Information required on:
Raw materials used and methods of manufacture for different
forms of silicon dioxide (pyrogenic silica, precipitated silica,
hydrated silica, silica aerogel and colloidal silica)
Identification methods allowing the differentiation between the
above forms of silicon dioxide
Functional uses of different forms, and information on the types
of products in which it is used and the use levels in these
products
Data on solubility using the procedure documented in “Compendium
of Food Additives Specifications, Vol.4, Analytical methods”
Data on the impurities soluble in 0.5 M hydrochloric acid for all
forms of silicon dioxide used as food additives, from a minimum
of five batches. If a different extraction and determination method
is used, provide data along with details of method and QC data.
Suitability of the analytical method for the determination of
aluminium, silicon and sodium using the proposed “Method of
assay” along with data, from a minimum of five batches. If a
different method is used, provide data along with details of the
method and QC data.
In addition to the above information, data on pH, loss on drying
and loss on ignition for hydrated silica, silica aerogel and
colloidal silica
SYNONYMS Silica; INS No. 551
DEFINITION Silicon dioxide is an amorphous substance, which is produced
synthetically by either a vapour-phase hydrolysis process, yielding
pyrogenic (fumed) silica, or by a wet process, yielding precipitated silica
(silica gel). Pyrogenic silica is produced in an anhydrous state, whereas
the wet process products are obtained as hydrates or contain surface
absorbed water.