A method for producing various grades of beef is disclosed. The method includes, in two or more trains, creating a mixture of fat particles, lean particles, and a fluid, wherein each train is supplied with beef of varying fat content, for each train producing separate first and second fluid streams, wherein the first fluid stream comprises lean particles, and the second fluid stream comprises fat particles, for each train, adjusting the fat content of the lean stream by adding a controlled portion from the fat stream, separately treating the lean stream from the fat stream to deactivate pathogens, and producing two or more different grades of lean beef product.
