50 Core Q&As and Popular Science on Food-Grade Silica Gel

I. Basic Cognition Chapter

1.What is food-grade silica gel?

Food-grade silica gel (commonly known as food-grade silica) is an amorphous white powdery inorganic compound with the chemical formula SiO₂. It is prepared through specific purification processes, featuring stable chemical properties and excellent adsorption performance. As a legal additive, it is widely used in the food industry, with the international code E551.

2.What are the core differences between food-grade silica gel and industrial-grade silica gel?

The core differences lie in purity, safety, and application: Food-grade silica gel must meet strict food additive standards (e.g., lead content ≤ 3mg/kg), only contains an amorphous structure, and has no carcinogenic risks; industrial-grade silica gel may contain crystalline silica (such as quartz) and harmful impurities, mainly used in construction, chemical engineering, and other fields, and is strictly prohibited for use in food.

3.Does food-grade silica gel exist in nature?

Yes, it does. It widely exists in the Earth's crust, such as quartz sand and diatomite. However, natural silica needs to undergo purification, impurity removal, and other processes to meet food-grade purity standards before it can be used in the food industry.

4.What are the key physical properties of food-grade silica gel?

Its main properties include: insoluble in water and most acids (only soluble in hydrofluoric acid and strong alkalis), rich in microporous structures inside, large specific surface area, strong adsorption capacity, and the ability to form an isolation film on the surface of powder particles, with both moisture-proof, anti-caking, and stabilizing functions.

5.Is there a difference between colloidal silica gel and ordinary food-grade silica gel?

Colloidal silica gel (prepared by the vapor-phase method) is a high-end category of food-grade silica gel. It has finer particles (nano-scale) and higher purity. In addition to anti-caking, it can also be used as a thickener to improve food texture, and is widely used in dairy products and health products.

II. Production Process Chapter

1.What are the main processes for preparing food-grade silica gel?

There are two mainstream processes: ① Vapor-phase method: Using high-purity silica as raw material, it is calcined at 1000℃ and then subjected to vapor-phase deposition, resulting in products with high purity and small particle size; ② Precipitation method: Prepared through steps such as leaching, filtration, precipitation, and drying of silicate ores, with lower cost. For example, Solvay's Tixosil® series is produced by this method.

2.How do different preparation processes affect product performance?

Products made by the vapor-phase method have a larger specific surface area (usually > 100m²/g) and stronger adsorption capacity, making them suitable for high-end food and pharmaceuticals; products made by the precipitation method have controllable particle sizes (1-100μm) and lower costs, and are widely used in anti-caking treatment of ordinary powdered food.

3.How is safety ensured in the production process of food-grade silica gel?

During production, it is necessary to strictly control the purity of raw materials (selecting silica with low impurities), optimize process parameters (such as calcination temperature and purification process), and conduct heavy metal detection, crystalline state identification, and other links to ensure that the products meet national food additive standards.

4.What are the technical characteristics of Evonik in the production of food-grade silica gel?

Evonik is good at the vapor-phase method. Its food-grade products are characterized by high purity and narrow particle size distribution, and can be used as stabilizers to uniformly disperse nutrients, which are widely used in vitamin supplements and high-end dairy products.

5.What process does Solvay's Tixosil® series adopt? What are its advantages?

It is prepared by the precipitation method. Its core advantage is that it has both anti-caking properties and compatibility: it can not only prevent powder caking and improve fluidity but also coexist well with active ingredients and flavor substances in food, making it suitable for scenarios such as baking powder and condiments.

III. Safety and Health Chapter

1.Is food-grade silica gel safe for the human body?

It is recognized as safe by international authoritative institutions: JECFA (Joint FAO/WHO Expert Committee on Food Additives) classifies it as a safe additive. The EFSA (European Food Safety Authority) assessment in 2024 confirmed that it has no safety risks for all populations, including infants and young children, under normal usage.

2.Will food-grade silica gel accumulate in the human body?

