The present invention relates to a process for treatment of a human or animal food comprising using a ground plant material containing amorphous silica as an anti-caking agent at a usage level the same as the usage level of synthetic amorphous silica or higher and to a process comprising using a ground rice hulls containing about 15 to 23% by weight amorphous silica as an anti-caking agent in a human or animal food at a usage level the same as the usage level of synthetic amorphous silicas or higher.