50 Essential Q&As on Food-Grade Adsorbent Silica for Animal/Plant Oils and Beer Applications

I. Basic cognition and core characteristics

1.What is the food grade adsorbent silica used for animal and vegetable oils?

This amorphous silica powder, specifically designed for oil refining, is prepared through precipitation or gas-phase methods. It features precisely controlled pore size distribution (typically 2-50nm) and high specific surface area (150-200m²/g). The material selectively adsorbs pigments, heavy metals, plasticizers, and oxidation products in oils, while complying with food additive standards such as GB 25576-2020. With a purity of ≥99.5%, it ensures optimal performance in industrial applications.

2.What are the special properties of silica used as food grade adsorbent in beer industry?

This silica, known as beer stabilizer, exists in two forms: hydrogel and xerogel. Its core feature is selective adsorption—binding only haze-active proteins (key components causing turbidity through polyphenol reactions) with molecular weights above 40,000 kDa, while leaving 10,000-20,000kDa hydrophobic proteins essential for beer foam stability unaffected.

3.What is the difference between silica, an adsorbent used in oil and beer, and ordinary food-grade silica?

The core difference lies in adsorption targeting: oil-based products focus on pore size matching pigments/heavy metal molecules, with hydrophilic surface modification to enhance adsorption of polar impurities; beer-based products optimize surface charge to specifically recognize hydrophilic turbid proteins, while ordinary food-grade silica only focuses on anti-agglutination and fluidity improvement.

4.What are the key indicators to measure the performance of silica adsorbent for oil?

The key parameters are: ① Specific surface area (optimal range: 150-200 m²/g); ② Pore size distribution (2-10nm for chlorophyll, 10-30nm for heavy metals); ③ Burn reduction (≤5%, indicating purity); ④ Decolorization capacity (≥100 mg/g, measuring pigment removal efficiency).

5.Why is the "moisture content" index of silica adsorbent important for beer?

Direct impact on usage characteristics: Hydrogel containing 60%-70% water requires longer stirring time for dispersion but is low cost; dry gel containing only 5% water is easy to disperse but produces a lot of dust, may reduce the filtration flow rate, and is difficult to dissolve in alkaline solution, affecting filter regeneration.

6.Can food grade adsorbent silica treat all types of animal and vegetable oils?

It can process most categories, including soybean oil, rapeseed oil, olive oil, lard, etc., but targeted selection is required: high acid value oils (such as rice bran oil) need high specific surface area models to enhance acid price control; cold pressed oils (such as extra virgin olive oil) need low adsorption strength models to avoid the loss of flavor substances.

7.What is the difference between the demand for silica adsorbent in craft beer and industrial beer?

Craft beer emphasizes 'flavor retention,' requiring low-dose, highly selective formulations (such as dry gels) to prevent adsorption of hop aroma components. Industrial beer focuses on 'large-scale stability,' utilizing cost-effective hydrogels with continuous filtration processes to enhance efficiency, while complying with regulations like Germany's' Pure Brewing Method.'

8.What impurities can be removed by silica adsorbent in oil besides decolorization?

In addition to pigments (chlorophyll, carotenoids), it can also remove:

① heavy metals (lead, arsenic, etc., through dual effects of ion exchange and adsorption);

② plasticizers (such as DEHP, using microporous retention);

③ oxidation products (aldehydes, ketones, delaying oil rancidity);

④ phospholipids (improving oil transparency).

9.Does the use of adsorbent silica in beer affect the foam and taste?

It has no adverse effects. The system selectively adsorbs hydrophilic macromolecular proteins (≥40,000kDa) associated with turbidity, while leaving hydrophobic proteins (10,000-20,000kDa) that maintain foam stability unaffected. Moreover, it completely removes these proteins during filtration without leaving residual odors or altering the wine's taste.

10.Is the amorphous structure of food-grade silica adsorbent critical for application?

Yes, and this is a regulatory requirement. Crystalline silica may pose health risks, whereas amorphous silica is not only safe (certified by FDA and EFSA), but its porous network structure also provides efficient adsorption channels. The crystalline content must be strictly controlled below 1% to ensure both adsorption performance and safety.