No, it will not. It has stable chemical properties and cannot be digested and absorbed by the human body. It will be completely excreted from the body through feces, with no risk of accumulation in the body, and no toxicity or nutritional impact.

3.Why is crystalline structure prohibited in food-grade silica gel?

Crystalline silica (such as quartz) has a sharp structure, and long-term inhalation may cause diseases such as pulmonary fibrosis; while food-grade silica gel is all amorphous, with no such health risks. The EU requires that its crystalline content must be less than 1%.

4.Is there a tolerable daily intake (ADI) limit for food-grade silica gel?

Currently, there is no clear ADI value. JECFA and EFSA believe that it has extremely high safety and no specific upper limit for intake needs to be set, but it is emphasized that "the dosage should be reduced as much as possible on the premise of achieving the expected purpose".

5.Is there a risk of excessive intake of food-grade silica gel?

It is difficult to take in excessive amounts under normal diet. Although there is no clear toxicity threshold, excessive intake of any substance may cause discomfort. Moreover, food additive use standards strictly limit its addition amount (e.g., the US FDA stipulates that it should not exceed 2% of the total mass of food), which can effectively avoid the problem of excessive intake.

6.Can food-grade silica gel be used in infant food?

Yes, it can. The EFSA's special assessment in 2024 confirmed that using it in infant formula food (such as category FC 13.1.1) at the current dosage will not pose safety risks, and it can improve the fluidity and solubility of milk powder.

7.Do people allergic to silicon need to avoid food containing silica gel?

There is no need to worry too much. Food-grade silica gel is different from organic silicon compounds that cause allergies. Its inorganic structure hardly triggers immune reactions, and there are no reports of clear allergic cases so far.

8.Is there a safety guarantee for heavy metal residues in food-grade silica gel?

There are strict standard limits. China's GB 25576 standard requires lead ≤ 3mg/kg, and arsenic, mercury, etc. must meet the limits. Manufacturers need to conduct testing through technologies such as atomic absorption spectrometry (AAS) to ensure that impurities do not exceed the standards.

9.Are there special risks associated with nano-scale food-grade silica gel?

Currently, there are no clear risks. The EFSA assessment pointed out that although there are detection uncertainties for nano-scale particles, existing data show that they will not be absorbed in the digestive tract, and the exposure level under normal usage will not cause health problems.

IV. Core Enterprises and Products Chapter

1.What is the current status of Rhodia's food-grade silica gel business?

Rhodia has been acquired by Solvay, and its food-grade silica gel product line has been integrated into Solvay's Tixosil® brand system. It continues the original advantages of the precipitation method and focuses on anti-caking solutions in the condiment and baking fields.

2.What layout does Grace have in the field of food-grade silica gel?

Grace is good at special silica gel technology. Its food-grade products are mainly prepared by the precipitation method, focusing on the application of stabilizers in dairy products and nutritional supplements, and emphasizing low impurities and high dispersibility.

3.What are the characteristics of PQ's (now Huntsman's) food-grade silica gel?

PQ's food-grade products are positioned as "high-purity adsorbents". They enhance moisture absorption performance by optimizing the pore structure, and are widely used in foods that require long-term preservation such as dried fruits and crackers. They can also be used as spice carriers to extend the shelf life of flavor effects.

4.What is the business focus of PPG in the field of food-grade silica gel?

PPG has a relatively small output of food-grade silica gel, mainly focusing on the high-end beverage industry. It is used as a clarifying agent and suspending agent, which can effectively remove impurities in alcohol and prevent the precipitation of fruit pulp in fruit juice.

5.Who are the main players in the global food-grade silica gel market?

Leading enterprises include: Solvay (leading in scale after acquiring Rhodia), Evonik (a benchmark in vapor-phase technology), Grace (with advantages in special applications), and Huntsman (formerly PQ, outstanding in the adsorbent field), which together account for more than 60% of the global market share.

