Handbook on Application and Compliance Standards for Food Grade and Pharmaceutical Grade Silicon Dioxide

Part I Compliance Standards and Applications of Food Grade Silicon Dioxide

1. Analysis of EU and US Compliance Standards and Applications of Food Grade Silicon Dioxide (E551)

Food additive E551 (food grade silicon dioxide) is a multifunctional excipient universally used in the global food industry. Compliance certification from the European Food Safety Authority (EFSA) of the European Union and the U.S. Food and Drug Administration (FDA) is the core threshold for products to access the EU and US markets.

Both EU and US regulations mandate that E551 must be amorphous synthetic silicon dioxide with a core purity requirement of ≥99%. Only compliant production processes, namely the fumed process, precipitation process and gel method, are permitted. The raw material must be high-purity quartz sand, and products produced by direct crushing of industrial-grade quartz sand are strictly prohibited.

In terms of heavy metal limits, the general EU and US standards are arsenic ≤3ppm and lead ≤10ppm, which are far stricter than those in most other regions.

Regarding usage specifications, the FDA lists it as a Generally Recognized as Safe (GRAS) substance, stipulating that the maximum addition level as an anti-caking agent shall not exceed 2% of the food weight. The EU sets limits by food category: for most categories, it shall be used at the minimum level required for the intended purpose (quantum satis), while for some powdered foods, the maximum addition level is 15g/kg. It is also mandatory to label "silicon dioxide (E551)" in the ingredient list.

At present, E551 is widely used in the EU and US in fields including solid beverages, dairy products, condiments and baked goods. An addition of 0.5%-1% in instant coffee can improve flowability by 35% and prevent caking during transportation. The precise addition of 0.2%-0.5% in infant formula milk powder can optimize powder dispersibility and ensure uniform mixing of nutrients. The EU and US markets have also launched models with segmented particle sizes for different scenarios, such as 5-10μm for dairy products and 10-15μm for condiments. For export, enterprises must provide a supporting Certificate of Analysis (COA), toxicological reports and process validation documents to ensure full-chain compliance.

2. Interpretation of China's GB 25576 Standard for Food Grade Silicon Dioxide

China's National Food Safety Standard – Food Additive Silicon Dioxide (GB 25576-2020), which replaces the old version GB 25576-2010, is the core compliance basis for the production, sales and application of food grade silicon dioxide. It sets clear and mandatory provisions on product purity, heavy metal limits, production processes, labeling and other aspects.

In terms of product quality requirements, the standard clearly specifies that the silicon dioxide content shall be ≥99.3% for fumed products, and ≥96.0% for precipitated/gel-processed products. It also sets graded limits for loss on drying and loss on ignition. For heavy metal limits, it mandates lead ≤2mg/kg, arsenic ≤1mg/kg, and mercury ≤0.1mg/kg, which are far stricter than the standards for industrial-grade products. In terms of production processes, only three compliant processes are permitted: fumed process, precipitation process and gel method. The raw material must be food-grade high-purity quartz sand, the production environment must meet Good Manufacturing Practice (GMP) requirements, and direct processing of industrial-grade raw materials is strictly prohibited.

In terms of application specifications, products must simultaneously comply with the National Food Safety Standard – Standards for Uses of Food Additives (GB 2760-2024). It is clearly specified that silicon dioxide can be used in more than ten categories of food, including milk powder, egg powder, instant coffee, solid beverages and condiments. Among them, the maximum usage level is 15g/kg for soybean product powder, 1.2g/kg for cereal products, and 1.5g/kg for cocoa products. For most other categories, it can be used appropriately according to production needs, and must be clearly labeled as "silicon dioxide" in the ingredient list. For compliant production, enterprises must establish a full-chain quality control system, and finished products must be provided with a complete COA to ensure that each batch meets the standard requirements.

3. Application of Food Grade Silicon Dioxide in Dairy Products

Food grade silicon dioxide is a key excipient in the processing of powdered dairy products such as milk powder, whey powder and cheese powder. It corely solves industry pain points such as powder caking, poor flowability and unstable nutritional components. Meanwhile, it is chemically inert and will not affect the flavor, color and nutrition of dairy products.