II. Application of animal and vegetable oils: mechanism and effect

11.How does silica adsorbent play a role in the decolorization of animal and vegetable oils?

The material's abundant microporous structure (specific surface area 150-200m²/g) provides numerous adsorption sites for binding pigment molecules (e.g., chlorophyll) via van der Waals forces. Concurrently, surface hydroxyl groups form hydrogen bonds with polar impurities, enabling targeted capture. This process achieves decolorization rates of 80%-95% without disrupting the triglyceride structure of oils.

12.Why can silica adsorbent prolong the shelf life of animal and vegetable oil?

The core mechanism is achieved through "dual protection": ① Adsorbing trace metal ions (such as iron and copper) in oils that cause oxidation, thereby breaking the oxidation catalytic chain; ② Capturing initial oxidation products (such as hydrogen peroxide), preventing their further decomposition into harmful aldehydes and ketones, which can extend the oil's shelf life by 30%-50%.

13.What is the difference in the effect of silica dioxide prepared by different processes in oil adsorption?

The gas-phase method yields products with high purity (≥99.8%) and uniform pore size, ideal for precision decolorization of premium oils like olive oil, while preserving more flavor compounds. The precipitation method, on the other hand, offers lower costs and adjustable specific surface area (100-200m²/g), making it more cost-effective for bulk oil purification such as soybean oil.

14.Can silica adsorb plasticizer pollution in animal and vegetable oils?

This method is feasible. The pore size can be adjusted to match the molecular dimensions of common plasticizers (e.g., DEHP, DBP) (5-20nm), achieving removal rates of 70%-90% through micropore retention and surface adsorption. When combined with activated carbon, the plasticizer content can be reduced to below 0.1mg/kg, meeting national standards.

15.How to determine the amount of silica adsorbent in oil refining?

Adjustments should be made based on oil type and impurity content: 

① For crude oil decolorization: typically add 0.2%-1.0% of oil weight; 

② For high-impurity oils (e.g., gutter oil refining): increase to 1.5%-2.0%; 

③ For refined oil polishing: only 0.05%-0.1% is required. Excessive addition will increase costs and filtration burden, so the optimal dosage should be determined through pilot testing.

16.Does temperature affect the effect of silica adsorbent on oil treatment?

The optimal temperature range is 60-80℃. Below 60℃, the oil's high viscosity slows impurity diffusion and reduces adsorption efficiency. Above 80℃, excessive molecular thermal motion weakens adsorption, causing impurities to desorb. To ensure complete adsorption, stir for 15-30 minutes within this temperature range.

17.Will the nutrients be lost after the oil is treated with silica adsorbent?

With minimal loss, this material demonstrates strong chemical inertness, specifically adsorbing impurities like pigments and heavy metals while showing no affinity for nutrients such as vitamin E and essential fatty acids in oils. Experimental results indicate a vitamin E retention rate of ≥95% post-treatment, with no significant changes in fatty acid composition, outperforming traditional adsorbents like activated white clay.

18.Why is silica adsorbent particularly suitable for the refining of cold pressed vegetable oil?

Cold-pressed oils require avoiding high-temperature processing to preserve active components, while silica can effectively remove impurities at room temperature: 

① Low-temperature adsorption preserves nutrients like polyphenols and sterols; 

② Gentle decolorization without trans fatty acids; 

③ Ultra-low residue (≤10mg/kg), eliminating complex post-processing and aligning with the natural essence of cold-pressed oils.

19.Can silica adsorbent replace alkali refining process in animal and vegetable oil deacidification?

While not fully substitutable, it can assist in optimization. Its adsorption capacity for free fatty acids is relatively weak (removal rate ≤30%), but it can adsorb soap foot impurities generated during alkali refining, reducing the number of washes. In low-acid-value oils (acid value ≤2 mg KOH/g), it can partially replace alkali refining, thereby reducing oil loss and wastewater discharge.

20.How to determine that the adsorbent silica has reached adsorption saturation?

Three key indicators can be used to determine this: 

① The oil's light transmittance stabilizes above 95% with no further increase; 

② The oil's acid value and peroxide value remain stable after filtration; 

③ The adsorbent's color changes from white to yellowish-brown (indicating pigment adsorption saturation). The saturated adsorbent should be promptly separated to prevent impurities from re-dissolving.

