Abstract: A two step antimicrobial treatment of animal carcasses prior to chill storage in a commercial slaughter operation. As a first step, the carcass is isolated in a hot water pasteurization chamber and sprayed with recirculation water at a minimum temperature of at least 165.degree. F. (74.degree. C.) over its entire surface for a minimum time sufficient to kill bacteria. Isolation is achieved with air curtains across the entrance and exit openings, an exhaust system and a liquid level control in the bottom of the chamber. Recirculation water collected in the bottom of the chamber is filtered, combined with makeup water, heated and recirculated to the chamber. As a second step, the carcass is isolated in an acid application chamber and sprayed with an organic acid solution immediately prior to delivery to the chill storage.