MAGNESIUM HYDROXIDE

CAS: 1309-42-8 COLOR OR COLORING ADJUNCT, DRYING AGENT, NUTRIENT SUPPLEMENT, PH CONTROL AGENT, PROCESSING AID

Magnesium hydroxide is an inorganic compound used in food applications primarily as an acidity regulator and pH control agent under conditions of good manufacturing practice.

What It Is

Magnesium hydroxide is an inorganic chemical compound with the formula Mg(OH)2 and CAS number 1309-42-8. In the context of food additives, it is recognized by regulators as a functional ingredient with multiple technical roles including acidity regulation, pH control, nutrient supplementation, color adjunct assistance, and various processing functions such as aiding drying and stabilizing formulations. Under international additive classification systems, magnesium hydroxide is identified with the INS number 528 and is permitted for use in foods under conditions of good manufacturing practice. It appears as a white, odorless powder that is practically insoluble in water, and its alkaline properties make it effective for adjusting acidity in food systems. Magnesium hydroxide is distinct from other food-grade mineral additives in its ability to neutralize acids without introducing significant flavors or altering food structure beyond its technological purposes. In regulatory inventories such as the United States Code of Federal Regulations, magnesium hydroxide is listed as an ingredient that meets food chemical specifications and may be used in food without quantitative limitations beyond good manufacturing practice. Internationally, it is included in the Codex General Standard for Food Additives (GSFA) Table 3 provisions, which permit its use in a broad range of food categories under defined use conditions. These functional classifications reflect its role as a buffering and stabilizing agent. The compound’s inclusion as a nutrient supplement is based on its contribution of magnesium, an essential mineral in human diets, although its primary adoption in foods is technological rather than nutritional.

How It Is Made

Magnesium hydroxide for food‑grade use is typically produced by precipitating it from aqueous solutions of soluble magnesium salts such as magnesium chloride by the controlled addition of alkali agents like sodium hydroxide, resulting in a fine white precipitate of Mg(OH)2. This precipitate is then washed, purified, and dried to meet specifications for food additive use as outlined in compendia such as the Food Chemicals Codex. In industrial practice, strict quality control measures are employed to ensure that levels of heavy metals and other impurities fall below regulatory limits, ensuring suitability for food applications. The production process begins with raw materials that are generally of high purity and proceeds through controlled chemical reactions that form the hydroxide. The precipitated product is separated from the mother liquor by filtration or centrifugation, followed by drying and milling to achieve the desired particle size and physical characteristics. Food-grade magnesium hydroxide must meet established identity and purity criteria, which are incorporated by reference into regulations such as 21 CFR 184.1428 in the United States. While variations in particle size or morphology may occur depending on processing conditions, the underlying chemistry remains consistent: magnesium ions react with hydroxide ions to form the hydroxide lattice. Manufacturers aim to remove residual salts and inorganic contaminants during processing, and food additive specifications often include limits on elements such as lead and arsenic. The production environment and handling procedures are designed to minimize exposure to contaminants and to ensure that the finished product conforms to the regulatory requirements for food use. This production approach helps maintain the functional performance of magnesium hydroxide in food systems and supports consistent performance across batches.

Why It Is Used In Food

Magnesium hydroxide performs several technological functions in food systems that make it a useful ingredient for manufacturers. Its primary role as a pH control agent and acidity regulator helps stabilize the acidity of formulations, which can be critical for product stability, texture, and shelf life. In foods where slight adjustment of pH is needed to protect flavor or preserve ingredients, magnesium hydroxide provides a controlled alkaline buffering capacity without introducing off‑flavors or reactive species beyond hydroxide ions. Additionally, magnesium hydroxide may serve as a nutrient supplement, contributing magnesium ions to fortified foods or specialized nutritional products. Magnesium is an essential mineral required for many physiological processes, and its inclusion through additives can support targeted nutrient profiles in certain products. In dry food systems, magnesium hydroxide can act as a carrier or drying aid, helping to manage moisture levels and improve handling properties in powdered or dehydrated ingredients. Its classification as a color or coloring adjunct reflects its occasional use in conjunction with other additives to maintain the integrity of pigments or to minimize undesirable visual changes during processing. Because magnesium hydroxide operates under conditions of good manufacturing practice without specific quantitative limits in many jurisdictions, it offers flexibility for formulators to meet technological goals while maintaining compliance with regulatory standards. Its multifunctionality—acidity control, nutrient contribution, and processing support—makes it a valuable tool in modern food formulation.

