ASCORBYL PALMITATE

CAS: 137-66-6 ANTIOXIDANT

Ascorbyl palmitate is a lipid-soluble ester of L-ascorbic acid (vitamin C) and palmitic acid used primarily as an antioxidant in food and other products to help protect fats and oils from oxidation and maintain product quality.

What It Is

Ascorbyl palmitate is a synthetic antioxidant additive widely used in food and other industries. Chemically, it is an ester formed from L-ascorbic acid and the fatty acid palmitic acid, resulting in a fat-soluble form of vitamin C that functions as an antioxidant. This compound is identified by the CAS number 137-66-6 and is classified in the Joint FAO/WHO Expert Committee on Food Additives (JECFA) database under the functional class "Antioxidant" with the INS number 304i. Its role in food processing stems from its ability to help prevent oxidative degradation of lipids, which can lead to rancidity and undesirable changes in flavor, color, and nutritional quality in foods rich in fats and oils. As a fat-soluble antioxidant, it differs from water-soluble ascorbic acid in that it partitions into lipid phases where oxidative processes are a concern. This additive is also recognized under various synonyms across scientific and regulatory contexts, reflecting its molecular identity and functional usage.

How It Is Made

The production of ascorbyl palmitate typically involves esterification of ascorbic acid with palmitic acid. In this process, the hydroxyl groups of ascorbic acid react with the carboxyl group of palmitic acid under controlled conditions to form the ester linkage that characterizes ascorbyl palmitate. The resulting product is a crystalline powder that is sparingly soluble in water but soluble in lipids and organic solvents, aligning with its intended use in fat-containing food systems. Industrial synthesis routes are designed to maximize purity and yield while meeting specific food-grade specifications, which often include limits on residual solvents, heavy metals, and other impurities. These specifications ensure that the additive performs reliably in food matrices and adheres to regulatory quality standards in jurisdictions where it is permitted for use. The process and quality controls reflect established practices in the manufacture of food additives where consistent functional performance and safety profiles are key considerations.

Why It Is Used In Food

Ascorbyl palmitate is used in food primarily because of its antioxidant properties, which help protect fats and oils from oxidative deterioration. Oxidative rancidity can compromise the sensory qualities of food, leading to off-flavors, discoloration, and loss of nutritional value, particularly in products rich in unsaturated fats. By acting as an oxygen scavenger in lipid phases, ascorbyl palmitate helps extend shelf life and maintain quality in a range of food products, such as edible oils, margarine, and processed foods containing fat components. This functionality makes it valuable to formulators seeking to stabilize products against oxidative damage during storage and distribution. Its lipophilic nature allows it to localize in fat-rich regions where oxidation is most likely to occur, complementing other antioxidants in multi-component systems. The use of ascorbyl palmitate in foods supports consistent product quality and reduces waste by delaying oxidative degradation under typical storage conditions.

Adi Example Calculation

An illustrative example of how an ADI might be considered is when a regulatory body provides a numeric range such as was historically associated with ascorbyl palmitate (for example, a previous JECFA range for ascorbyl palmitate or stearate combined was in the low milligram per kilogram body weight range, but this was superseded by a group classification). In such hypothetical scenarios, a person weighing 70 kilograms would have a theoretical intake limit calculated by multiplying the numeric ADI by body weight if a specific value were defined. Illustrative calculations help stakeholders understand the relationship between regulatory benchmarks and real-world exposure levels, but they should not be construed as recommended intake levels for individuals.

Safety And Health Research

Safety evaluations of ascorbyl palmitate have been conducted by authoritative bodies such as JECFA and the European Food Safety Authority. JECFA’s assessment led to the classification of ascorbyl palmitate and related esters with a group designation rather than a specific numeric acceptable daily intake, indicating that at typical exposure levels from food use the compound is not anticipated to pose health concerns. EFSA’s re-evaluation noted that toxicity data are limited and much of the safety assessment is based on the assumption that the compound is hydrolyzed to its constituent parts, ascorbic acid and palmitic acid, during digestion. The EFSA Panel concluded that available data do not indicate a safety concern at authorized uses and levels. Regulatory risk assessments focus on endpoints relevant to food additive safety, including general toxicity, metabolism, and exposure estimates, rather than direct physiological effects. These evaluations support the conclusion that ascorbyl palmitate’s use in foods, under the conditions observed in regulatory frameworks, is consistent with accepted safety criteria.