Beer applications: clarification and stabilization mechanisms

21.How does silica adsorbent solve the problem of "cold turbidity" in beer?

Beer haze is formed through the reaction of haze-active proteins (molecular weight over 40,000 kDa) with polyphenols. The microporous structure of silica can specifically adsorb these proteins, thereby interrupting the reaction chain. Even at low temperatures of 0-4℃, the beer remains clear, with no significant haze precipitation observed after storage for over 6 months.

22.How is the "selective adsorption" of silica as an adsorbent in beer achieved?

Through process control, its surface exhibits a specific charge distribution that binds exclusively to hydrophilic haze-active proteins via electrostatic attraction and hydrogen bonding, while remaining unaffiliated with the hydrophobic proteins (10,000-20,000kDa) responsible for foam retention, achieving the precise effect of 'removing turbidity without compromising foam integrity'.

23.What are the differences between hydrogels and xerogels in beer applications?

Core differences in processing characteristics: 

① Hydrogel (60%-70% water content): low cost, requires 10-15 minutes of stirring to disperse, suitable for mass production;

② Dry gel (5% water content): fast dispersion (1-2 minutes), but high dust, may reduce the filtration flow rate, and difficult to dissolve in alkali solution, affecting filter regeneration.

24.What are the timing and methods of adding silica dioxide in beer?

The optimal timing is 5-10 minutes prior to filtration, when the beer has completed fermentation and impurities are concentrated but not yet filtered. The additive should first be mixed with 5-10 times the amount of deoxygenated water for dispersion, then slowly injected into the beer while maintaining a stirring speed of 50-100rpm to prevent excessive foaming that may affect the taste.

25.Does the use of silica, an adsorbent, in craft beer, affect the aroma of hops?

Proper application prevents this. Select a low-adhesion dry gel formulation with a dosage ≤50g/hL. Its pore size is optimized for proteins (above 40,000kDa), while smaller components like terpenes in hop aroma remain unretained, preserving the unique flavor profile of craft beer.

26.Can silica, an adsorbent, improve the filtration efficiency of beer?

Yes. While adsorbing proteins, it can form a loose filter cake layer to reduce filtration resistance. Experiments show that adding 50g/hL silica can increase filtration speed by 20%-30%, and the filter cake is easy to peel off, prolonging the service life of the filter membrane, which is especially suitable for the filtration of high viscosity wheat beer.

27.What is the relationship between the addition of silica in beer and the clarification effect?

The relationship follows a 'first increase, then stabilization' pattern: When the dosage rises from 0 to 30g/hL, clarity improves rapidly (transparency increases from 70% to 98%); beyond 50g/hL, no significant improvement is observed, and it may even cause filter membrane clogging or residue risks. The standard dosage for industrial beer is 30-50g/hL, while craft beer can be reduced to 10-30g/hL.

28.Why is silica adsorbent almost no residue in beer?

As it is insoluble in beer and the particle size (1-5μm) is larger than the pore size of the filter membrane (usually 0.45μm), it can be completely retained in the subsequent plate and frame filtration or diatomite filtration. The test shows that the residual silica in the filtered beer is less than or equal to 1mg/L, far below the regulatory limit, and the safety is very high.

29.Can silica adsorbent replace PVPP (cross-linked polyvinylpyrrolidone) in beer?

It can be partially substituted or combined with other additives. While silica excels at removing proteins, PVPP is specialized in eliminating polyphenols. Using silica alone resolves 80% of turbidity issues, whereas combined use achieves over 95% stability with reduced PVPP consumption (cutting costs by 30%), making it particularly suitable for dark beers with high polyphenol content.

30.Does using silica adsorbent affect the performance of high-alcohol beer (≥10% ABV)?

The impact is relatively small. High alcohol content will slightly reduce the solubility of protein, but the adsorption force of silica (electrostatic attraction + hydrogen bond) is not affected by alcohol; only by increasing the addition amount by 10%-20% and extending the contact time to 15 minutes, the same clarification and stability effect as ordinary beer can be achieved.

IV. Process Application and Practical Optimization

31.In the refining of animal and vegetable oils, how should the adsorbent silica be combined with other adsorbents?

