Disinfectants should be effective and rapidly acting in killing microorganisms (Fig. 494). It should be noted that disinfectants do not sterilize the surfaces treated, absolute germ-free surfaces cannot be achieved, but disinfectants should kill all pathogens. The chemical composition of disinfectants vary depending on the specific target (slaughterhouse, meat processing, easily accessible open processing lines or closed food pipeline systems) and on chemical formulations by the individual disinfectant manufacturer. Modern disinfectants are mostly mixtures of different chemical substances. Combinations of disinfection chemicals achieve a synergistic effect and result in the elimination of a broader spectrum of microorganisms. The exact compositions are sometimes not fully revealed by the manufacturers. In principle the following groups of substances are used