DIMETHYL POLYSILOXANE 

Introduction

Dimethyl polysiloxane (E900), often simply called dimethicone or silicone, is a synthetic polymer. Its primary function as a food additive is as an antifoaming agent (anti-foaming agent). It prevents the formation of foam during the production, packaging, and preparation of various foods. This is crucial for efficiency, safety (preventing boil-overs), and product quality.

Its effectiveness comes from its very low surface tension. It spreads rapidly over the surface of a liquid, breaking down existing bubbles and preventing new ones from forming. Despite being a synthetic chemical, EFSA has concluded that there is no safety concern at the reported uses and use levels.

CAS Number

63148-62-9

Synonyms

Dimethicone; E900; PDMS; Silicone oil.

Topic Headings

1. Mechanism of defoaming: surface chemistry in action (list form)

• Low Surface Tension: Dimethyl polysiloxane has an extremely low surface tension (approximately 20 dyn/cm), which is much lower than water (72 dyn/cm) or oils.
• Rapid Spreading: A tiny drop of E900 will instantly spread across the surface of a liquid, displacing water or oil molecules.
• Bubble Wall Disruption: The foam bubbles are stabilized by a thin film of liquid. When E900 contacts this film, it migrates to the air-liquid interface, creating a weak spot that causes the bubble to collapse.
• Insolubility: It is practically insoluble in water, food acids, and most oils. This ensures it remains at the surface to do its job and is not dissolved away.
• High Stability: It is not affected by heat, pH changes, or most food chemicals, so it remains active throughout processing.

2. Physical and chemical properties (list form)

• Appearance: Clear, colorless, viscous liquid.
• Odor: Odorless.
• Taste: Tasteless.
• Solubility: Insoluble in water and most polar solvents; soluble in hydrocarbons and some organic solvents.
• Viscosity: Available in a wide range of viscosities (from runny to thick paste).
• Stability: Chemically inert, non-toxic, and non-flammable. It is extremely stable to heat and oxidation.
• Density: Approximately 0.96-0.97 g/mL.

3. Food applications and typical usage levels (list form)

• Deep-frying oils (industrial) – Added at 1-10 ppm to prevent foaming and extend oil life.
• Canned vegetables and fruit – Prevents foaming during the filling and seaming process.
• Jam, jelly, and marmalade production – Used to control foam during high-speed boiling and filling.
• Soft drinks and juices – Prevents foam during the bottling and canning of carbonated and non-carbonated beverages.
• Wine and liquor production – Used as a processing aid to control foaming during fermentation and bottling.
• Chewing gum base – Acts as a softening and lubricating agent in the base itself.

4. Regulatory status and safety (paragraph form)

Dimethyl polysiloxane (E900) is a permitted food additive in the EU, with specific maximum usage levels set for different food categories. It has been re-evaluated by EFSA, which concluded that its use at the reported levels does not pose a safety concern. Because it is a very large, inert polymer, it is not absorbed from the gastrointestinal tract in any significant amount. It passes through the body unchanged and is excreted in the feces. There have been unsubstantiated and often misleading health claims in popular media linking E900 to various disorders. However, scientific consensus and EFSA's rigorous re-evaluation confirm its safety at the low levels used in food.