E550 - Sodium silicate

At a glance

• What it is: A family of sodium salts of silicic acid; two forms are authorized in the EU—sodium silicates and sodium metasilicate.
• What it does: Anti‑caking agent and processing aid that helps powders stay free‑flowing.
• Where you’ll see it: Dry mixes, powdered seasonings, instant beverage powders, and similar granulated foods.
• Diet notes: Vegan, not an allergen, and the sodium it adds is usually very small.

Why is sodium silicate added to food?

Food makers add E550 to reduce clumping, keep powders flowing, and maintain consistent texture during storage. As an anti‑caking agent, it helps prevent moisture from making particles stick together. In the EU, both sodium silicates (E550(i)) and sodium metasilicate (E550(ii)) are authorized food additives with compositional specifications and permitted uses set in law. ^{1 2}

What foods contain sodium silicate?

You’re most likely to find E550 in dry, powdered, or granulated products where free‑flow is important—such as powdered seasonings, dessert mixes, instant drink powders, dry gravy or soup mixes, and some dry bakery mixes. In the EU, specific food categories and maximum use levels (often “quantum satis,” meaning as much as needed but no more) are listed in Annex II of Regulation (EC) No 1333/2008. Check the ingredient list for “sodium silicate,” “sodium metasilicate,” or “E550.” ²

What can replace sodium silicate?

Depending on the recipe and legal limits, formulators might use other anti‑caking agents instead, such as:

• Silicon dioxide
• Calcium silicate
• Sodium aluminosilicate
• Calcium carbonates
• Sodium ferrocyanide or potassium ferrocyanide in some salt applications

Each option has different strengths (moisture uptake, flow improvement) and permitted uses.

How is sodium silicate made?

Commercial sodium silicate is commonly produced by fusing high‑purity silica sand (silicon dioxide) with soda ash (sodium carbonate) at high temperatures to form a glassy solid, which is then dissolved to make liquid solutions of defined ratios. It can also be made by reacting silica with sodium hydroxide under pressure. ³

Is sodium silicate safe to eat?

In the EU, E550 is an authorized food additive with detailed identity and purity specifications in Commission Regulation (EU) No 231/2012, and its uses are regulated under Regulation (EC) No 1333/2008. These laws set where and how much may be used, reflecting a safety evaluation by European authorities. ^{1 2} In the United States, sodium silicate is permitted as a component of boiler water used to process foods, an indirect use that is also regulated by the FDA. ⁴

Does sodium silicate have any benefits?

For consumers, the benefit is simple: powders pour and measure more easily, and mixes dissolve more consistently. For manufacturers, E550 helps improve shelf stability by limiting moisture‑related clumping.

Who should avoid sodium silicate?

• People avoiding any synthetic additives may choose products without anti‑caking agents.
• Those on strict sodium‑restricted diets should know E550 contributes only a very small amount of sodium at permitted use levels, but can still read labels to be sure. If you have questions about your specific diet, ask a healthcare professional.

Myths & facts

• “It’s just glass, so it must be unsafe.” Sodium silicate is sometimes called “water glass,” but it dissolves in water and is used at very low, regulated levels in foods. ²
• “It’s added for nutrition.” No. It is used for texture and flow, not as a nutrient.
• “Regulators don’t review it.” In the EU, E550 has official specifications and authorized uses under binding regulations. ^{1 2}

Sodium silicate in branded foods

Labeling rules in many markets allow listing by name (“sodium silicate” or “sodium metasilicate”) or by E‑number (“E550”). To check if a product contains it, read the ingredient list on the package. ²

References

Footnotes

1. Commission Regulation (EU) No 231/2012 — Specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩² ↩³

2. Regulation (EC) No 1333/2008 — Food additives (Annex II: Authorized uses). https://eur-lex.europa.eu/eli/reg/2008/1333/oj ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

3. Sodium silicate — Manufacturing/identification information. PubChem, National Institutes of Health. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-silicate ↩

4. 21 CFR 173.310 — Boiler water additives. U.S. Food and Drug Administration (FDA). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-173/section-173.310 ↩