6.What are the specific application scenarios of Solvay's Tixosil® in the food industry?

It is mainly used in: ① Anti-caking agent for dry-mixed food (such as baking powder and seasonings); ② Stabilizer for liquid food (such as plant protein beverages); ③ Carrier for nutritional supplements to ensure the stability and uniform dispersion of vitamin proportions.

7.What is the name of Evonik's food-grade silica gel product series? Where is it applied?

Its core series are AEROSIL® (vapor-phase method) and SIPERNAT® (precipitation method). The former is used to improve the fluidity of high-end health products, and the latter is used as an anti-caking agent in dairy products, which can increase the dissolution rate of milk powder.

8.How to choose food-grade silica gel products from different enterprises?

It needs to be based on application scenarios: For anti-caking, prioritize Solvay's Tixosil® and Grace's products; for high-end stability requirements, choose Evonik's vapor-phase products; for adsorption and preservation, choose Huntsman (formerly PQ) products; for beverage clarification, choose PPG's special models.

V. Regulatory Standards Chapter

1.What mandatory standards does China have for food-grade silica gel?

Core standards include: ① GB 25576 "Food Additive - Silica Gel" (specifying purity, moisture ≤ 5%, ignition loss ≤ 8.5%); ② GB 2760 "National Food Safety Standard - Standards for the Use of Food Additives" (clarifying the scope of use and the principle of "appropriate use according to production needs").

2.What are the EU's regulatory requirements for food-grade silica gel?

Its code is E551, and the EFSA is responsible for safety assessment. Core requirements: crystalline content < 1%, heavy metal residues comply with Regulation (EU) 231/2012, and the scope of use covers most foods except baby food supplements.

3.How does the US FDA regulate the use of food-grade silica gel?

The FDA classifies it as a GRAS (Generally Recognized as Safe) substance with the code 21 CFR §172.480. It clearly stipulates that the addition amount shall not exceed 2% of the total mass of food, and it must be in an amorphous form.

4.Does the Codex Alimentarius Commission (CAC) have a unified standard?

Yes, it does. The CAC has developed general specifications for food-grade silica gel, including basic requirements such as purity, particle size (1-100μm), and heavy metal limits. Most national standards around the world are based on this as a reference framework.

5.What requirements must silica gel in imported and exported food meet?

It must meet the standards of both the exporting country and the importing country: For example, when Chinese food is exported to the EU, it must comply with both GB 25576 and Regulation (EU) 231/2012; when imported to the US, it must pass the FDA's GRAS certification and heavy metal testing.

6.Is food-grade silica gel allowed in organic food?

It is allowed in most countries. The organic standards of China, the EU, and the US all classify food-grade silica gel as an "acceptable food additive" because it is derived from natural silica and does not affect the core attributes of organic food.

VI. Application Scenarios Chapter

1.What is the main role of food-grade silica gel in dairy products?

Its core role is anti-caking and stabilization: Adding it to milk powder can prevent caking, improve fluidity, and ensure uniform dissolution; in cheese products, it can absorb excess moisture, extend the shelf life, and maintain a soft texture.

2.How is food-grade silica gel used in the beverage industry?

Its main uses include: ① A suspending agent in fruit juice to prevent pulp precipitation; ② A clarifying agent in beer and wine to remove impurities such as protein and improve transparency; ③ A stabilizer in plant beverages to prevent stratification.

3.What effect does adding silica gel have in baked food?

It can improve the fluidity of flour and prevent caking; in cake powder, it can enhance the stability of the batter and reduce volume shrinkage during baking; in biscuits, it can absorb excess moisture and maintain a crispy texture.

4.Why is food-grade silica gel added to condiments?

It is used as an anti-caking agent and carrier: Adding it to chicken essence, monosodium glutamate, and powdered sugar can prevent moisture absorption and caking, ensuring smooth pouring; when used as a spice carrier, it can absorb volatile flavor substances and extend the shelf life of flavor effects.

