The application of precipitated silica in the milk powder and flavoring industries primarily involves its dual functions as an anti-caking agent and an adsorbent carrier. Its use strictly adheres to Chinese and international food safety standards, and the technical approach varies depending on the material type and process requirements.

I. Anti-Caking Function in the Milk Powder Industry
Regulatory Basis: According to GB 2760-2024 National Food Safety Standard - Standards for the Use of Food Additives, precipitated silica is permitted as an anti-caking agent in regular milk powder (not infant formula), with no specific maximum usage limit, but it must meet purity requirements (SiO₂ content ≥90%, heavy metal limits met).
Mechanism of Action: Its nano-scale porous structure (specific surface area 50–300 m²/g) physically adsorbs moisture and disrupts inter-particle forces, breaking down capillary forces and van der Waals forces between powder particles, significantly improving fluidity and preventing caking and clumping, ensuring uniform dissolution.
Scope of Application: Suitable for whole milk powder, skim milk powder, modified milk powder, and other powdered dairy products.  **Strictly prohibited for use in infant formula for infants aged 0-6 months**, as this type of food prohibits the addition of any non-nutritive additives (including flavorings, thickeners, etc.).
Material Selection: Precipitated silica is commonly used in the industry due to its low cost, strong adsorption capacity, and compliance with food-grade purity requirements, meeting the needs of large-scale production.

II. Carrier Function in the Flavoring Industry
Technical Principle: As an adsorbent carrier, precipitated silica physically adsorbs liquid flavoring molecules through its high specific surface area (up to 700 m²/g), forming a stable, free-flowing powdered flavoring (precursor to microencapsulation), achieving solidification, sustained release, and anti-volatilization of the flavoring. Preparation Methods:
Precipitation Method: Silica gel is produced by neutralizing water glass with acid. After drying and grinding, a highly adsorbent powder is obtained, suitable for use as a carrier for conventional food flavors (such as milk and fruit flavors).
Gas Phase Method: Produced by high-temperature hydrolysis of SiCl₄, with a purity >99% and smaller particle size (5–40 nm), suitable for high-end, high-stability flavor systems, such as baking and dairy flavoring products, but at a higher cost.
Compliance: As an auxiliary material for food flavors, precipitated silica is an allowed carrier substance under the "Food Additive Licensing Review Rules 2025 Edition". Its use must comply with flavor production licensing regulations, but it is not considered a flavor itself.

III. Compliance of Dual Function in Flavored Milk Powder
Simultaneous Use Allowed: In ordinary flavored milk powder (non-infant formula), precipitated silica can be used simultaneously as an anti-caking agent and a flavor carrier, because its function is physically assistive and not a flavor component, thus not violating the definition of "scope of use of food additives" in GB 2760.
Key Distinction:
Flavor: An additive used to impart flavor; prohibited in infant formula.
Precipitated Silica: An additive used to improve physical properties; permitted in non-infant formula.
Practical Application: In flavored milk powder containing vanillin, vanilla extract, etc., precipitated silica can simultaneously achieve the dual objectives of "stabilizing flavor distribution" and "preventing caking," improving product quality and shelf stability. IV. Comparison of Fumed Silica and Precipitated Silica Performance
Characteristic | Fumed Silica | Precipitated Silica
Purity | >99% | ~93%
Particle Size | Nanometer scale (5–40 nm) | Micrometer scale (1–10 μm)
Specific Surface Area | 100–400 m²/g | 150–700 m²/g
Silanol Content | 2–3 SiOH/nm² | ~6 SiOH/nm²
Hygroscopicity | Low | High
Main Advantages | High dispersibility, high thixotropy, excellent thermal stability | High adsorption capacity, low cost, easy processing
Application in Milk Powder | Used in small quantities in high-end functional milk powder | Mainstream choice, widely used in ordinary milk powder
Application in Flavors | High-end, high-stability flavor carrier | Mainstream adsorption carrier, suitable for over 90% of food flavors

V. International Standards and Safety
China: GB 2760-2024 and GB 1886.96-2024 clearly define its use as a food additive.
International:
FDA: Listed as GRAS (Generally Recognized as Safe), allowed for use as needed, with no ADI limit.
EFSA: Assessment confirms its safety for use in food, with no daily intake limit.
Codex Alimentarius: Although not separately listed for limits of silica in milk powder/flavors, its framework is consistent with GB 2760, supporting its legal use as food-grade silicon dioxide.
VI. Technical Support and Empirical Research
Anti-caking Mechanism: The "high-temperature ashing-hydrofluoric acid dissolution-constant weight method" established by Chinese patent CN102875571A can accurately determine the silica content in milk powder (detection limit 0.4 g/kg), verifying its actual presence and distribution in the product.
Adsorption Kinetics: Studies show that the silanol groups (SiOH) on the surface of silicon dioxide can form hydrogen bonds with flavor molecules (such as alcohols and ketones), achieving stable adsorption with a fast adsorption rate and short equilibrium time. Industrial validation: Precipitated silica has been widely used in powdered food products such as instant coffee, cocoa powder, and non-dairy creamer. The technology is mature, and its safety has been verified over several decades.