The food industry knows silicon dioxide (EU) (SiO2) as a stable, tasteless, anti-caking white powder. In fact, it is a ‘dry’ topic – pun intended. However, silicon dioxide can be a great tool for developers when processing powdered foods, and may be a key link for bone health in the future.
Silica Basics
Silica (EU), or silicon dioxide, as a crystalline structure, is found abundantly in the crust of the earth. In water, silica becomes the highly bioavailable orthosilicic acid (EU). Amorphous (non-crystalline) forms of silicon dioxide are found in nature as biogenic silica from volcanos, and within plants like cereal grains and vegetables. However, with two main processes, silicon dioxide, both natural and synthetic, can be made amorphous and optimized for specific applications.
- Thermal process (vapor phase hydrolysis): Produces fumed (EU)(pyrogenic) silicon dioxide.
- Wet process: Produces precipitated (EU) silicon dioxide or solid silica gel (EU).
Synthetic amorphous silica (SAS) is normally more pure then natural silicon dioxides. Changing processing parameters, like pH or temperature, can yield silicon dioxide powders with improved flowability or absorption levels tailored to specific end uses.
Regulatory Considerations:
In the US, the FDA regulates Silicon dioxide use under 21 CFR 172.480. The CFR specifically references silicon dioxide from the vapor phase hydrolysis process, or fumed silicon dioxide, but all forms of silicon dioxide have a FDA GRAS notification established.
Approved Direct Uses:
- For anti-caking at the lowest usage level to achieve anti-caking in foods where it is demonstrated up to 2% by weight of the food.
- In beer manufacturing as a stabilizer that prevents chill haze during production and is filtered out of the end product.
- In tableted foods for special diets as an absorbent for dl-a- tocopheryl acetate and pantothenyl alcohol.
- In flavor microencapsulation (21 CFR 172.230), and in powdered eggs (21 CFR 160.105 and 160.185).
Silicon dioxide is approved as a defoaming agent (21 CFR 173.340), and indirectly in processing equipment as a coating or as grease/lubricants. Use is permitted in packaging adhesives, paper and paperboard and polymers, as well as in the ink used on fruits and vegetables (21CFR 175, 176, 177, 178 and 73.1).
The EU regulates silicon dioxide use under E 551-559. For anti-caking, maximum limits are allowed up to 1%. However, a wide range of levels are permitted in various food categories and in tablets. This includes up to quantum satis, meaning a maximum level is not specified under GMP conditions if the consumer is not misled and the ingredient is used at the lowest level to achieve the intended purpose.
Silicon Dioxide Nutrition
Silicon dioxide, or silica, is considered a trace mineral and hypothesized to enable mineralization for bones, teeth, and collagen. Silicon dioxide has not been widely studied, so a daily required intake level is not established. However, initial research reported in the last year regarding osteoporosis indicates that the future for bone health may be silicon dioxide. The additive silicon dioxide is less bio-available than sources found in grains, plants or aqueous forms, but with concerns about bone health in an aging population, silicon dioxide will continue to be researched.
Formulating Powdered Foods
Silicon dioxide is widely used as a food additive in powdered or granulated products for many reasons:
- Enables developers to create powders which flow in processing equipment at higher speeds. Ant-caking is important in humid climates or with extremely hydroscopic ingredients like tomato powder.
- Creates dry blends that remain free flowing during tote storage before final packaging.
- Allows quick dispersion of dry ingredients in liquids by keeping the dry ingredients from clumping.
- Encapsulates volatile liquid flavors for dry applications.
- Prevents sticking in spray dryers to achieve better efficiencies.
Formula Considerations:
- As usage rates change for specific applications in the EU, and to some extent in the US, check local regulations to ensure end product compliance.
- Work with vendors to establish minimum purity of the ingredient and maximum levels of contaminants, especially hard metals.
- Raw material silicon dioxide should be kept in dry storage to prevent moisture absorption before processing.
- Care should be taken to minimize dusting within the processing line.
- Consumers may notice undissolved particulates in end food products because silicon dioxide has low to no solubility in water.
- As silicon dioxide has a chemical sounding name on ingredient lines and a ‘sand’ origin, mainstream consumer information may change consumer perception. Potential alternatives, like processed rice hulls (EU), , which contain natural silica, may function in applications as a replacement for silicon dioxide.
Product Resources
North America
AEROSIL® 200 F by Evonik Industries AG Silica
Zeofree® 80 by Barrington Nutritionals
TIXOSIL® 38A by Rhodia Silica Systems
SYLOID® 244 FP by GRACE
Europe
AEROSIL® 200 F by Evonik Industries AG Silica
PERKASIL® SM 500 F by GRACE
HDK® N20 NUTRITION by Wacker Chemie AG
KiGel® by Erbslöh Geisenheim AG
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I was under the impression that silicon dioxide was not a bioavailable form of silicon and that regulatory bodies only recognized forms silicon forms such as silicic acid and Silica HVP chelates as bioavailable.
Thanks for your comment Jeremy!
In terms of regulatory recognition, EFSA recognized in their report that:
“No data have been submitted on the bioavailability of silicon from either silicon dioxide or silicic acid gel. However, several studies have shown that silicon present under similar form was readily available from foods and in many cases showed absorption similar to that of silicon from liquids. Furthermore, given the conversion of silicon dioxide/silicic acid to orthosilicic acid upon hydration, and the bioavailability of silicon from orthosilicic acid, the Panel considers that silicon from silicon dioxide/ silicic acid gel is bioavailable.”
I hope this information helps!
Jill Frank
My colleagues required a form last year and saw a company with 6 million forms . If people are wanting it too , here’s
http://goo.gl/IyBXlDThere is a lot of SiO2 produced as a byproduct during the production of AlF3. (2Al(OH)3+H2SiF6=2AlF3+SiO2+4H2O). For what purposes can this silicone dioxide be used?
Dear Jill. I work in animal nutrition and interested in the potencial use of Silicom coming from Orykta product ( SiO2 at 52 % ).. At present, this product is recomended mainly for soil-plant nutrition, Scientifics articles show a strong differences in bioavalability among silicom sources. In general, the information about silicom for animals use is scarse. Do you have some information about silicom dioxide bioavailability.
Thanking you in advance for your courtesy