Magnesium oxide is an internationally recognized food additive with the INS number 530. Its primary role in the food industry is as an anti-caking agent (especially common in table salt). It is also used as an acidity regulator and an important nutrient fortifier (source of magnesium). Its safety has been assessed and approved by international authoritative bodies (JECFA), with an ADI (Acceptable Daily Intake) of “not specified.” However, its specific use must strictly comply with the food regulations of the producing and selling countries. It also has wide applications in the pharmaceutical field. The following is detailed information about magnesium oxide as a food additive (INS 530):
1. Name:
Chinese: 氧化镁 (Magnesium Oxide)
English: Magnesium Oxide
International Number: INS 530
2. Functional Category: Magnesium oxide is mainly used in food as:
Anti-caking Agent: Prevents powdered or granular foods (such as table salt, milk powder, cocoa powder, seasonings, candies, powdered soup mixes, starch, etc.) from clumping, maintaining their free-flowing state. This is its most common function.
Acidity Regulator: Used to neutralize the acidity of food or adjust the pH value to achieve the desired alkaline level.
Nutrient Fortifier: As a source of dietary magnesium, added to foods (such as breakfast cereals, nutrition bars, milk powder, foods for special dietary uses, etc.) to supplement or fortify magnesium content.
Processing Aid: May play an auxiliary role in certain food processing processes.
3. Common Food Applications:
Table Salt (Anti-caking agent): A very common application.
Cocoa Powder, Milk Powder, Powdered Beverages (Anti-caking agent).
Seasonings, Soup Powders (Anti-caking agent).
Candies, Chewing Gum (Anti-caking agent, Acidity regulator).
Breakfast Cereals, Nutrient-Fortified Foods, Foods for Special Dietary Uses (Nutrient fortifier – Magnesium source).
Soy Products (e.g., tofu coagulant, as a substitute or supplement to bittern or gypsum, but this use is more of a processing aid or acidity regulator).
4. Safety:
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has evaluated magnesium oxide (INS 530) and considers it safe within the specified uses and dosages.
JECFA has established an Acceptable Daily Intake (ADI) for magnesium oxide: “Not Specified.” This means that its toxicity is extremely low, and no strict limits need to be set when used in accordance with Good Manufacturing Practices (GMP).
Important Note: Although the ADI is “Not Specified,” as a strongly alkaline substance, excessive intake of magnesium oxide (especially as an antacid or laxative) can interfere with gastric acid and may cause diarrhea (this is the basic principle of its use as a laxative). The amount added in food is usually far below the dose that produces this effect.
5. Regulations:
The scope and maximum usage limits of magnesium oxide (INS 530) are clearly stipulated in the food regulations of different countries/regions (e.g., China’s GB 2760 “National Food Safety Standard for the Use of Food Additives,” EU regulations, US FDA regulations, etc.). Producers must strictly comply with local regulations.
When used as a nutrient fortifier, the amount added is usually determined based on the magnesium nutritional needs of the target population and the nature of the food itself.
6. Relationship and Difference with Magnesium Hydroxide (INS 528):
Both are compounds of magnesium, and their functions in food overlap (anti-caking agent, acidity regulator, magnesium source), but their chemical properties are different.
Magnesium oxide (MgO) is an alkaline oxide that slowly reacts with water to form magnesium hydroxide (Mg(OH)₂).
In terms of anti-caking effect, magnesium oxide (light) has a stronger hygroscopicity due to its loose and porous structure, so it is usually more effective as an anti-caking agent.
As a nutrient fortifier, the magnesium content of magnesium oxide (approximately 60.3%) is higher than that of magnesium hydroxide (approximately 41.7%), meaning that the addition of magnesium oxide can be less to provide the same amount of magnesium.
7. Other Uses:
Widely used in the pharmaceutical field as an antacid (to neutralize stomach acid) and a laxative.
Used industrially as a refractory material, rubber filler, ceramic raw material, etc.