a method and apparatus for killing microorganisms on the surface of raw meat . the microorganisms are killed by exposing the meat to controlled applications of a biocidal treatment gas in a vacuum / pressure regulated environment . the meat is first exposed to a vacuum , the surface then flushed with an air - free treatment gas , then full treated with the air - free treatment gas , and then reexposed to a vacuum . the method and apparatus successfully kills microorganisms on the surface and pores of raw meat without causing significant deleterious changes to the meat .