Iron Sulphite Agar, Granulated is used for detection of thermophilic anaerobic organisms causing sulphide spoilage in food. This medium can be used for detection of thermophilic anaerobic organisms causing sulphide spoilage in foods. It was shown by Beerens that 0.1% sulphite concentration in the original formula was inhibitory to some strains of Clostridium sporogenes.