Common blending formulations: 

① Decolorization blend: Silica (0.5%) + Activated clay (1.0%). Silica adsorbs heavy metals to reduce clay consumption, achieving a 15% decolorization rate increase. 

② Deep purification: Silica (0.3%) + Activated carbon (0.1%). Activated carbon eliminates odors while silica removes pigments, ideal for premium oil refining.

32.In beer production, is there a particular order of use of adsorbent silica and diatomite?

The 'adsorb first, then filter' principle must be followed: add silica to adsorb proteins (contact for 5-10 minutes) before adding diatomite as a filter aid. This creates an 'adsorption-filtering' synergistic system. If the order is reversed, diatomite will occupy the filtration channel first, preventing silica from adequately contacting proteins, resulting in a 50% reduction in efficiency.

33.What is the effect of pH on the adsorption of silica dioxide on oil?

The optimal pH range is 6.0-7.5: ① When pH <6.0, surface hydroxyl groups become protonated, reducing adsorption capacity for polar impurities; ② When pH> 8.0, silica may partially dissolve to form sodium silicate, compromising oil flavor and safety. The pH should be adjusted to the optimal range using citric acid or sodium hydroxide.

34.How to avoid "filter membrane blockage" when adding adsorbent silica to beer?

Three key points:

① Particle size control: Select models with 1-5 μm particle size to avoid ultrafine particles (<1 μm); 

② Full dispersion: Ensure uniform mixing with water without agglomeration; 

③ Concentration control: The dosage should not exceed 50g/hL, and 0.1% diatomite can be added as a filter aid to loosen the filter cake structure.

35.How to control the stirring speed of silica adsorbent in the refining of animal and vegetable oil?

The stirring speed should be adjusted according to the process stage: 

① Mixing stage (initial addition): 150-200rpm to ensure rapid dispersion; 

② Adsorption stage: 50-100rpm to avoid excessive shear that damages the oil structure; 

③ Standing stage: Stop stirring to allow the adsorbent to settle naturally, reducing subsequent filtration pressure.

36.Is there a difference in the demand for silica adsorbent for different types of malt beer?

Significant differences:

① Barley malt beer: low protein content, requiring 30g/hL; 

② Wheat malt beer: high haze-active protein content, requiring 50g/hL; 

③ Roasted malt beer: high polyphenol content, recommended to use silica (40g/hL) + PVPP (20g/hL) for simultaneous protein and polyphenol removal.

37.Does silica dioxide, an adsorbent, play a supporting role in the deodorization process of oil?

It provides indirect auxiliary effects. Adding 0.1%-0.2% silica before deodorization can adsorb heat-sensitive impurities (such as polymers) generated during the deodorization process, reducing the deposition of these impurities in the deodorization tower. At the same time, it adsorbs trace metal ions to prevent further oxidation of grease during deodorization, thereby improving the deodorization efficiency.

38.Is it possible that the beer is still cloudy after filtration due to improper use of silica?

Common causes: 

① Late addition timing (within 1 minute before filtration), resulting in insufficient adsorption; 

② Incomplete dispersion causes silica agglomeration and reduced effective adsorption sites; 

③ Incorrect model selection (using hydrogel for high-protein beer) leads to inadequate adsorption capacity. Targeted adjustments to process parameters are required.

39.How to improve the separation efficiency of oil treated by adsorbent silica during filtration?

The "three-stage filtration" system can be implemented: 

① Primary filtration (10μm filter bag) to remove large adsorbent particles;

② Fine filtration (1μm filter membrane) to eliminate fine particles; 

③ Polishing filtration (0.45μm filter membrane) to ensure residual amount ≤10mg/kg. The filtration temperature is maintained at 60-70℃ to reduce oil viscosity and enhance flow rate.

40.How to recycle used silica adsorbent in beer production?

Due to the adsorption of organic substances such as protein, direct recovery is difficult. At present, the mainstream treatment methods are: 

① As a biomass fuel additive (the adsorbed organic matter can be assisted in combustion); 

② Regenerated by high temperature incineration (above 800℃), after removing the adsorbed impurities, it can be used for industrial purposes (such as building materials), in line with environmental protection requirements.

V. Safety, Regulations and Compliance

41.Are there regulatory limits on the amount of food-grade adsorbent silica left in oils and beers?