5.What is the role of silica gel in nutritional supplements?

First, it is used as an anti-caking agent to prevent vitamin and mineral powders from caking; second, it is used as a dispersant to ensure the uniform distribution of active ingredients and ensure the consistency of the content of each supplement; third, it improves the disintegration of tablets or capsules.

6.What is the application of silica gel in frozen food?

In quick-frozen products such as dumplings and glutinous rice balls, it can form a protective film on the surface of the ingredients, prevent the formation of excessive ice crystals during freezing from damaging the texture, and reduce water loss after thawing to maintain a fresh taste.

7.How is food-grade silica gel used in food packaging?

As a micro-moisture absorbent in packaging, it can absorb excess moisture and oxygen in the packaging, prevent food oxidation and mildew, and extend the shelf life. It is commonly used in the sealed packaging of nuts and baked food.

8.Besides food, in which other fields can food-grade silica gel be used?

It can be used in pharmaceuticals (as a tablet disintegrant), oral care products (such as a mild polishing agent in children's toothpaste, e.g., Solvay's Tixosil Soft Clean™), cosmetics (as an oil absorbent and thickener), and other fields.

VII. Testing and Compliance Chapter

1.How to test the content of silica gel in food?

The mainstream methods are inductively coupled plasma atomic emission spectrometry (ICP-OES) or X-ray fluorescence spectrometry (XRF). The total amount of silica gel is calculated by measuring the content of silicon, with a detection sensitivity of up to 0.1mg/kg.

2.How to identify the authenticity of food-grade silica gel?

Core testing items include: ① X-ray diffraction (XRD) to identify the crystal structure (food-grade should be amorphous); ② Heavy metal testing (atomic absorption spectrometry); ③ Specific surface area determination (BET method) to ensure compliance with product specifications.

3.What compliance requirements must food enterprises abide by when using silica gel?

They need to: ① Use food-grade products that meet national standards; ② Strictly control the addition amount, not exceeding the provisions of GB 2760; ③ Label "silica gel" or "E551" on product labels as required; ④ Keep the qualifications of suppliers and product testing reports.

4.How can consumers check whether food contains silica gel?

They can directly check the "ingredient list" on the food packaging. If it contains "silica gel", "silica", or "E551" (common in imported food), it means that this ingredient has been added.

VIII. Market and Trend Chapter

1.What is the size of the global food-grade silica gel market?

In 2024, the global market size has exceeded 2 billion US dollars. The Asia-Pacific region has become the largest market due to the rapid development of the food industry. It is expected to grow at an annual rate of 5%-7% from 2025 to 2030.

2.What are the factors driving the growth of demand for food-grade silica gel?

They mainly include: ① The popularity of convenience food and prepared food (requiring anti-caking and preservation); ② The rapid development of the nutritional supplement industry; ③ The increasing global demand for extending food shelf life; ④ The expansion of application scenarios brought about by the upgrading of production processes.

3.What is the technical development trend of food-grade silica gel?

The core trends are "high-endization" and "environmental protection": ① Developing nano-scale products with smaller particle sizes for precise stabilization; ② Optimizing the vapor-phase process to reduce energy consumption; ③ Developing biodegradable composite silicon-based materials to improve environmental performance.

4.What are the differences in demand for food-grade silica gel in different regions?

The Asia-Pacific region focuses on basic anti-caking needs (such as milk powder and condiments); Europe and the US focus on high-end applications (such as organic food stabilizers and health product carriers); the demand growth in emerging markets mainly comes from the baking and quick-frozen food fields.

5.Will food-grade silica gel be replaced in the future?

It is difficult to be completely replaced in the short term. It has multiple functions such as anti-caking, stabilization, and adsorption, with low cost and high safety. Although there are other anti-caking agents (such as tricalcium phosphate), their comprehensive performance and application scenarios are not as good as those of silica gel. In the future, they will be more complementary rather than substitutive.

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