For the stringent requirements of infant formula milk powder, the special silicon dioxide must have a controlled particle size of 5-10μm, a specific surface area of >600m²/g, and a strictly controlled addition level of 0.2%-0.5%. It can form a uniform isolation layer on the surface of milk powder particles to prevent moisture absorption and caking during storage and transportation, while improving powder flowability to ensure accurate and uniform filling and metering. In whey protein powder, an addition of 1%-2% can significantly improve the dispersibility of the product during reconstitution and avoid precipitation and stratification.

The core requirement for silicon dioxide used in dairy products is safety and compliance. Products must pass FDA and EFSA certification, meet the requirements of China's national standard GB 25576-2020, have a total content of heavy metals such as lead, arsenic and mercury ≤5ppm, and the entire production process must be completed in a GMP clean workshop to eliminate cross-contamination. In addition, it can be used as a stable carrier for heat-sensitive ingredients such as vitamins and probiotics, reducing activity loss during processing and extending the product shelf life.

4. Application of Food Grade Silicon Dioxide in Condiments

Food grade silicon dioxide is the core anti-caking agent in the condiment industry, widely used in table salt, chicken bouillon, monosodium glutamate (MSG), spices, compound seasonings and other products. It comprehensively improves product quality and eating experience by optimizing powder flowability and anti-caking performance.

Its core advantage is its strong chemical inertness: it does not react with the components of condiments, does not affect the original flavor of the product, and complies with global food safety standards. In table salt production, an addition of 0.1%-0.5% can effectively prevent moisture absorption and caking in high-humidity environments, keeping the product loose and easy to use. For compound condiments such as chicken bouillon and MSG, it can not only solve the caking problem, but also improve the uniformity of powder mixing to ensure consistent flavor in every bite.

In compound seasonings such as barbecue seasonings and hot pot base mixes, an addition of 1%-2% can greatly improve powder flowability, adapt to the accurate metering and packaging of automated production lines, and significantly increase production efficiency. Special silicon dioxide for condiments usually has a controlled particle size of 10-15μm, a specific surface area of 400-600m²/g, and a heavy metal content ≤1ppm, complying with China's GB 2760-2024 usage standard. It is mostly produced by the precipitation process and washed with ultrapure water to remove impurities, ensuring the product is white, odorless and tasteless.

5. Application of Food Grade Silicon Dioxide in Solid Beverages

Food grade silicon dioxide is a core excipient for solid beverages such as instant coffee, protein powder, meal replacement powder and fruit and vegetable powder. Its core functions are to improve powder flowability, prevent moisture absorption and caking, and enhance dispersibility and solubility during reconstitution. It is pure white, tasteless and odorless, and will not affect the original flavor and color of the product.

In instant coffee production, an addition of 0.5%-1% can improve powder flowability by 35%, prevent caking during storage and transportation, and enable rapid dispersion and dissolution during reconstitution without precipitation or residue. For nutritional solid beverages such as protein powder and meal replacement powder, it can not only improve the dispersibility of the powder during reconstitution and avoid stratification, but also absorb trace moisture in the powder, extending the product shelf life by 6-12 months.

Special silicon dioxide for solid beverages must comply with FDA, EFSA and China's GB 2760-2024 standards, with a controlled particle size of 5-15μm, a specific surface area of 400-800m²/g, and a heavy metal content ≤1ppm, and the entire production process complies with GMP specifications. With the development of solid beverages towards health and functionalization, special models for heat-sensitive ingredients such as probiotics and vitamins have been gradually launched, which can maintain the good processing performance of the product while protecting the activity of nutritional ingredients.

6. Application of Food Grade Silicon Dioxide in the Development of Low-Fat Foods

Food grade silicon dioxide with a multi-level porous structure, relying on its super strong oil adsorption capacity, has become a core excipient in the development of low-fat foods, providing an efficient and safe solution for healthy low-fat diets.

It has a specific surface area of >500m²/g and a well-developed pore structure, with an oil absorption rate more than 30% higher than that of traditional adsorbents. It can reduce the oil content of food while retaining the taste and flavor of the product to the greatest extent. Adding 5%-10% food grade silicon dioxide to the breading mix of fried foods such as fried chicken and french fries can reduce the oil absorption rate of the product by 25%-30%, and reduce the fat content by 3-5g per 100g of product without affecting the crispy taste. In baked goods such as biscuits and potato chips, it can absorb excess oil, reducing the fat content of the product by more than 20%, while optimizing crispness and shelf life.

