Codex General Standard for Food Additives (GSFA) as additive INS 290 with provisions for its use under conditions of good manufacturing practice in a wide array of food categories. The GSFA database enumerates specific food categories where INS 290 can be applied, indicating global acceptance of this additive within food systems under harmonized conditions. The presence of carbon dioxide in the GSFA reflects international consensus on its role and safety when used appropriately in foods and beverages. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has evaluated carbon dioxide and, according to available evaluations, did not specify an acceptable daily intake (ADI) given its ubiquitous nature and wide margin of safety in typical food uses. Regulatory frameworks in other regions may incorporate carbon dioxide under similar provisions, often aligning with Codex and JECFA evaluations. However, specific limits or categorizations may vary based on regional food additive legislation. Collectively, these regulatory touchstones confirm that carbon dioxide is accepted as a legitimate food additive and processing aid in many jurisdictions worldwide, provided that its use adheres to prescribed good manufacturing practices.
Taste And Functional Properties
From a sensory perspective, carbon dioxide in its pure gaseous form is essentially odorless and has no intrinsic taste perceptible to humans. However, when dissolved in aqueous systems such as beverages, carbon dioxide interacts with water molecules to form carbonic acid, which imparts a mild acidity and a distinct tingling sensation on the palate. This sensory effect is a key aspect of consumer experience for carbonated beverages, where the presence of carbon dioxide contributes to perceived freshness and mouthfeel. The effervescence—tiny bubbles that effuse from solution as pressure is released—is a defining characteristic of carbonated drinks and influences flavor perception indirectly by modulating the delivery of aromatic compounds to the olfactory receptors. Carbon dioxide’s functional properties extend beyond sensory contributions. Its solubility in water is pressure-dependent, which means that under high pressure, significant amounts of carbon dioxide can be dissolved. This pressure-solubility relationship is exploited in beverage carbonation and in certain food processing operations that rely on gas infusion to achieve textural effects. Additionally, carbon dioxide is a non-reactive gas in many food matrices, making it useful as an inert blanket atmosphere to displace oxygen and reduce oxidative reactions that lead to rancidity and spoilage. This inertness also makes it suitable for use as a propellant in aerosolized food products where reactive gases could interact unfavorably with food components. The physical behavior of carbon dioxide—such as its ability to transition between gas and solid (dry ice) without a liquid phase at atmospheric pressure—has important practical implications in cooling and freezing applications. Dry ice’s sublimation property allows for rapid temperature reduction without leaving liquid residue, which is advantageous in shipping frozen goods or achieving quick cooling during processing. These combined sensory and functional properties of carbon dioxide make it a versatile additive in food and beverage manufacturing, supporting a range of technological effects from sensory enhancement to preservation and processing facilitation.
Acceptable Daily Intake Explained
An acceptable daily intake (ADI) is a regulatory concept that represents the amount of a substance that can be consumed daily over a lifetime without expected adverse health effects. ADIs are typically established by expert panels based on toxicological data and exposure assessments. In the case of carbon dioxide, authoritative evaluations such as those by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) have not specified a numeric ADI, which reflects the fact that carbon dioxide is a naturally occurring gas in the environment and is produced endogenously by metabolic processes. Because carbon dioxide is rapidly eliminated through respiration and because typical dietary exposure from carbonated products or foods processed with carbon dioxide does not lead to accumulation, regulatory bodies have not identified a need for a formal ADI. It is important to understand that the absence of a defined ADI does not imply that an ingredient can be used without regard for good manufacturing practice. Instead, it reflects regulatory judgment that typical uses of carbon dioxide in food do not present safety concerns at levels consistent with current technological applications. In practical terms, good manufacturing practice means that carbon dioxide is used at levels necessary to achieve its intended technological effect—such as carbonation, preservation, or leavening—without excess. Regulatory frameworks such as the United States Code of Federal Regulations (21 CFR 184.1240) specify conditions under which carbon dioxide’s use is affirmed as safe, emphasizing that its usage should adhere to industry practice. Consumers encounter carbon dioxide in many foods and beverages throughout their daily lives, often without any need for conscious consideration of its presence. The regulatory approach to carbon dioxide exemplifies how safety evaluation can acknowledge the natural physiological handling of a compound, its established use patterns, and the absence of demonstrable adverse effects at typical exposure levels. In this way, carbon dioxide’s regulatory profile illustrates how ADIs function as part of a broader risk assessment framework that integrates toxicology, exposure science, and technological necessity.