Regulatory Status Worldwide

In the United States, ascorbyl palmitate is listed in the Code of Federal Regulations (21 CFR 182.3149) as a substance that is generally recognized as safe when used in accordance with good manufacturing practice, reflecting its authorized status as a food additive. The regulation specifies its name and conditions of use without imposing a numerical maximum level, consistent with typical antioxidant use provisions under GRAS status in food applications. In the European Union, ascorbyl palmitate is authorized under the food additives framework and is assigned the E number E304(i), with specific purity criteria defined in Commission Regulation (EU) No 231/2012. EFSA’s re-evaluation concluded that its use at reported levels does not raise safety concerns for consumers across population groups. Globally, many other regions including Canada, Australia, and New Zealand permit its use under comparable food additive regulations, reflecting a broadly accepted regulatory position driven by scientific assessments of its function and safety. These regulatory frameworks ensure that ascorbyl palmitate can be used to support food quality while conforming to established risk and safety evaluation principles.

Taste And Functional Properties

Ascorbyl palmitate as an additive does not contribute a significant taste of its own at typical use levels. Its primary influence on sensory properties stems from its antioxidant function rather than a direct flavor impact. Because it helps delay the oxidative breakdown of fats, it indirectly supports the maintenance of expected taste profiles in fat-containing foods by preventing the development of off-flavors associated with rancidity. In terms of functional behavior, ascorbyl palmitate is lipid soluble, which enables it to incorporate effectively into fat and oil phases of food matrices where oxidative reactions are prevalent. It demonstrates stability under processing and storage conditions encountered in many food production environments, though it is sensitive to excessive heat, light, and oxygen exposure, which can degrade antioxidant activity. These stability considerations inform how it is handled, formulated, and stored to ensure optimal performance in finished products. Its fat solubility and functional properties make it a versatile component in antioxidant systems, often used in synergy with other antioxidants to enhance overall oxidative stability.

Acceptable Daily Intake Explained

Regulatory bodies use the concept of an acceptable daily intake (ADI) to express the amount of a substance that can be consumed daily over a lifetime without appreciable health risk. For ascorbyl palmitate, JECFA’s evaluation ultimately led to an "ADI not specified" designation in the most recent assessment, which indicates that, based on available toxicological data and expected dietary exposure, a numerical ADI was not considered necessary within the evaluated context. This outcome reflects confidence that typical uses of the additive in food do not result in exposure levels that raise safety concerns. The ADI concept is used in regulatory risk assessments to provide a conservative benchmark for safety evaluation, incorporating uncertainty factors to account for variability among individuals and data limitations. The fact that no specific numeric ADI is specified for ascorbyl palmitate underlines the view that normal dietary exposure through its authorized use in foods is within safe bounds as assessed by expert committees.

Comparison With Similar Additives

Ascorbyl palmitate is often compared with other lipid-soluble antioxidants such as tocopherols (vitamin E) and synthetic antioxidants like butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). Tocopherols are natural antioxidants that also protect lipids from oxidation but are frequently used in combination with ascorbyl palmitate to achieve synergistic effects. Synthetic antioxidants such as BHT and BHA provide robust protection in certain food systems, but some manufacturers prefer antioxidants derived from or related to nutrients like ascorbyl palmitate for consumer perception reasons. Each antioxidant has different solubility, stability, and regulatory status profiles, which influence their selection depending on the specific food application and desired shelf-life outcomes.

Common Food Applications Narrative

Ascorbyl palmitate is applied in a variety of food products where oxidative stability of fats and oils is a priority. In edible oils and margarines, it helps protect unsaturated lipids from oxidation during storage and handling, supporting consistent taste and quality. Processed foods that contain significant fat components, such as baked goods, snacks, and confectionery items with fat inclusions, also benefit from the inclusion of ascorbyl palmitate to delay rancidity and maintain fresh sensory characteristics. In dairy-derived products like butter and cheese spreads, its antioxidant function can contribute to shelf stability, especially in products with extended distribution chains. Ready-to-eat meals and sauces that incorporate vegetable oils may also use this additive as part of a broader antioxidant strategy to preserve quality over time. Across these applications, the goal is to help ensure that the functional and sensory attributes of products are maintained throughout their expected shelf life, aligning with manufacturer and consumer expectations for quality.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 182.3149

EFSA

  • Notes: EFSA concluded no safety concern at authorized uses but did not set a numeric ADI.
  • Approved: True
  • E Number: E304(i)

JECFA

  • Notes: JECFA withdrew the previous numeric ADI and classified group ADI not specified.
  • Ins Number: 304

Sources

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