In emulsified foods such as salad dressing and mayonnaise, it can be used as a thickening and stabilizing agent to maintain the uniform texture and smooth taste of the product while reducing the amount of oil used. Special silicon dioxide for low-fat foods must comply with FDA, EFSA and China's GB 25576-2020 standards, with a purity ≥99.5%, heavy metal content ≤1ppm, and a controlled particle size of 10-20μm. It can be uniformly dispersed in the food matrix without affecting the taste of the product.

7. Application of Food Grade Silicon Dioxide in Flavor Retention

Through entrapment and adsorption effects, food grade silicon dioxide can effectively lock flavor substances in food, prevent aroma loss and degradation during processing, storage and transportation, and is a core solution for the food industry to ensure flavor stability.

Its 2-50nm porous structure and high specific surface area of ≥500m²/g can efficiently adsorb flavor molecules and form a physical protective barrier, avoiding flavor degradation and volatilization caused by high temperature and oxidation. Adding 1%-2% food grade silicon dioxide to baked goods such as coffee beans and bread premix can effectively lock core aroma components such as cafestol and esters, allowing the product to maintain its rich original flavor after 3-6 months of storage.

In food flavors and fragrances, it can be used as a carrier to convert liquid flavor substances into solid powder, greatly reducing flavor volatilization loss while facilitating storage and use. In the production of fruit juice powder and fruit and vegetable powder, it can firmly adsorb volatile aroma components, allowing the reconstituted beverage to restore the original taste of fresh fruits to the greatest extent. Special silicon dioxide for flavor retention must have good adsorption selectivity without adsorbing nutritional components, with a purity ≥99.5%, heavy metal content ≤1ppm, and a controlled particle size of 5-15μm. It can be uniformly dispersed in the food matrix without affecting the taste of the product.

8. Application of Food Grade Silicon Dioxide in Flavor Modulation

Through adsorption, entrapment and sustained release effects, food grade silicon dioxide can precisely regulate the release rate and intensity of food flavor, providing an innovative solution for food enterprises to create differentiated products and customized taste experiences.

Its porous structure and adjustable surface properties can selectively adsorb different flavor molecules, achieving layered release and long-term retention of flavor. In the production of confectionery and chocolate, adding 1%-2% food grade silicon dioxide can entrap flavors and fragrances, allowing the flavor to be released slowly in the mouth and prolonging the taste experience. In functional foods such as health products and nutrition bars, it can effectively mask the off-flavors of functional ingredients such as vitamins and minerals, greatly improving the palatability of the product.

In alcoholic beverages, it can selectively adsorb part of the alcohol substances, reduce the pungency of the wine body, and make the taste softer and smoother. In snack foods, it can create a layered taste experience with top notes, middle notes and base notes by regulating the flavor release rhythm. Special silicon dioxide for flavor modulation must comply with global food safety standards, with a purity ≥99.5%, heavy metal content ≤1ppm, and a controlled particle size of 5-15μm. It can be uniformly dispersed in the food matrix without affecting the taste of the product.

9. Application of Food Grade Silicon Dioxide in the Oil and Fat Industry

In the refining process of vegetable oil, animal fat and edible oil products, food grade silicon dioxide plays core roles in adsorption and impurity removal, decolorization and deodorization, and quality stabilization. It is a key excipient for the oil and fat industry to improve product quality and production efficiency.

It has a high specific surface area of ≥500m²/g and a well-developed pore structure, with super strong adsorption capacity, which can efficiently remove harmful substances and impurities in oils and fats. In the oil refining process, adding 1%-3% food grade silicon dioxide can adsorb impurities such as phospholipids, gums and heavy metal ions in the oil, effectively reduce the acid value and peroxide value of the oil, and improve the purity and transparency of the oil. In the decolorization process, it can be used in conjunction with activated carbon to greatly enhance the decolorization effect, make the oil color more uniform, and at the same time adsorb odor substances to optimize the oil flavor.

In the production of hydrogenated vegetable oil, it can also be used as a catalyst carrier to improve catalytic efficiency, shorten reaction time, and improve the storage stability of the product. Special silicon dioxide for the oil and fat industry must comply with FDA, EFSA and China's GB 25576-2020 standards, with a purity ≥99.5%, heavy metal content ≤1ppm, and a controlled particle size of 10-20μm. It can achieve rapid sedimentation and separation after processing, and will not remain in the finished oil.

10. Application of Food Grade Silicon Dioxide in Pet Feed

Food grade silicon dioxide is a functional additive in the pet feed industry, widely used in dog food, cat food, pet nutritional supplements, snacks and other products. It corely solves the problems of powder moisture absorption and caking, poor flowability and poor palatability. It is safe and non-toxic, complies with the strict global pet food standards, and will not affect pet health.