Adi Example Calculation

This illustrative example explains how ADI considerations might be applied in a hypothetical scenario: For an additive with a numerical ADI, regulators would consider an individual’s body weight to estimate the total daily amount that could be consumed without appreciable risk. For instance, if a compound had an ADI of 10 mg per kg of body weight, a person weighing 70 kg could theoretically consume up to 700 mg per day within the safety threshold. However, for magnesium hydroxide, JECFA’s designation of "not limited" rather than a specific number reflects its low toxicity and the context of its use under good manufacturing practice. In other words, typical intakes from food applications that comply with regulatory conditions are not expected to approach levels of concern, and this type of calculation primarily serves to illustrate how ADIs are used conceptually rather than prescribing a real consumption target. Because magnesium hydroxide’s safety assessments have not established a specific numeric ADI, illustrative examples are based on general ADI principles rather than a defined value. This approach demonstrates how regulatory evaluations compare estimated exposures with safety benchmarks, ensuring that additive use remains within accepted safety margins. Real dietary exposures depend on the specific uses and concentrations of the additive in different food categories, which are controlled by regulations and good manufacturing practice.

Safety And Health Research

Regulatory bodies such as the U.S. Food and Drug Administration and the Joint FAO/WHO Expert Committee on Food Additives have evaluated magnesium hydroxide for safety in food applications. In the U.S., its listing under 21 CFR 184.1428 reflects a determination that it is safe for use in food under conditions of good manufacturing practice. Internationally, organizations such as Codex include magnesium hydroxide in the GSFA database with functional classifications that include acidity regulation and color retention, indicating acceptance of its safety profile in specified uses. The Joint FAO/WHO Expert Committee on Food Additives has assigned magnesium hydroxide the INS number 528 and classified it functionally as an acidity regulator and color retention agent. Historical JECFA evaluations indicate that an acceptable daily intake (ADI) was considered "not limited," a designation used by JECFA for additives of very low toxicity that do not require a numerical ADI value, provided they are used in accordance with good manufacturing practice. This classification is consistent with regulators’ acknowledgment that magnesium hydroxide’s physicochemical properties and metabolic fate support its safe use at levels typical of food applications. Scientific assessments of magnesium hydroxide in regulatory contexts focus on its technological function and low oral toxicity relative to typical exposures from food use. Research supporting its safety includes studies of its chemical inertness in food matrices, its limited solubility that mitigates excessive absorption, and experience with its use in dietary supplements and other consumer products. These evaluations reinforce the conclusion that magnesium hydroxide poses minimal risk when incorporated into food under regulated conditions, although quantitative exposure assessments may vary by food category and consumption patterns.

Regulatory Status Worldwide

In the United States, magnesium hydroxide is affirmed in 21 CFR 184.1428 as an ingredient that meets food chemical specifications and is used in food with no limitation other than current good manufacturing practice, covering roles such as nutrient supplement, pH control agent, and processing aid. This regulatory entry reflects its acceptance for direct use in food under defined conditions of use. It also appears in other U.S. regulatory listings, including 21 CFR 176.180 and 176.210, which reference its permitted use in certain food contact applications under appropriate conditions. Internationally, magnesium hydroxide is recognized in the Codex General Standard for Food Additives (GSFA), where it is included in Table 3 provisions, allowing its use in a range of food categories under conditions of good manufacturing practice. The GSFA listing specifies it as an acidity regulator among other functional classes, providing a global framework that supports its food additive use across jurisdictions that adopt Codex standards. In the European Union, magnesium hydroxide is listed with the E number E528 in the Union list of authorized food additives under Regulation (EC) No 1333/2008, indicating approval for use as an acidity regulator and related functions. National food standards in other regions also recognize magnesium hydroxide for similar technological roles, with specific conditions and use levels defined by local authorities. These regulatory frameworks collectively support the use of magnesium hydroxide as a multifunctional additive under appropriate conditions of good manufacturing practice.

Taste And Functional Properties

Magnesium hydroxide itself is essentially tasteless when used at the low levels typical of food additive applications. Its contribution to sensory characteristics is generally minimal, although its alkaline nature means that excessive amounts could impart slight bitterness or chalkiness if not properly balanced within a formulation. In practical terms, food technologists use magnesium hydroxide to adjust pH without significantly affecting flavor profiles, which is particularly valuable in beverages, dairy products, and confections where sensory integrity is important. Functionally, magnesium hydroxide exhibits low solubility in water, which helps maintain product stability in systems where limited dissolution is preferred. Its physical form as a fine powder allows it to disperse uniformly in dry mixes, aiding in moisture control and reducing caking. In acidic environments, the hydroxide reacts to neutralize excess acid, contributing to a more stable pH range that can protect flavor compounds and improve texture. These properties also make it useful in preventing unwanted chemical reactions that can arise from overly acidic conditions. The compound’s heat stability further supports its use in processes that involve thermal treatment, as it does not degrade or lose functionality at moderate processing temperatures. While magnesium hydroxide does not contribute flavor or aroma itself, its ability to influence pH and stabilize product structure indirectly supports desirable sensory outcomes in finished foods. Because it is used in relatively small amounts under good manufacturing practice, its impact on taste and texture remains subtle and controlled.

