What it is
The salt is made by reacting a magnesium source such as magnesium carbonate or hydroxide with food-grade citric acid, then crystallising or spray drying the product. Depending on drying conditions the result is either the anhydrous tribasic salt or the nonahydrate, and the two are not interchangeable on a weight basis. Both are tested for assay, elemental magnesium, residual chloride and sulphate, and heavy metals.
Formulation considerations
The single most common error with this ingredient is formulating to a magnesium target without confirming which hydrate is in the drum, since the difference in magnesium per gram runs to several percentage points. Beyond that, the material behaves agreeably: solubility in water is moderate and improves in an acidic base, solution pH sits near neutral, and the flavour contribution is a mild saline-citrus note rather than the bitterness or chalkiness of oxide and hydroxide forms. In dry blends the main risks are moisture pickup in the anhydrous grade and segregation where particle size differs sharply from the carrier. Because citrate chelates divalent cations, interaction with other mineral salts in a premix is worth checking where several are present at high inclusion.
Applications
Magnesium citrate appears in hydration and electrolyte drink powders, effervescent tablets and sticks, magnesium tablets and capsules, vitamin and mineral premixes, gummies, and sports recovery blends. Available in bulk quantities, with pricing on application.
Applications
- Drink powders and sachets
- Effervescent tablets and sticks
- Tablets and capsules
- Electrolyte and hydration formulations
- Vitamin and mineral premixes
- Gummies and chewables
Handling and storage
Store in sealed original packaging below 25°C in a dry area with relative humidity under 60%. Typical shelf life is 36 months unopened. The anhydrous grade is hygroscopic and will gain weight and cake on exposure to humid air, which affects both assay and flow, so limit open time and reseal liners. Hydrate state should be confirmed before formulating to a magnesium target.
Common questions
How much elemental magnesium does magnesium citrate contain?
The anhydrous tribasic grade typically carries 14% to 16.5% elemental magnesium. The nonahydrate carries roughly 11% to 12%. Dose calculations must use the figure for the specific hydrate and lot, as confirmed on the Certificate of Analysis.
How does magnesium citrate compare with magnesium oxide in a formulation?
Magnesium oxide is far denser in magnesium, at around 60%, so it fits a smaller tablet, but it is poorly soluble and strongly alkaline. Citrate is more soluble, closer to neutral and gentler on flavour, at the cost of a much larger inclusion weight for the same magnesium.
Is magnesium citrate suitable for an effervescent drink?
Yes, and it is widely used there. It dissolves well in the acidic base created once citric acid and bicarbonate react, and it contributes less of the chalky note associated with oxide and carbonate forms.
Should the anhydrous or the nonahydrate grade be specified?
Anhydrous gives more magnesium per kilogram and suits tablets and capsules where space is tight. The nonahydrate dissolves faster and is often preferred in drink powders. Both are available; nominate the grade when enquiring.