In the production of dry pet food, adding 0.5%-1% food grade silicon dioxide can effectively prevent the feed from absorbing moisture and caking, keep the product in a loose state, and facilitate pet feeding. At the same time, it can absorb excess moisture and oil in the feed, extend the product shelf life by 6-12 months, and reduce the risk of mold growth. In pet nutritional supplements such as protein powder and vitamin powder, it can significantly improve powder flowability, ensure uniform mixing of nutritional components, and improve the utilization rate of nutrients by pets.

Special silicon dioxide for pet feed must comply with global pet food standards such as those set by the Association of American Feed Control Officials (AAFCO) and the European Pet Food Industry Federation (FEDIAF), with a purity ≥99.5%, heavy metal content ≤1ppm, and a controlled particle size of 10-20μm. It does not affect the palatability of the feed, and the entire production process must be carried out in a GMP clean workshop to eliminate cross-contamination.

Part II Medicinal Functions and Innovative Applications of Pharmaceutical Grade Silicon Dioxide

11. Application of Pharmaceutical Grade Silicon Dioxide in Targeted Drug Delivery Systems

Mesoporous nano-silicon dioxide, with its unique pore structure and excellent biocompatibility, has become an ideal carrier for targeted drug delivery systems (TDDS), providing a core solution for precision medicine.

Its core advantage lies in its precisely adjustable structural parameters: a particle size of 5-10nm, an adjustable mesopore diameter of 2-50nm, and an ultra-high specific surface area of ≥600m²/g. It can efficiently load active ingredients such as anticancer drugs and antibiotics, achieving targeted recognition and controlled sustained release.

In anti-tumor therapy, the drug loading capacity of mesoporous silicon dioxide for hydrophobic anticancer drugs such as paclitaxel and doxorubicin can reach 30%-50%. Through surface modification with targeting molecules such as folic acid and antibodies, the drug targeting efficiency can be increased by more than 3 times. After entering the human body, the carrier can release the drug slowly in response to the pH value of the tumor microenvironment, which not only greatly increases the drug concentration at the tumor site, but also significantly reduces the toxic side effects on normal tissues and decreases the frequency of administration.

In the fields of antibacterial therapy, gene therapy and vaccine delivery, it can entrap drugs to avoid gastrointestinal degradation and improve bioavailability. By adjusting the pore size and surface functional groups, the dosing interval can be extended from 3 times a day to once a week, greatly improving patient medication compliance. At present, injectable grade products have met the standards of the United States Pharmacopeia (USP) / European Pharmacopoeia (EP), with a heavy metal content ≤5ppm. Its functional modification has also become a hot direction in pharmaceutical research and development.

12. Application of Pharmaceutical Grade Silicon Dioxide in Transdermal Drug Delivery Systems

Pharmaceutical grade silicon dioxide plays multiple roles in transdermal drug delivery systems such as gel plasters and patches, including drug loading, penetration enhancement and formulation stabilization. Its excellent adsorption performance and skin compatibility provide an innovative solution for transdermal drug delivery technology.

As a drug carrier, silicon dioxide has a high specific surface area of ≥500m²/g, which can achieve a drug loading capacity of 20%-40%. At the same time, it can protect the active ingredients of the drug from degradation, solving the pain points of low drug loading capacity and easy inactivation of most transdermal drugs. In gel plasters, the addition of 10%-20% pharmaceutical grade silicon dioxide can increase the transdermal absorption efficiency of the drug by more than 30%. Its good thixotropy and adhesion can ensure that the plaster is closely attached to the skin without irritation or sensitization, greatly improving the patient's comfort.

For topical drugs for pain relief, anti-inflammation, hypoglycemia, smoking cessation and other indications, silicon dioxide can achieve continuous and stable drug release, maintain a stable blood drug concentration, and prolong the duration of drug effect. Special silicon dioxide for transdermal drug delivery must comply with USP/EP pharmacopoeia standards, with a purity ≥99.0% and a strictly controlled particle size of 1-5μm to avoid skin irritation. Through surface hydrophilization modification, its compatibility with the gel matrix can be further optimized to form a stable formulation system.

