E555 (Potassium aluminium silicate) is a chemical compound extracted from natural sources and subsequently purified. The definition in Regulation (EU) No 231/2012 is "Natural mica consisting mainly of potassium aluminium silicate (muscovite)" where mica refers to potassium aluminium silicate. Typically, potassium aluminium silicate contains 20% aluminium.

It appears in the form of a white crystalline powder.

What it is used for and where

Food

Ingredient listed in the European food additives list as E555 as anti-caking agent, binder and emulsifier.

Safety

The Panel on Food Additives and Flavourings (FAF) provided a scientific opinion reviewing the safety of sodium aluminium silicate (E554) and potassium aluminium silicate (E555) as food additives. Exposure to aluminium from this single use at the maximum permitted level could theoretically far exceed the tolerable weekly intake. Considering the availability of very limited toxicological data and insufficient information on the physicochemical characterisation of both food additives, the Panel concluded that it was not possible to assess the safety of sodium aluminium silicate (E554) and potassium aluminium silicate (E555). (1)

It should be considered that the risk of cumulative intake of aluminium, which can pose a danger to human health, cannot be excluded as this ingredient can be found in widely consumed food products (2).

Other uses

• animal feed
• catalyst for biodiesel production

• Molecular Formula   Al₂K₂O₆Si   KAl₂[AlSi₃O₁₀](OH)₂     
• Molecular Weight   398.31  
• CAS  12001-26-2
• UNII  058TS43PSM
• EC Number  310-127-6

References_____________________________________________________________________

(1) EFSA Panel on Food Additives and Flavourings (FAF), Younes, M., Aquilina, G., Castle, L., Engel, K.H., Fowler, P., Frutos Fernandez, M.J., Fürst, P., Gürtler, R., Gundert‐Remy, U. and Husøy, T., 2020. Re‐evaluation of sodium aluminium silicate (E 554) and potassium aluminium silicate (E 555) as food additives. EFSA Journal, 18(6), p.e06152.

(2) Wong, W.W., Chung, S.W., Kwong, K.P., Yin Ho, Y. and Xiao, Y., 2010. Dietary exposure to aluminium of the Hong Kong population. Food Additives and Contaminants, 27(4), pp.457-463.

Bratakos, S.M., Lazou, A.E., Bratakos, M.S. and Lazos, E.S., 2012. Aluminium in food and daily dietary intake estimate in Greece. Food Additives and Contaminants: Part B, 5(1), pp.33-44.