Acceptable Daily Intake Explained

The acceptable daily intake (ADI) concept represents the amount of a substance that can be consumed every day over a lifetime without appreciable risk, based on comprehensive toxicological data. For magnesium hydroxide, historical evaluations by the Joint FAO/WHO Expert Committee on Food Additives have indicated that an ADI is "not limited," meaning that no specific numeric ADI value was established due to low toxicity and limited concern at the levels used in food. This designation implies that typical consumption from food additive use does not raise safety concerns when magnesium hydroxide is employed according to good manufacturing practice. It is important to understand that an ADI is not a target or recommended intake level; rather, it serves as a safety benchmark used by regulators to assess exposure in relation to potential health effects. In practical terms, magnesium hydroxide’s inclusion in regulatory listings and international standards reflects confidence in its safety profile for the technological purposes it serves, including acidity regulation, nutrient supplementation, and processing support. Because its use levels in food are controlled through regulatory frameworks and good manufacturing practice, routine exposure from foods is generally far below levels associated with any potential adverse effects identified in toxicological studies. The "not limited" designation by JECFA reinforces the low safety concern associated with magnesium hydroxide at use levels typical of food applications.

Comparison With Similar Additives

Magnesium hydroxide shares functional similarities with other mineral-based food additives used for pH control and acidity regulation, such as calcium hydroxide (INS 526) and sodium hydroxide (INS 524). Calcium hydroxide also serves as an acidity regulator and firming agent in food systems, and its higher solubility relative to magnesium hydroxide can make it more suitable for certain applications where rapid dissolution is needed. Sodium hydroxide, another common pH regulator, is highly soluble and effective at neutralizing acids, but it must be used with caution due to its strong alkaline nature and potential to significantly alter flavor or texture if not precisely controlled. Compared to organically derived acidity regulators like citric acid, mineral hydroxides offer a neutral flavor profile and stable buffering capacity, but they do not contribute acids to the system. Citric acid, by contrast, lowers pH and can introduce sourness as well as participate in flavor interactions. In applications where a mild increase in pH is desired without impacting flavor, mineral hydroxides are preferred. Magnesium hydroxide’s relatively low solubility also differentiates it from more soluble bases, resulting in a more gradual pH adjustment that can be beneficial in certain food matrices. These comparisons highlight how formulators select specific additives based on functional needs, solubility profiles, and sensory considerations while maintaining compliance with regulatory standards.

Common Food Applications Narrative

Magnesium hydroxide finds use across a variety of food products where its technological functions are needed. In dry powdered foods such as dairy mixes, bakery mixes, or powdered beverages, it serves as a buffering and anti‑caking agent, helping to maintain free‑flowing properties and consistent reconstitution behavior. Its role in acidity regulation means it can be incorporated into certain beverage formulations to achieve a targeted pH range that supports overall quality and consumer perception. In dairy and dairy‑based desserts, magnesium hydroxide may contribute to stabilizing pH and supporting texture development during processing and storage. Bakery products can benefit from pH control to support leavening and crumb structure, and magnesium hydroxide’s buffering capacity can aid in achieving these outcomes. In cheese and cheese‑based products, acidity regulation is important for controlling microbial activity and ensuring consistent texture. Magnesium hydroxide may be used to fine‑tune pH during production, helping to maintain product quality. In confectionery, it can support processing by adjusting pH without introducing undesirable flavors or interfering with sugar crystallization. Fortified foods and nutritionally enhanced products may incorporate magnesium hydroxide as a source of magnesium, contributing to the nutritional profile of specialty products without significantly altering other ingredients. Across these applications, regulators permit magnesium hydroxide under conditions of good manufacturing practice, allowing food manufacturers to leverage its multiple functionalities to meet product quality goals while complying with safety and labeling requirements.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 184.1428

EFSA

  • Notes: No specific numeric ADI shown in toxicological evaluations
  • Approved: True
  • E Number: E528

JECFA

  • Notes: JECFA designation of not limited is shown but no specific year provided
  • Ins Number: 528
  • Adi Display: NOT LIMITED

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