Highly soluble magnesium oxide for the food and supplement industry
What is magnesium oxide?
Magnesium oxide is a chemical compound with the formula MgO. Magnesium oxide is inorganic, consists of white crystals, and is normally insoluble in water. It has a high elemental magnesium content of approximately 58–60 % and can be used in food supplements where space is limited, such as tablets or capsules. It is also often used to increase the magnesium content in products that cannot be achieved with purely organic magnesium sources alone.
Overview:
- Magnesium oxide, consists of a magnesium cation (Mg²⁺) and an oxygen anion (O²-)
- Molecular weight: 40.3 g/mol
- Bulk Density: 150–850 g/L (depending on product)
- Formed by calcination of magnesium hydroxide or magnesium carbonate
- Mineral content in %: Approx. 60 %
How is magnesium oxide produced?
Magnesium oxide is formed by calcination (heating a chemical compound below its melting point to cause partial chemical decomposition) of magnesium hydroxide (Mg(OH)2) or magnesium carbonate (MgCO3). The calcination temperature has a significant influence on the properties of magnesium oxide (MgO).
In which industries and for which products can magnesium oxide be used?
In medicine, it is used as an antacid and source of magnesium. In the food industry, it is registered as a food additive E530, serves as a pH regulator and is also approved for the fortification of food products and supplements with magnesium.
1. Crystal structure and phase purity:
- Low temperatures: At low calcination temperatures, an amorphous magnesium oxide is often obtained
- Medium temperatures: At these temperatures, well-crystallized MgO is usually produced. The structure becomes denser and more crystalline, which can improve the mechanical properties
- High temperatures: Very high calcination temperatures lead to a further increase in crystallinity. The resulting MgO is very stable and dense.
2. Particle size and surface structure:
- Low temperatures: The resulting MgO often has a high specific surface area. This leads to a higher reactivity, as more surface area is available for chemical reactions.
- High temperatures: The specific surface area decreases. This can reduce the reactivity of the MgO.
3. Porosity:
- Low to medium temperatures: MgO calcined at lower temperatures tends to have a higher porosity, which makes it suitable for use as a catalyst or adsorbent.
- High temperatures: Porosity decreases as the particles become denser and the pore structure partially closes. This can increase the density but reduce the specific surface area and porosity.
4. Reactivity and solubility:
- Low temperatures: Due to the higher specific surface area, the MgO is more reactive and easier to dissolve.
- High temperatures: MgO calcined at higher temperatures has a lower reactivity and solubility.
In which food supplements is magnesium oxide typically used?
Our Innova market research has shown that magnesium oxide is mainly processed in tablets and capsules (see chart below). This is because magnesium oxide is ideal for this dosage form, as its high elemental magnesium content requires only a small of the raw material compared to other forms of magnesium compounds. By using our highly soluble magnesium oxide, effervescent tablets and powder can be added to the range of useful dosage forms.
Why is the solubility of magnesium important for liquid applications?
Especially in liquid applications or dissolution applications, the consumer expects a residue and sediment-free solution. Product developers therefore often look for mineral compounds that meet these requirements. In the past, the poor solubility of magnesium oxide in water posed problems for the food and supplement industry. We have now found a solution to this problem with our highly active and soluble magnesium oxide.
What makes our magnesium oxide a highly soluble magnesium oxide?
In tests with magnesium oxides in effervescent powders, we found that a highly active magnesium oxide variant dissolves sediment- and residue-free during the dissolution time of the effervescent powder. The reason for this is the citric acid added to the solution. It causes the solution to acquire an acidic pH value and improves the ionization (dissolution) of the magnesium oxide. This solubility described in this experiment is also transferable to the much stronger stomach acid. The highly soluble magnesium oxide can be dissolved (ionized) by gastric acid, too, and thus, is bioavailable. The described highly soluble magnesium oxide can therefore be used in both dry and liquid applications. Due to the high elemental magnesium content, only small quantities of our highly active soluble magnesium oxide need to be applied to achieve the desired magnesium content in the end application.
Bioavailability of magnesium oxide
In general, regular magnesium oxides have very limited bioavailability due to their poor solubility. By improving the solubility, the bioavailability is also increased – as seen in the example of our highly soluble magnesium oxide above. The bioavailability of magnesium oxide can also be influenced by the dosage form. A study shows that the bioavailability of magnesium oxide in effervescent tablets is twice as high compared to magnesium oxide in capsules. This suggests that the dissolution of magnesium oxide in water (ionization to Mg2+) is an important prerequisite for its absorption. Consequently, the bioavailability of dissolved/ionized magnesium oxide is comparable to that of organic magnesium salts (e.g. magnesium citrate, magnesium gluconate, etc.). These findings apply to the highly active magnesium oxide from MAGNESIA. This product offers good solubility in diluted organic acids such as citric acid or malic acid, which are mainly used as acidifiers in food supplements. This makes our highly soluble magnesium oxide ideal for effervescent powders and tablets, which always contain an acid component per se.
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Source: MAGNESIA, Highly soluble magnesium oxide for the food and supplement industry, website https://magnesia.de/en/nutritional-health-supplements/highly-soluble-magnesium-oxide/