One or more meat products are positioned in a meat chilling enclosure in which cooled air is added to cool the contents of the enclosure. A water spray including a desired carbon monoxide content in solution is introduced into the meat chilling enclosure. The desired carbon monoxide content may comprise no more than approximately the maximum carbon monoxide content that is held in solution in the spray water at approximately the temperature at which the spray water is introduced into the meat chilling enclosure. Alternatively, carbon monoxide held in solution in the spray water may be limited to approximately the maximum carbon monoxide content that is held in solution in the spray water at a maximum temperature maintained in the meat chilling enclosure. A pH increasing material such as ammonia gas or ammonium hydroxide solution may also be added to the meat chilling enclosure to produce and maintain a desired ammonia gas content in the enclosure atmosphere.