Comparison With Similar Additives
Carbon dioxide shares functional space with several other food additives that influence preservation, texture, and sensory properties in foods. For example, nitrogen (INS 941) is another inert gas used in food packaging environments to displace oxygen and extend shelf life, particularly for products such as chips or roasted nuts. Like carbon dioxide, nitrogen does not impart flavor and acts primarily through its physical presence to reduce oxidative spoilage. However, nitrogen’s lower solubility in water compared to carbon dioxide means it does not contribute to carbonation or acidity, making carbon dioxide more suitable for beverage applications where effervescence is desired. Another additive with overlapping functions is nitrous oxide (INS 942), which is used as a propellant in aerosolized whipped toppings. Nitrous oxide provides a specific textural effect due to its solubility in fats and ability to create fine aeration in dairy or alternative products. While both nitrous oxide and carbon dioxide can serve as propellants, their functional niches differ: carbon dioxide is more often used in applications involving gas dissolution in aqueous systems or environmental modification, whereas nitrous oxide is selected for its compatibility with lipid-rich matrices and specific gas retention properties. A third comparison is with inert packaging gases such as argon, used in niche contexts where oxygen exclusion is critical. Argon’s higher density makes it effective in displacing air in packaging, but unlike carbon dioxide, argon does not dissolve in liquid to any significant extent and therefore has no sensory impact in carbonated beverages. In each case, these additives illustrate how different gases are selected based on their physical properties, solubility, and interaction with food components. Carbon dioxide’s versatility—contributing to sensory, preservation, and processing functions—distinguishes it from other gases used in food systems, even as they share some common technological roles.
Common Food Applications Narrative
Carbon dioxide is widely applied across many categories of foods and beverages due to its multifunctional utility. One of its most recognizable applications is in the carbonation of beverages such as sodas, sparkling waters, and other fizzy drinks. Here, carbon dioxide is dissolved in liquid under pressure to create effervescence and mild acidity that define the sensory experience of these beverages. Beyond drinks, carbon dioxide plays a role in the production of bakery goods where it acts as a leavening gas in certain formulations, contributing to the texture and volume of products such as quick breads and cakes. Modified atmosphere packaging (MAP) is another common application where carbon dioxide is used to preserve products such as meats, cheeses, and fresh produce. By displacing oxygen within packaging, carbon dioxide helps slow oxidative processes and inhibits the growth of aerobic spoilage microorganisms, extending the shelf life of these perishable items. In addition to preservation, carbon dioxide is used in applications that require controlled cooling or freezing. Dry ice—solid carbon dioxide—is frequently used to maintain low temperatures during shipping and storage of frozen foods, providing a dry, residue-free cooling medium. Other areas where carbon dioxide contributes include its use as a propellant in aerosolized food products, pH control in beverage systems, and as a solvent in certain extraction processes where an inert gas environment is beneficial. These diverse applications reflect carbon dioxide’s role in both everyday and specialized food products, making it an additive encountered by consumers in numerous contexts, from their morning carbonated beverage to packaged ready-to-eat foods and temperature-sensitive frozen products.
Safety & Regulations
FDA
- Approved: True
- Regulation: 21 CFR 184.1240
EFSA
- Notes: EFSA-specific numeric approval and ADI status not verified from authoritative EFSA evaluation.
- E Number: E290
JECFA
- Notes: JECFA evaluation did not specify an ADI according to the d JECFA database.
- Ins Number: 290
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