13. Application of Pharmaceutical Grade Silicon Dioxide in Sustained-Release Preparations

With its controllable pore structure and excellent adsorption performance, pharmaceutical grade silicon dioxide has become a core pharmaceutical excipient for oral sustained-release preparations. It can precisely regulate the drug release rate, prolong the duration of drug effect, reduce the frequency of administration, and significantly improve patient medication compliance.

Its core advantage lies in its customizable mesoporous structure (pore diameter 2-50nm) and high specific surface area (≥500m²/g), which can design different drug release profiles according to therapeutic needs. In oral sustained-release tablets and capsules, the addition of 10%-20% pharmaceutical grade silicon dioxide can extend the drug release time from 4 hours to 12-24 hours, allowing the blood drug concentration to be maintained within the therapeutic window for a long time and avoiding side effects caused by peak-to-trough fluctuations.

For chronic disease drugs that require long-term use, such as antihypertensive and hypoglycemic drugs, this sustained-release technology can reduce the frequency of administration from 3 times a day to once a day, greatly improving patient compliance. For antibiotic drugs, it can reduce the direct irritation of the drug to the gastrointestinal tract and lower the incidence of adverse reactions. By adjusting the surface functional groups (hydroxyl, amino, etc.) and pore structure, precise sustained release of different drugs can be achieved to meet diverse therapeutic needs. The products must comply with USP/EP pharmacopoeia standards, with a purity ≥99.0%, heavy metal content ≤5ppm, and good compatibility with pharmaceutical ingredients.

14. Application of Pharmaceutical Grade Silicon Dioxide in Biosensors

With excellent biocompatibility, ultra-high specific surface area and flexible surface modifiability, nano-silicon dioxide has become the core substrate material for biosensors. It can significantly improve detection sensitivity and specificity, providing accurate and efficient detection solutions for medical diagnosis, environmental monitoring and other fields.

Its controllable particle size of 5-20nm and customizable surface functional groups can efficiently immobilize biorecognition elements such as antibodies, enzymes and nucleic acids, solving the pain points of easy shedding of biological elements and weak detection signals of traditional sensors. In medical diagnostic sensors, nano-silicon dioxide immobilized with antigens/antibodies can be used for the accurate detection of biological molecules such as blood glucose, tumor markers and pathogens. Through surface modification with fluorescent molecules or electrochemically active substances, it can convert biological recognition signals into detectable optical/electrochemical signals, increasing the detection sensitivity by 10-100 times. It can realize early and accurate diagnosis of diseases, and also adapt to the rapid detection needs of Point-of-Care Testing (POCT) equipment.

In the field of environmental monitoring, nano-silicon dioxide can immobilize microorganisms or enzymes for the detection of pollutants such as heavy metals and pesticide residues in water, with a detection limit as low as ppb level. Its good chemical stability allows the sensor to maintain stable performance in complex environments, extending the service life by more than 30%. Pharmaceutical grade silicon dioxide for biosensors must meet stringent biosafety standards, with a purity ≥99.9%, heavy metal content ≤1ppm, good compatibility with biological molecules, and no biotoxicity.

15. Anti-Adhesion Application of Pharmaceutical Grade Silicon Dioxide in Capsule Preparations

In the production of capsule preparations, pharmaceutical grade silicon dioxide is the core anti-adherent and glidant. It can effectively solve production pain points such as adhesion between the capsule shell and the contents, and uneven powder filling, greatly improving the production efficiency of preparations and the product qualification rate.

In the hard capsule filling process, only 0.1%-0.3% of pharmaceutical grade silicon dioxide is needed to significantly reduce the friction between the powder contents and the inner wall of the capsule shell, reduce adhesion and jamming, increase the filling efficiency by more than 20%, and raise the filling qualification rate from 95% to over 99%. For moisture-absorbing capsule contents, it can absorb trace moisture in the powder, keep the contents dry and loose, and avoid capsule deformation and powder leakage. In the production of soft capsules, it can be used as a suspension stabilizer to prevent sedimentation and stratification of the contents, ensuring uniform and accurate drug dosage in each capsule.

Special silicon dioxide for capsule preparations must comply with USP/EP pharmacopoeia standards, with a purity ≥99.0%, a strictly controlled particle size of 1-5μm, and a heavy metal content ≤5ppm. The entire production process must be completed in a GMP clean workshop. With the large-scale and automated development of the capsule preparation industry, special models for different dosage forms such as enteric-coated capsules and sustained-release capsules have been gradually launched, which can provide customized solutions for preparation production.

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