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E551
EU Food Additive Code
0.5–2%
Typical Use Level
>99.8%
SiO2 Purity
Applications · Food & Feed

Fumed Silica Anti-Caking Agent for Food & Animal Feed

Food-grade fumed silica (E551 / silicon dioxide) is a globally approved anti-caking additive that keeps powdered foods free-flowing and clump-free. From table salt and powdered sugar to spice blends and animal feed, SEMISIL grades deliver consistent flowability at minimal dosage while meeting EU, FDA, and international food safety standards.

E551 Food Grade Anti-Caking Powder Flow Animal Feed FDA EU Compliant
Overview Applications Benefits Grades Regulations FAQ

What Is Fumed Silica in Food (E551)?

Fumed silica, designated as E551 (silicon dioxide, SiO₂) in European food legislation, is an ultra-pure amorphous silica produced by flame hydrolysis at temperatures exceeding 1000°C. The process yields a nanoscale, high-surface-area white powder with primary particle sizes of 7–40 nm and a BET surface area of 100–400 m²/g. Because it is produced by vapor-phase synthesis rather than precipitation or extraction, it contains virtually no crystalline silica, heavy metals, or mineral impurities, making it suitable for direct food contact and consumption.

The anti-caking mechanism relies on the extraordinary surface area and geometry of fumed silica nanoparticles. When blended at low loadings into a host powder, the nano-particles deposit on the surfaces of larger host particles, physically spacing them apart and preventing moisture bridges from forming between them. This reduces both the Carr Index (a measure of compressibility) and the Hausner Ratio (a measure of interparticle friction), resulting in significantly improved powder flowability, hopper discharge, and filling uniformity even under high-humidity storage conditions.

Common food and beverage applications where fumed silica is used as an anti-caking agent include: table salt, powdered sugar and icing sugar, coffee creamers and whiteners, infant formula and baby food, spice blends and seasoning mixes, baking pre-mixes, whey protein powders and sports nutrition products, and instant soup and sauce powders. It is also widely used in animal feed manufacturing to improve flowability in feed mills and maintain pellet integrity during storage and transport.

Food & Feed Applications

SEMISIL food-grade fumed silica is used across a broad range of powder processing environments. Six primary application areas are highlighted below.

Table Salt

Prevents moisture-induced caking during bulk storage and distribution. Keeps salt free-flowing from shakers and dispensers in humid climates.

Powdered Sugar & Confectionery

Maintains fine, uniform texture and prevents lumping in icing sugar, fondant dusting powder, and confectionery coatings.

Spice Blends & Seasonings

Ensures free-flow performance in high-humidity food service environments and during high-speed bag filling and portioning.

Infant Formula & Baby Food

Ultra-pure grade with tightly controlled trace metal content. Meets the highest purity requirements for the most sensitive consumer category.

Protein Powders & Sports Nutrition

Improves scoop-ability and dissolution rate of whey, casein, and plant-based protein powders. Prevents bridging in hoppers during blending.

Animal Feed

Improves pelleting efficiency and powder flowability in feed mills. Reduces dust generation and maintains even ingredient distribution in compound feeds.

Technical Benefits

Fumed silica offers a combination of performance, purity, and regulatory acceptance that is difficult to match with alternative anti-caking agents such as tricalcium phosphate, calcium silicate, or magnesium carbonate.

  • Ultra-low dosage (0.5–2%)

    Effective at minimal use levels. The high surface area means a very small quantity of fumed silica is sufficient to coat host particles and deliver full anti-caking performance, minimizing any impact on taste, texture, or mouthfeel.

  • High purity (>99.8% SiO₂)

    Low heavy metal content (As, Pb, Hg) meets the strictest food safety specifications including Ph. Eur., FCC, and JECFA purity requirements. Full analytical certificates available per batch.

  • Inert chemistry

    Fumed silica does not react with food components. It contributes no flavor, color, odor, or nutritional value. Its chemical inertness makes it compatible with acidic, alkaline, and hygroscopic food matrices.

  • Broad humidity resistance

    Anti-caking performance is maintained across a wide range of relative humidity, from 20% to 85% RH, enabling consistent product quality in tropical climates and refrigerated distribution environments alike.

  • Regulatory acceptance

    Approved under E551 (EU Regulation 1333/2008), FDA GRAS status (21 CFR 172.480), JECFA food additive specification, and GB 2760 (China). Accepted in most major markets worldwide with a well-established safety record.

Recommended Grades

SEMITECH offers hydrophilic fumed silica grades optimized for food and feed applications. All grades are manufactured under food-grade quality management systems with full traceability and batch-specific documentation.

Grade BET Surface Area Treatment Best For Max Dosage (EU)
SEMISIL 200 200 m²/g Hydrophilic General food powders, spices, salt 10 g/kg (E551)
SEMISIL 300 300 m²/g Hydrophilic High-moisture powders, protein blends 10 g/kg (E551)
SEMISIL 150 150 m²/g Hydrophilic Animal feed, bulk commodity powders Per feed regs
Regulatory dosage note: EU Regulation (EC) No 231/2012 limits E551 to 10 g/kg in most food categories. The FDA allows silicon dioxide up to 2% in food by weight (21 CFR 172.480). Always verify dosage limits for your specific food category before formulation.

Regulatory Overview

Fumed silica as silicon dioxide (E551) is one of the most widely approved food additives in the world. The following summary covers the three major regulatory frameworks relevant to SEMITECH customers.

