Abstract: The invention relates to precipitated silica microbeads having sensory properties in the mouth, and a specific surface CTAB of at least 100 m2/g, an oil uptake of at least 200 ml/g, a mean particle diameter from 50 &mgr;m to 600 &mgr;m, at the surface from 0.5 to 2 parts by weight, (expressed as zinc metal) of a zinc derivative with a degree of oxidation of 2 per 100 parts by weight of silica, a pH from about 7 to 9, and possibly between 0.2 and 5 parts by weight of a white pigment for 100 parts by weight of silica The invention also relates to a method for producing said microbeads by precipitation, treatment of the silica slurry with a soluble zinc compound, mechanical thinning of the cake resulting from the separation of the treated silica slurry, and drying by atomization. The invention further relates to their use in toothpaste preparations as sensory agents acting in the mouth.

Abstract: The invention discloses a method for preparing particles comprising a dense silica shell and a core of another material, through rapid precipitation of active silica from a an aqueous alkaline metal silicate solution with pH adjustment by means of an acidifying agent, on a material support other than silica, separation of the silica slurry formed and drying of the recovered silica suspension. These composite particles consisting of a shell formed of dense silica and a non-polymer organic material core with biological, in particular phytosanitary, activity can be used for the slow release of the said solid non-polymer organic material with biological, in particular phytosanitary, activity, by slow diffusion through the silica shell.