There are clear standards:

① China GB 2760-2024 stipulates that the residual amount in oils is ≤10mg/kg, while beer has no mandatory limit (as there is almost no residue after filtration);

② The EU E551 standard requires that the total residual amount in food is ≤30mg/kg;

③ The US FDA lists it as a GRAS substance, allowing "moderate use as needed for production".

42.Is it a health risk to eat oils and beer that contain trace amounts of silica for a long time?

It is risk-free. Chemically stable, it is not digested or absorbed by the human body and is completely excreted with feces, with no accumulation in the body. The EFSA's 2024 assessment confirmed that even a daily intake of 30mg (far exceeding normal dietary exposure) poses no safety risks to adults or infants, with no reported cases of allergies.

43.What are the special requirements for silica for organic certified oils and beers?

It must meet the standards for organic food additives:

① Raw materials must be sourced from natural silica (not synthetic chemicals);

② The production process must be free of genetically modified components and chemical solvent residues;

③ It must obtain organic certification from either the EU ECOCERT or the USDA, with the addition amount reduced by more than 20% compared to conventional food to ensure organic attributes.

44.What are the regulations that the export beer using adsorbent silica should comply with in the importing country?

Targeted compliance requirements:

① For EU export: Comply with EU Regulation 231/2012, with crystalline content <1% and lead content ≤1mg/kg;

② For US export: Obtain FDA GRAS certification and provide production process and safety reports;

③ For Japan export: Meet the Ministry of Health, Labour and Welfare's' List of Food Additives' with residue levels ≤5mg/L.

45.What compliance documents should be retained by food enterprises using adsorbent silica?

The core documents include: ① Supplier's production license and product qualification certificate; ② Third-party test reports (covering purity, heavy metals, and crystalline content); ③ Batch usage records (addition amount, time, and effect); ④ For imported products, additional customs declaration form and entry inspection and quarantine certificate are required.

VI. Competitor Comparison and Selection

46.What are the advantages of silica adsorbent in oil decolorization compared with activated clay?

Key advantages:

① Gentle decolorization with 15%-20% vitamin E retention;

② No oil adsorption (active clay adsorbs 15%-20%, silica <5%), minimizing waste;

③ Low residue (≤10mg/kg vs. white clay ≤50mg/kg);

④ Reduced wastewater discharge (white clay requires multiple washes, silica only one).

47.What are the technical advantages of using silica as a sorbent instead of gelatin in beer?

Key advantages:

① Eliminates low-temperature processing (gelatin requires 0-4℃, silica can be stored at room temperature), reducing energy consumption;

② Free from animal-derived risks, suitable for vegetarians and halal certification;

③ Acts faster (5 minutes vs. 2 hours for gelatin), shortening production cycles;

④ Maintains beer's pH balance with enhanced stability.

48.How to choose the appropriate adsorbent silica for different oil categories?

Selection Guidelines: ① Soybean oil/Cottonseed oil (high pigment): Choose models with high specific surface area (200m²/g) using precipitation method; ② Olive oil/Tea seed oil (high flavor): Select high-purity models via gas-phase method; ③ Animal fat (high cholesterol): Opt for models with large pore size (30-50nm) to adsorb cholesterol precursors; ④ Hydrogenated vegetable oil (high stability required): Choose hydrophobic modified models.

49.What product parameters should beer enterprises pay attention to when choosing silica?

Core parameters:

① Protein adsorption capacity (≥80mg/g is optimal);

② Particle size distribution (1-5μm, avoiding particles <1μm);

③ Moisture content (60%-70% for hydrogel, <10% for dry gel);

④ Dispersion (no agglomeration after 3 minutes of water mixing);

⑤ Filtration compatibility (no clogging of 0.45μm filter membrane).

50.What are the technical upgrade directions of silica adsorbent for oil and beer in the future?

The core trends include:

① Functional modification: Developing antibacterial silica that simultaneously adsorbs and preserves freshness;

② Precision control: Optimizing pore size and surface charge to design products targeting specific impurities (such as certain plasticizers and proteins);

③ Green production: Adopting low-energy precipitation processes to reduce carbon emissions by over 25%, aligning with sustainable development requirements.