EU — E551

Regulation (EC) No 1333/2008 Annex II. Maximum 10 g/kg in most dry food categories including seasonings, dried herbs, salt, and powdered products. EFSA-assessed; GRAS status confirmed by EFSA opinion on silicon dioxide.

USA — FDA GRAS

21 CFR 172.480. Permitted as a food additive (anti-caking agent) at a maximum of 2% w/w in food. GRAS notification status. Widely used in US food manufacturing without additional approval requirements.

China — GB 2760

Listed as an approved anti-caking agent in the Chinese national food additive standard GB 2760. Dosage limits are specified per food category. Import documentation and COA with Chinese labeling may be required.

Documentation Available from SEMITECH

  • Certificate of Analysis (COA)

    Full analytical data per batch: SiO₂ content, BET surface area, pH, moisture, heavy metals (As, Pb, Hg, Cd), and sieve residue.

  • Heavy Metals Analysis

    Dedicated heavy metals certificate complying with Ph. Eur. 4.1.2, FCC monograph, and JECFA specifications for food-grade silicon dioxide.

  • Microbiological Certificate

    Total viable count, E. coli, Salmonella, and mold/yeast counts per batch to satisfy food ingredient supplier audit requirements.

  • REACH Declaration

    Confirmation of REACH compliance and SVHC (Substances of Very High Concern) status for EU customers and their regulatory submissions.

  • Regulatory Compliance Letter

    Signed letter confirming compliance with EU 1333/2008 (E551), FDA 21 CFR 172.480, and/or GB 2760 as required by customer quality systems.

Need food-grade silicon dioxide documentation?

Request COA, regulatory compliance letters, and samples for your food or feed application.

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Frequently Asked Questions

Is fumed silica the same as silica gel in food packaging?
No. Fumed silica (E551) is an anti-caking additive that is consumed with the food product as an ingredient. Silica gel is a desiccant packet placed outside the food inside packaging — it is not a food ingredient and is not consumed. Both are forms of silicon dioxide, but they have very different physical structures, surface areas, and uses. Fumed silica is a low-density, high-surface-area nanopowder; silica gel is a granular, porous material used to absorb moisture from the surrounding atmosphere.
What is the maximum permitted level of E551 in food?
Under EU Regulation (EC) 1333/2008, E551 is permitted at a maximum of 10 g/kg in most food categories including seasonings, dried herbs, salt, and powdered food products. The FDA allows up to 2% w/w (equivalent to 20 g/kg) under 21 CFR 172.480. In practice, effective anti-caking dosages are typically 0.5–2%, well below the regulatory maximum in all jurisdictions. Always verify the specific permitted level for your exact food category and target market before formulation.
Does fumed silica affect the taste or nutritional value of food?
No. Fumed silica is chemically inert and does not react with food components under normal processing or storage conditions. It has no flavor, odor, or nutritional contribution (calories, vitamins, minerals). At standard anti-caking dosages of 0.5–2%, it is completely undetectable to consumers and does not change the sensory properties — taste, texture, color, or mouthfeel — of the host product.
What purity standards does SEMISIL food-grade fumed silica meet?
SEMISIL food-grade grades are manufactured to >99.8% SiO₂ purity with tightly controlled heavy metal limits: arsenic (As) <1 ppm, lead (Pb) <2 ppm, mercury (Hg) <0.1 ppm, cadmium (Cd) <1 ppm. Full analytical certificates are issued per production batch, complying with the Ph. Eur. monograph for colloidal silicon dioxide, the FCC (Food Chemicals Codex) specification for silicon dioxide, and JECFA purity criteria for food additive silicon dioxide.
Can fumed silica be used in organic-certified food products?
Fumed silica (silicon dioxide) is permitted in certain organic product categories under EU organic regulation (EC) No 834/2007 and under the USDA National Organic Program (NOP) standards, but restrictions apply by product category and intended use. For example, it may be permitted as a processing aid or anti-caking agent in specific contexts but excluded in others. You should consult your accredited organic certification body for your specific product, application, and target market before use in organic-labeled products.
How is fumed silica different from tricalcium phosphate (TCP) or magnesium stearate as an anti-caking agent?
Fumed silica works by a physical nano-spacer mechanism — the nanoparticles deposit on host powder particles and create a physical barrier that prevents direct particle-to-particle contact and moisture bridging. This mechanism is highly efficient, requiring only 0.5–2% dosage, significantly less than tricalcium phosphate (TCP), which typically requires 1–3%. Unlike magnesium stearate — which is a lubricant that coats particles and can slow dissolution of encapsulated ingredients — fumed silica does not form a hydrophobic coating and does not impair dissolution or disintegration. This makes fumed silica the preferred choice when minimal dosage and maximum anti-caking efficacy are required without compromising downstream powder performance.

Related Resources

Hydrophilic SEMISIL Grades

Full product lineup of hydrophilic fumed silica with BET surface areas from 90 to 380 m²/g. Datasheets and certificates available.

Fumed Silica for Powder Coatings

Technical guide to using fumed silica as a rheology modifier and anti-settling agent in industrial powder coating formulations.

Pharmaceuticals Application

Fumed silica as a glidant and flow aid in tablet and capsule manufacturing. Ph. Eur. and USP grade options covered.

Contact SEMITECH

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