Messi Biology states that Food Grade Magnesium Sulfate is a refined magnesium sulfate that meets food safety standards. It usually exists as white crystals or powder (most commonly heptahydrate magnesium sulfate and anhydrous magnesium sulfate), also known as “Epsom salt” or “bitter salt,” but must be specifically of food grade quality for food applications.
Main Properties
1. Physical Properties:
- Appearance: Usually colorless or white fine crystals or powder.
- Solubility: Extremely soluble in water (especially in warm water), the aqueous solution is neutral or slightly acidic. Insoluble in ethanol.
- Taste: Has a distinct bitter taste (hence its common name “bitter salt”).
- Hygroscopicity: Heptahydrate magnesium sulfate is easily efflorescent in dry air (losing some water of crystallization) and slightly hygroscopic in humid air.
- Melting Point/Decomposition: Loses water of crystallization at high temperatures and eventually decomposes.
2. Chemical Properties:
- Provides magnesium ions (Mg²⁺) and sulfate ions (SO₄²⁻).
- The aqueous solution is neutral or slightly acidic.
- Can react with certain ions to form precipitates (e.g., barium ions form barium sulfate precipitate).
3. Key Food Safety Characteristics (Distinguishing it from Industrial Grade):
- High Purity: Strictly controls the content of heavy metals (such as lead, arsenic, mercury), toxic impurities, microorganisms, and other harmful substances, ensuring compliance with national or international food additive regulations standards (such as China’s GB 29207, US FCC, EU E 518, etc.).
- Specific Specifications: Strict regulations on its main content (MgSO₄ content), moisture, water-insoluble matter, chlorides, iron salts, clarity, and other indicators to ensure the safety and functionality of its use in food.
Main Applications
1. Food Additive:
- Firming Agent/Stabilizer: This is one of its most traditional food applications.
- Canned/Pickled Vegetables (e.g., Pickled Cucumbers): Adding food grade magnesium sulfate to brine helps maintain the crispness (texture) of vegetables (especially cucumbers). Magnesium ions can combine with pectic substances, enhancing cell wall structure and preventing excessive softening during processing and storage. It is often used in conjunction with other firming agents such as calcium chloride.
- Tofu Coagulation: In some traditional tofu-making processes, it can be used as a substitute or supplemental coagulant for bittern (the main ingredient of which is magnesium chloride), helping soybean protein to coagulate and form. However, it is not as commonly used as magnesium chloride or calcium sulfate.
- Nutrient Fortifier: As a source of magnesium, it is used to fortify foods and beverages, such as: breakfast cereals, nutrition bars, sports drinks, milk powder, foods for special dietary use (such as infant formula, which must be added in strict accordance with regulations and limits).
- Processing Aid: In brewing beer, small amounts are sometimes added to adjust the mineral composition of brewing water (mainly magnesium ions), providing necessary nutrients for yeast, but the dosage must be strictly controlled to avoid excessive bitterness.
2. Epsom Salt (Oral):
- Taken orally after dissolving in water, it uses its high osmotic pressure and the property that magnesium ions are not easily absorbed by the intestine to act as an osmotic laxative, used to relieve occasional constipation. When using, the dosage of the medicine instructions or doctor’s advice must be strictly followed, and excessive use can lead to severe diarrhea, electrolyte disorders (hypermagnesemia), and health risks.
The core value of food-grade magnesium sulfate lies in its high-purity magnesium source and its functionality in specific food processing (mainly firming/stabilizing texture and providing magnesium nutrition). Its application is influenced by its significant bitter taste and strict regulatory restrictions. The most classic application is in maintaining crispness in pickled vegetables and as a nutrient fortifier to add magnesium. When using, be sure to confirm its food-grade status and comply with relevant regulations and safe usage amounts.